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How to Create and Set Up a Telegram Chatbot

How to Create and Set Up a Telegram Chatbot
Hostman Team
Technical writer
Python
12.03.2025
Reading time: 18 min

Chatbots are software programs that simulate communication with users. Today, we use them for a wide range of purposes, from simple directories to complex services integrated with CRM systems and payment platforms.

People create bots for Telegram, Viber, Facebook Messenger, and other messaging platforms. Each platform has its own rules and capabilities—some lack payment integration, while others don't support flexible keyboards. This article focuses on user-friendly Telegram, which has a simple API and an active audience.

In this article, we will cover:

  • How to create a Telegram bot on your own
  • When it's convenient to use chatbot builders for development
  • How to integrate a chatbot with external services and APIs
  • What is needed for the bot to function smoothly
  • The key features of Aiogram, a popular Python library for chatbot development

And if you’re looking for a reliable, high-performance, and budget-friendly solution for your workflows, Hostman has you covered with Linux VPS Hosting options, including Debian VPS, Ubuntu VPS, and VPS CentOS.

Creating a Telegram Chatbot Without Programming Skills

Chatbot builders are becoming increasingly popular. These services allow you to create a bot using a simple "drag-and-drop" interface. No programming knowledge is required—you just build logic blocks like in a children's game.

However, there are some drawbacks to using chatbot builders:

  • Limited functionality. Most chatbot builders provide only a portion of Telegram API's capabilities. For example, not all of them allow integration with third-party services via HTTP requests. Those that do often have expensive pricing plans.
  • Generic scenarios. The minimal flexibility of builders leads to chatbots that look and function similarly.
  • Dependence on the service. If the platform goes offline or its pricing increases, you may have to migrate your bot elsewhere.

Builders are useful for prototyping and simple use cases—such as a welcome message, answering a few questions, or collecting contact information. However, more complex algorithms require knowledge of variables, data processing logic, and the Telegram API. Even when using a builder, you still need to understand how to address users by name, how inline keyboards work, and how to handle bot states.

Free versions of chatbot builders often come with limitations:

  • They may include advertising messages.
  • Some prevent integration with essential APIs.
  • Others impose limits on the number of users.

These restrictions can reduce audience engagement, making the chatbot ineffective. In the long run, premium versions of these builders can end up costing more than developing a bot from scratch and hosting it on your own server.

If you need a chatbot to handle real business tasks, automate processes, or work with databases, builders are often not sufficient. In such cases, hiring a developer is a better solution. A developer can design a flexible architecture, choose optimal technologies, and eliminate technical constraints that might hinder the project's scalability. If you already have a prototype built with a chatbot builder, you can use its logic as a starting point for technical specifications.

How to Create a Telegram Chatbot

Now, let's discuss how to create a Telegram chatbot using Python. You’ll need basic knowledge of variables, conditional statements, loops, and functions in Python.

To create chatbots, you can use a framework which is a set of tools, libraries, and ready-made solutions that simplify software development. You can work with the raw Telegram API and implement functionality using HTTP requests, but even for simple tasks, this approach requires writing thousands of lines of code.

In this guide, we’ll use Aiogram, one of the most popular frameworks for building Telegram chatbots in Python.

Step 1: Create a Virtual Environment for Your Project

Using a virtual environment in any Python project is considered good practice. Additionally, chatbots are often deployed on cloud servers where dependencies need to be installed. A virtual environment makes it easy to export a list of dependencies specific to your project.

Install the Python virtual environment:

sudo apt install python3-venv -y

Create a virtual Python environment in the working directory:

python -m venv venv

Activate the environment:

source ./venv/bin/activate

Step 2: Install Required Libraries

Install the Aiogram framework using pip:

pip install aiogram

Add a library for working with environment variables. We recommend this method for handling tokens in any project, even if you don’t plan to make it public. This reduces the risk of accidentally exposing confidential data.

pip install python-dotenv

You can also install any other dependencies as needed.

Step 3: Initialize Your Chatbot via BotFather

This is a simple step, but it often causes confusion. We need to interact with a Telegram bot that will generate and provide us with a token for our project.

  1. Open Telegram and start a chat with @BotFather.
  2. Click the Start button.
  3. The bot will send a welcome message. Enter the following command:
/newbot
  1. BotFather will ask for a name for your bot—this is what users will see in their chat list.
  2. Then, enter a username for your bot. It must be unique and end with "bot" (e.g., mycoolbot).
  3. Once completed, BotFather will create your chatbot, assign it a username, and provide you with a token.

Keep your token secret. Anyone with access to it can send messages on behalf of your chatbot. If your token is compromised, immediately generate a new one via BotFather.

Next, open a chat with your newly created bot and configure the following:

  1. Click the Edit button.
  2. Update the profile picture.
  3. Set a welcome message.
  4. Add a description.
  5. Configure default commands.

Step 4: Store Your Token Securely

Create an environment file named .env (this file has no name, only an extension). Add the following line:

BOT_TOKEN = your_generated_token

On Linux and macOS, you can quickly save the token using the following command:

echo "BOT_TOKEN = your_generated_token" > .env

Step 4: Create the Script

In your working directory, create a file called main.py—this will be the main script for your chatbot.

Now, import the following test code, which will send a welcome message to the user when they enter the /start command:

import asyncio  # Library for handling asynchronous code
import os  # Module for working with environment variables
from dotenv import load_dotenv  # Function to load environment variables from the .env file
from aiogram import Bot, Dispatcher, Router  # Import necessary classes from aiogram
from aiogram.types import Message  # Import Message class for handling incoming messages
from aiogram.filters import CommandStart  # Import filter for handling the /start command
 
# Create a router to store message handlers
router = Router()
 
# Load environment variables from .env
load_dotenv()
 
# Handler for the /start command
@router.message(CommandStart())  # Filter to check if the message is the /start command
async def cmd_start(message: Message) -> None:
    # Retrieve the user's first name and last name (if available)
    first_name = message.from_user.first_name
    last_name = message.from_user.last_name or ""  # If no last name, use an empty string
 
    # Send a welcome message to the user
    await message.answer(f"Hello, {first_name} {last_name}!")
 
# Main asynchronous function to start the bot
async def main():
    # Create a bot instance using the token from environment variables
    bot = Bot(token=os.getenv("BOT_TOKEN"))
 
    # Create a dispatcher to handle messages
    dp = Dispatcher()
 
    # Include the router with command handlers
    dp.include_router(router)
 
    # Start the bot in polling mode
    await dp.start_polling(bot)
 
# If the script is run directly (not imported as a module),
# execute the main() function
if __name__ == "__main__":
    asyncio.run(main())

The script is well-commented to help you understand the essential parts.If you don't want to dive deep, you can simply use Dispatcher and Router as standard components in Aiogram. We will explore their functionality later in this guide.

This ready-made structure can serve as a solid starting point for any chatbot project. As you continue development, you will add more handlers, keyboards, and states.

Step 5: Run and Test the Chatbot

Now, launch your script using the following command:

python main.py

Now you can open a chat with your bot in Telegram and start interacting with it.

Aiogram Framework v3.x Features Overview 

You only need to understand a few key components and functions of Aiogram to create a Telegram chatbot.

This section covers Aiogram v3.x, which was released on September 1, 2023. Any version starting with 3.x will work. While older projects using Aiogram 2.x still exist, version 2.x is now considered outdated.

Key Components of Aiogram

Bot

The Bot class serves as the interface to the Telegram API. It allows you to send messages, images, and other data to users.

bot = Bot(token=os.getenv("TOKEN"))

You can pass the token directly when initializing the Bot class, but it's recommended to use environment variables to prevent accidental exposure of your bot token.

Dispatcher

The Dispatcher is the core of the framework. It receives updates (incoming messages and events) and routes them to the appropriate handlers.

dp = Dispatcher()

In Aiogram v3, a new structure with Router is used (see below), but the Dispatcher is still required for initialization and launching the bot.

Router

In Aiogram v3, handlers are grouped within a Router. This is a separate entity that stores the bot's logic—command handlers, message handlers, callback handlers, and more.

from aiogram import Router
router = Router()

After defining handlers inside the router, developers register it with the Dispatcher:

dp.include_router(router)

Handling Commands

The most common scenario is responding to commands like /start or /help.

from aiogram import F
from aiogram.types import Message

@router.message(F.text == "/start")
async def cmd_start(message: Message):
    await message.answer("Hello! I'm a bot running on Aiogram.")
  • F.text == "/start" is a new filtering method in Aiogram v3.
  • message.answer(...) sends a reply to the user.

Handling Regular Messages

To react to any message, simply remove the filter or define a different condition:

@router.message()
async def echo_all(message: Message):
    await message.answer(f"You wrote: {message.text}")

In this example, the bot echoes whatever text the user sends.

Inline Buttons and Keyboards

from aiogram.types import InlineKeyboardButton, InlineKeyboardMarkup

inline_kb = InlineKeyboardMarkup(
    inline_keyboard=[
        [InlineKeyboardButton(text="Click me!", callback_data="press_button")]
    ]
)

@router.message(F.text == "/buttons")
async def show_buttons(message: Message):
    await message.answer("Here are my buttons:", reply_markup=inline_kb)

When the user clicks the button, the bot receives callback_data="press_button", which can be handled separately:

from aiogram.types import CallbackQuery

@router.callback_query(F.data == "press_button")
async def handle_press_button(callback: CallbackQuery):
    await callback.message.answer("You clicked the button!")
    await callback.answer()  # Removes the "loading" animation in the chat

Regular Buttons (Reply Keyboard)

Regular buttons differ from inline buttons in that they replace the keyboard. The user immediately sees a list of available response options. These buttons are tracked by the message text, not callback_data.

from aiogram.types import ReplyKeyboardMarkup, KeyboardButton, ReplyKeyboardRemove

# Creating a reply keyboard
reply_kb = ReplyKeyboardMarkup(
    keyboard=[
        [
            KeyboardButton(text="View Menu"),
            KeyboardButton(text="Place Order")
        ]
    ],
    resize_keyboard=True  # Automatically adjusts button size
)

# Handling the /start command and showing the reply keyboard
@router.message(F.text == "/start")
async def start_cmd(message: Message):
    await message.answer(
        "Welcome! Choose an action:",
        reply_markup=reply_kb
    )

# Handling "View Menu" button press
@router.message(F.text == "View Menu")
async def show_menu(message: Message):
    await message.answer("We have pizza and drinks.")

# Handling "Place Order" button press
@router.message(F.text == "Place Order")
async def make_order(message: Message):
    await message.answer("What would you like to order?")

# Command to hide the keyboard
@router.message(F.text == "/hide")
async def hide_keyboard(message: Message):
    await message.answer("Hiding the keyboard", reply_markup=ReplyKeyboardRemove())

Filters and Middlewares

Filters

Filters help define which messages should be processed. You can also create custom filters.

from aiogram.filters import Filter

# Custom filter to check if a user is an admin
class IsAdmin(Filter):
    def __init__(self, admin_id: int):
        self.admin_id = admin_id

    async def __call__(self, message: Message) -> bool:
        return message.from_user.id == self.admin_id

# Using the filter to restrict a command to the admin
@router.message(IsAdmin(admin_id=12345678), F.text == "/admin")
async def admin_cmd(message: Message):
    await message.answer("Hello, Admin! You have special privileges.")

Middlewares

Middlewares act as intermediary layers between an incoming request and its handler. You can use them to intercept, modify, validate, or log messages before they reach their respective handlers.

import logging
from aiogram.types import CallbackQuery, Message
from aiogram.dispatcher.middlewares.base import BaseMiddleware

# Custom middleware to log incoming messages and callbacks
class LoggingMiddleware(BaseMiddleware):
    async def __call__(self, handler, event, data):
        if isinstance(event, Message):
            logging.info(f"[Message] from {event.from_user.id}: {event.text}")
        elif isinstance(event, CallbackQuery):
            logging.info(f"[CallbackQuery] from {event.from_user.id}: {event.data}")

        # Pass the event to the next handler
        return await handler(event, data)

async def main():
    load_dotenv()
    logging.basicConfig(level=logging.INFO)

    bot = Bot(token=os.getenv("BOT_TOKEN"))
    dp = Dispatcher()

    # Attaching the middleware
    dp.update.middleware(LoggingMiddleware())

    dp.include_router(router)
    await dp.start_polling(bot)

Working with States (FSM) in Aiogram 3

Aiogram 3 supports Finite State Machine (FSM), which is useful for step-by-step data collection (e.g., user registration, order processing). FSM is crucial for implementing multi-step workflows where users must complete one step before moving to the next.

For example, in a pizza ordering bot, we need to ask the user for pizza size and delivery address, ensuring the process is sequential. We must save each step's data until the order is complete.

Step 1: Declare States

from aiogram.fsm.state import State, StatesGroup

class OrderPizza(StatesGroup):
    waiting_for_size = State()
    waiting_for_address = State()

These states define different stages in the ordering process.

Step 2: Switch between states

from aiogram.fsm.context import FSMContext

@router.message(F.text == "/order")
async def cmd_order(message: Message, state: FSMContext):
    # Create inline buttons for selecting pizza size
    size_keyboard = InlineKeyboardMarkup(
        inline_keyboard=[
            [
                InlineKeyboardButton(text="Large", callback_data="size_big"),
                InlineKeyboardButton(text="Medium", callback_data="size_medium"),
                InlineKeyboardButton(text="Small", callback_data="size_small")
            ]
        ]
    )

    await message.answer(
        "What size pizza would you like? Click one of the buttons:",
        reply_markup=size_keyboard
    )
    # Set the state to wait for the user to choose a size
    await state.set_state(OrderPizza.waiting_for_size)

# Step 2: Handle button click for size selection
@router.callback_query(OrderPizza.waiting_for_size, F.data.startswith("size_"))
async def choose_size_callback(callback: CallbackQuery, state: FSMContext):
    # Callback data can be size_big / size_medium / size_small
    size_data = callback.data.split("_")[1]  # e.g., "big", "medium", or "small"

    # Save the selected pizza size in the temporary state storage
    await state.update_data(pizza_size=size_data)

    # Confirm the button press (removes "loading clock" in Telegram's UI)
    await callback.answer()

    await callback.message.answer("Please enter your delivery address:")
    await state.set_state(OrderPizza.waiting_for_address)

# Step 2a: If the user sends a message instead of clicking a button (in waiting_for_size state),
# we can handle it separately. For example, prompt them to use the buttons.
@router.message(OrderPizza.waiting_for_size)
async def handle_text_during_waiting_for_size(message: Message, state: FSMContext):
    await message.answer(
        "Please select a pizza size using the buttons above. "
        "We cannot proceed without this information."
    )

# Step 3: User sends the delivery address
@router.message(OrderPizza.waiting_for_address)
async def set_address(message: Message, state: FSMContext):
    address = message.text
    user_data = await state.get_data()
    pizza_size = user_data["pizza_size"]

    size_text = {
        "big": "large",
        "medium": "medium",
        "small": "small"
    }.get(pizza_size, "undefined")

    await message.answer(f"You have ordered a {size_text} pizza to be delivered at: {address}")
    # Clear the state — the process is complete
    await state.clear()

Notice how the temporary storage keeps track of user responses at each step. This storage is user-specific and does not require a database.

The user progresses through a chain of questions, and at the end, the order details can be sent to an internal API. 

Deploying the Bot: Running on a Server

Let's go through two main deployment methods.

Quick Method: Docker + Hostman App Platform

This method does not require any system administration knowledge; the entire deployment process is automated. Additionally, it helps save costs. Follow these steps:

  1. Export all project dependencies to a requirements.txt file. Using a virtual environment is recommended to avoid pulling in libraries from the entire system. Run the following command in the project directory terminal:

pip freeze > requirements.txt
  1. Add a deployment file to the project directory — Dockerfile. This file has no extension, just the name. Insert the following content:

FROM python:3.11
WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
EXPOSE 9999
CMD ["python", "main.py"]
  1. Create a Git repository and push it to GitHub. You can use a minimal set of Git commands from our guide by running these commands in sequence. Add the environment variables file (.env) to .gitignore to prevent it from being exposed publicly.
  2. Go to the Hostman control panel, select the App platform section, and click Create app. Go to the Docker tab and select Dockerfile.

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  1. Link your GitHub account or connect your Git repository via URL.
  2. Select the repository from the list after linking your GitHub account.
  3. Choose a configuration. Hostman Apps offers a configuration of 1 CPU x 3.3GHz, 1GB RAM, NVMe storage, which is ideal for simple text-based bots, projects with small inline keyboards, basic FSM logic, low-demand API requests, working with SQLite, or lightweight JSON files. This configuration can handle 50-100 users per minute.
  4. Add the bot token to environment variables. In the App settings, click + Add, enter BOT_TOKEN as the key, and paste the token obtained from BotFather as the value.
  5. Start the deployment and wait for it to complete. Once finished, the bot will be up and running.

Standard Method: Ubuntu + systemd

  1. Export all project dependencies to the requirements.txt file. Run the following command in the Terminal while in the project directory:

pip freeze > requirements.txt
  1. Create a cloud server in the Hostman panel with the desired configuration and Ubuntu OS.

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  1. Transfer project files to the directory on the remote server. The easiest way to do this is using the rsync utility if you're using Ubuntu/MacOS:

rsync -av --exclude="venv" --exclude=".idea" --exclude=".git" ./ root@176.53.160.13:/root/project

Don’t forget to replace the server IP and correct the destination directory. 

Windows users can use FileZilla to transfer files. 

  1. Connect to the server via SSH.

  2. Install the package for virtual environments:

sudo apt install python3.10-venv
  1. Navigate to the project directory where you transferred the files. Create a virtual environment and install the dependencies:

python -m venv venv
source venv/bin/activate
pip install -r requirements.txt
  1. Test the bot functionality by running it:

python main.py

If everything works, proceed to the next step.

  1. Create the unit file /etc/systemd/system/telegram-bot.service:

sudo nano /etc/systemd/system/telegram-bot.service
  1. Add the following content to the file:

[Unit]
Description=Telegram Bot Service
After=network.target

[Service]
User=root
WorkingDirectory=/root/project
ExecStart=/root/proj/venv/bin/python /root/proj/main.py
Restart=always
RestartSec=5
[Install]
WantedBy=multi-user.target
  • WorkingDirectory — the project directory
  • ExecStart — the command to start the chatbot in the format <interpreter> <full path to the file>.

If using a virtual environment, the path to the interpreter will be as in the example. If working without venv, use /usr/local/bin/python3.

  1. Reload systemd and enable the service:

sudo systemctl daemon-reload
sudo systemctl enable telegram-bot.service
sudo systemctl start telegram-bot.service
  1. Check the status of the service and view logs if necessary:

sudo systemctl status telegram-bot.service

If the bot is running correctly, the Active field should show active (running).

View bot logs:

sudo journalctl -u telegram-bot.service -f

Manage the service with the following commands:

Restart the bot:

sudo systemctl restart telegram-bot.service

Stop the bot:

sudo systemctl stop telegram-bot.service

Remove the service (if needed):

sudo systemctl disable telegram-bot.service
sudo rm /etc/systemd/system/telegram-bot.service
sudo systemctl daemon-reload

Conclusion

Creating a Telegram chatbot in Python is a task that can be accomplished even without programming experience using bot builders. However, if you need flexibility and more options, it's better to master the aiogram framework and deploy your own project. This gives you full control over the code, the ability to enhance functionality, manage integrations, and avoid the limitations of paid plans.

To run the bot in production, simply choose an appropriate configuration on the Hostman App Platform and set up automatic deployment. Pay attention to security by storing the token in an environment variable and encrypting sensitive data. In the future, you can scale the bot, add webhook support, integrate payment systems and analytics systems, and work with ML models if AI features are required.

Python
12.03.2025
Reading time: 18 min

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At the beginning of the command, specify the required Python version in the variable PYVER and then execute the command: export PYVER=3.9 && sudo apt update && sudo apt upgrade -y && sudo apt install -y software-properties-common && sudo add-apt-repository ppa:deadsnakes/ppa -y && sudo apt update && sudo apt install -y python${PYVER} python${PYVER}-venv python${PYVER}-dev python3-pip && python${PYVER} -m venv venv && source venv/bin/activate && pip install --upgrade pip && [ -f requirements.txt ] && pip install -r requirements.txt Tip 5. Include Error Handlers in Your Algorithm When developing a parser, it is important to provide an error handling mechanism. Network failures, changes in the HTML structure, or unexpected blocking by the site may lead to script failures. Add retries for requests, timeouts, and a logging system for all actions and errors. This approach allows you to quickly detect problems, adjust parsing algorithms, and ensure the stability of the application even when the donor site changes. In Python, you can use: try, except, finally constructs; the logging library for logging; loops for retrying failed requests; timeouts, for example: requests: requests.get("hostman.com", timeout=20) aiohttp: timeout = aiohttp.ClientTimeout(total=60, sock_connect=10, sock_read=10)  async with aiohttp.ClientSession(timeout=timeout) as session:      async with session.get(url) as response:          return await response.text() Tip 6. Implement Your Parser as a Generator A generator is a class that implements the logic of an object that iteratively yields elements as needed. Generators are especially convenient to use when developing a parsing script for the following reasons: Lazy evaluation. Generators calculate and return data “on the fly,” which makes it possible to process large volumes of information without consuming significant amounts of memory. When parsing large files or web pages, this is critical: data is processed gradually, and only the current part is stored in memory, not the entire result at once. Increased performance. Since elements are generated as needed, you can begin processing and transferring data (for example, to a database or a bot) before the entire dataset has been obtained. This reduces delays and allows you to react faster to incoming data. Code organization convenience. Generators simplify the implementation of iterative processes, allowing you to focus on the parsing logic rather than managing iteration state. This is especially useful when you need to process a data stream and pass it to other parts of the system. Example of Implementing a Parser as a Generator in Python In the loop where the generator is used, it is convenient to initiate writing data to a database or, for example, sending notifications through a Telegram bot. Using generators makes the code more readable. import requests from bs4 import BeautifulSoup class MyParser: def __init__(self, url): self.url = url def parse(self): """ Generator that sequentially returns data (for example, titles of elements on a page). """ response = requests.get(self.url) if response.status_code != 200: raise Exception(f"Failed to retrieve page, status: {response.status_code}") soup = BeautifulSoup(response.text, "html.parser") items = soup.select("div") for item in items: title = item.select_one("h1").get_text(strip=True) if item.select_one("h1") else "No title" yield { "title": title, "content": item.get_text(strip=True) } if __name__ == "__main__": parser = MyParser("https://example.com") for data_item in parser.parse(): print(data_item["title"], "--", data_item["content"]) Tip 7. Use an Asynchronous Approach to Speed Up Processing a Large Number of Requests When parsing a large number of pages, a synchronous approach often becomes a bottleneck, since each request waits for the previous one to finish. Asynchronous libraries, such as aiohttp in Python, allow you to execute many requests simultaneously, which significantly speeds up data collection. However, to avoid overloading both your application and the donor servers, it is important to properly regulate the request flow. This is where throttling, exponential backoff, and task queue techniques come into play. How It Works Asynchronous requests. Create an asynchronous session with specified timeouts (for example, total timeout, connection timeout, and read timeout). This allows you to process many requests in parallel without blocking the main execution thread. Throttling. To prevent excessive load on the donor server, it makes sense to limit the number of simultaneous requests. This can be done using semaphores or other concurrency control mechanisms (for example, asyncio.Semaphore), so as not to send requests faster than allowed. Exponential backoff. If a request fails (for example, due to a timeout or temporary blocking), use an exponential backoff strategy. On each retry, the waiting interval increases (for example, 1 second, then 2, 4, 8…), which allows the server to recover and reduces the likelihood of repeated errors. Task queues. Organizing queues (for example, with asyncio.Queue) helps manage a large flow of requests. First, a queue of URLs is formed, then requests are processed as “slots” become available for execution. This ensures an even distribution of load and stable operation of the parser. Example of Implementation in Python Using aiohttp import asyncio import aiohttp from aiohttp import ClientTimeout # Limit the number of simultaneous requests semaphore = asyncio.Semaphore(10) async def fetch(session, url): async with semaphore: try: async with session.get(url) as response: return await response.text() except Exception: # Apply exponential backoff in case of error for delay in [1, 2, 4, 8]: await asyncio.sleep(delay) try: async with session.get(url) as response: return await response.text() except Exception: continue return None async def main(urls): timeout = ClientTimeout(total=60, sock_connect=10, sock_read=10) async with aiohttp.ClientSession(timeout=timeout) as session: tasks = [asyncio.create_task(fetch(session, url)) for url in urls] results = await asyncio.gather(*tasks) # Process the obtained data for result in results: if result: print(result[:200]) # Print the first 200 characters of the response # Example list of URLs for parsing urls = ["http://hostman.com"] * 100 asyncio.run(main(urls)) Recommendations for Developers There are also recommendations that will help simplify a developer’s work: Check if the donor site has a public API. Sometimes the task of writing a parsing algorithm has already been solved, and the site offers a convenient API that fully covers the required functionality. Monitor changes in the site’s structure. Donor site developers may change the layout, which would require you to update the selectors of the elements used in your code. Test function execution at every stage. Automated tests (unit tests, integration tests) help promptly detect issues related to site structure changes or internal code modifications. Checklist for Determining the Parsing Method We have systematized the information from this article so you can understand which parsing method to use when working with any donor site. Conclusion The universal parsing methods presented here form a reliable foundation for developing algorithms capable of extracting data from a wide variety of websites, regardless of the programming language chosen. Following these scraping best practices and tips allows you to build a flexible, scalable, and change-resistant algorithm. Such an approach not only helps to optimally use system resources but also ensures the ability to quickly integrate the obtained data with databases, messengers, or other external services.
23 September 2025 · 12 min to read
Python

How to Use Python time.sleep()

Sometimes, while running a program, it’s necessary to pause: wait for data to load, give the user time to enter input, or reduce the load on the system. One of the simplest ways to achieve this in Python is with the time.sleep() function, which suspends program execution for a given interval. In this article, we’ll examine how time.sleep() works in Python, its features and alternatives, as well as possible errors. We’ll discuss when it’s appropriate to use it in multithreaded and asynchronous programs, and when it’s better to choose asyncio.sleep() or other waiting mechanisms. What is the sleep() Function in Python? Python's time.sleep() function can be used to freeze the current thread's execution for a specific period of time. The built-in time module in Python contains this function. This function in Python was added to the standard library to simplify creating pauses in code. It is located in the time module and is called time.sleep, allowing you to pause program execution for a specified number of seconds. In practice, sleep() is useful for pauses in test environments, delays between API requests, or intervals between sending messages. However, you should not confuse its use for system-level tasks, such as thread synchronization, with simply slowing down a script. If precise timing coordination or asynchronous I/O is needed, other tools are more suitable. How time.sleep() Works The time.sleep() function in Python pauses the current thread for the specified number of seconds. In a multithreaded scenario, other threads continue running, but the one where time.sleep() was called remains "frozen" for that interval. It’s important to note that time.sleep() blocks code execution at that point, delaying all subsequent operations. Ignoring this rule can lead to reduced performance or even a frozen user interface in desktop applications. When time.sleep() is Used Most often, time.sleep() is used in testing and debugging, when a short delay is needed—for example, to verify the correctness of an API response or wait for a server reply. It’s also used for step-by-step script execution, giving the user time to view information or enter data. In demonstrations, tutorials, and prototyping, time.sleep() helps simulate long-running processes, and when working with external services, it helps avoid penalties or blocks from too frequent requests. However, sleep() is not the only way to slow down code execution. Further in the article, we’ll review some alternatives. How to Use time.sleep() in Python You must import the time module before you can use time.sleep(). The required delay in seconds can then be passed as a parameter when calling time.sleep(). For a few seconds, this delay may be expressed as a floating-point number or as a whole number.  Basic Syntax of time.sleep() To call the time.sleep() function, first import the time module: import time time.sleep(5) In this example, the program will "sleep" for 5 seconds. The number passed to the function can be either an integer or a float, which allows sleeping for fractions of a second. Syntax: time.sleep(seconds) The time.sleep() function does not return any value. That means you cannot precisely determine how accurate the pause was—it simply suspends the current thread for the specified duration. Example: Delaying Code Execution Suppose you have a small script that prints messages with a 2-second interval. To add a delay in Python, just insert time.sleep(2): import time print("First message") time.sleep(2) print("Second message") time.sleep(2) print("Third message") When running this script, the user will see a 2-second pause between each message. That’s exactly how a delay in Python works using time.sleep(2). Parameters of time.sleep() The time.sleep() function accepts only one parameter, but it can be either an integer or a float. This adds flexibility when implementing delays in Python. Passing Values in Seconds Most examples of time.sleep() usage pass an integer representing seconds. For example: time.sleep(10) Here, the script pauses for 10 seconds. This is convenient when you need a long pause or want to limit request frequency. Using Fractions of a Second (Milliseconds) Sometimes you need to pause for a few milliseconds or fractions of a second. To do this, you can pass a floating-point number: time.sleep(0.5) This creates a half-second pause. However, because of OS and Python timer limitations, the delay may slightly exceed 500 milliseconds. For most tasks, this isn’t critical, but in high-precision real-time systems, specialized tools should be used instead. Alternative Ways to Pause in Python Although time.sleep() is the most popular and simplest way to create pauses, there are other methods that may be more suitable when waiting for external events or handling multiple threads. Let’s look at the most common alternatives. Using input() for Waiting The simplest way to pause in Python is by calling input(). It suspends execution until the user presses Enter or enters data. Example: print("Press Enter to continue...") input() print("Resuming program execution") While this feels like a pause, technically it’s not a timed delay. The program waits for user action, not a fixed interval. This method is rarely useful in automated scripts but can be handy in debugging or console utilities where a "pause on demand" is needed. Waiting with threading.Event() If you’re writing a multithreaded program, it can be more useful to use synchronization objects like threading.Event(). You can configure it to block a thread until a signal is received. Example: import threading event = threading.Event() def worker():     print("Starting work in thread")     event.wait()     print("Event received, resuming work") thread = threading.Thread(target=worker) thread.start() import time time.sleep(3) event.set() In this case, the thread is blocked until event.set() is called. You can still use time.sleep() to set a maximum pause, but unlike plain sleep(), this approach allows more flexible control. The thread can be "woken up" immediately without waiting for the full interval. asyncio.sleep() for Asynchronous Programs In asynchronous Python programming (asyncio module), asyncio.sleep() is used. Unlike time.sleep(), it doesn’t block the entire thread but only suspends the current coroutine, allowing the event loop to continue running other tasks. Example: import asyncio async def main(): print("Start async work") await asyncio.sleep(2) print("2 seconds passed, resuming") asyncio.run(main()) This is especially useful when you have multiple asynchronous functions that should run in parallel without interfering with each other. If you use regular time.sleep() in async code, it will block the entire event loop, causing other coroutines to wait too. Common Issues When Using time.sleep()  The time.sleep() function is simple, but misusing it can cause unexpected problems. It’s important to understand how it affects program execution so you don’t block important processes. Blocking the Main Thread The main feature of time.sleep() is that it blocks the thread where it was called. If you use it in the main thread of a GUI application (for example, Tkinter or PyQt), the interface will stop responding, creating a "frozen" effect. To avoid this, use time.sleep() only in separate threads or switch to asynchronous approaches like asyncio.sleep() for non-blocking delays. In GUI applications, it’s better to use timers (QTimer, after, etc.), which call functions at intervals without blocking the interface. Use in Multithreaded and Asynchronous Code In multithreaded code, time.sleep() can be called independently in each thread, but note that it doesn’t automatically release the Global Interpreter Lock (GIL). While other threads can still run during one thread’s sleep, in Python this depends on OS-level thread scheduling. In asynchronous code, time.sleep() should be used cautiously. If called inside an event loop (like with asyncio.run()), it blocks the entire loop, defeating the benefits of async programming. Instead, use asyncio.sleep(), which hands control back to the scheduler, letting other coroutines run in the background. Real-World Example of Using time.sleep() Imagine you’re writing a script to periodically poll an external API, which, according to its rules, must not be called more than once every 30 seconds. If requests are too frequent, the server may return errors or block your IP. Solution using time.sleep(): import time def poll_api(): print("Making API request...") def main(): while True: poll_api() time.sleep(30) if __name__ == "__main__": main() Here, after each request, we pause for 30 seconds with time.sleep(). This ensures no more than two requests per minute, respecting the limits. Async alternative: import asyncio async def poll_api(): print("Making API request...") async def main(): while True: await poll_api() await asyncio.sleep(30) if __name__ == "__main__": asyncio.run(main()) This version doesn’t block the entire program, allowing other requests or tasks to run in the same async environment. It’s more flexible and scalable. Conclusion Organizing pauses and delays is an important aspect of Python development. time.sleep() is the first and most obvious tool for this, but choosing between time.sleep(), asyncio.sleep(), and other methods should depend on your project’s architecture. In single-threaded scripts and console utilities, time.sleep() is perfectly fine, but for multithreaded and asynchronous applications, other mechanisms are better. Key recommendations: Use time.sleep() for short delays in tests, pauses between requests, or interface demonstrations. Don’t block the main thread of GUI applications to avoid a "frozen" interface. In async code, replace time.sleep() with asyncio.sleep() to keep the event loop efficient. In multithreaded programs, remember only the current thread pauses, but GIL affects scheduling. In special cases, use threading.Event() or input() to wait for events or user actions.
19 September 2025 · 8 min to read
Python

How to Delete Characters from a String in Python

When writing Python code, developers often need to modify string data. Common string modifications include: Removing specific characters from a sequence Replacing characters with others Changing letter case Joining substrings into a single sequence In this guide, we will focus on the first transformation—deleting characters from a string in Python. It’s important to note that strings in Python are immutable, meaning that any method or function that modifies a string will return a new string object with the changes applied. Methods for Deleting Characters from a String This section covers the main methods in Python used for deleting characters from a string. We will explore the following methods: replace() translate() re.sub() For each method, we will explain the syntax and provide practical examples. replace() The first Pyhton method we will discuss is replace(). It is used to replace specific characters in a string with others. Since strings are immutable, replace() returns a new string object with the modifications applied. Syntax: original_string.replace(old, new[, count]) Where: original_string – The string where modifications will take place old – The substring to be replaced new – The substring that will replace old count (optional) – The number of occurrences to replace (if omitted, all occurrences will be replaced) First, let’s remove all spaces from the string "H o s t m a n": example_str = "H o s t m a n" result_str = example_str.replace(" ", "") print(result_str) Output: Hostman We can also use the replace() method to remove newline characters (\n). example_str = "\nHostman\nVPS" print(f'Original string: {example_str}') result_str = example_str.replace("\n", " ") print(f'String after adjustments: {result_str}') Output: Original string: Hostman VPS String after adjustments: Hostman VPS The replace() method has an optional third argument, which specifies the number of replacements to perform. example_str = "Hostman VPS Hostman VPS Hostman VPS" print(f'Original string: {example_str}') result_str = example_str.replace("Hostman VPS", "", 2) print(f'String after adjustments: {result_str}') Output: Original string: Hostman VPS Hostman VPS Hostman VPS String after adjustments: Hostman VPS Here, only two occurrences of "Hostman VPS" were removed, while the third occurrence remained unchanged. We have now explored the replace() method and demonstrated its usage in different situations. Next, let’s see how we can delete and modify characters in a string using translate(). translate( The Python translate() method functions similarly to replace() but with additional flexibility. Instead of replacing characters one at a time, it allows mapping multiple characters using a dictionary or translation table. The method returns a new string object with the modifications applied. Syntax: original_string.translate(mapping_table) In the first example, let’s remove all occurrences of the $ symbol in a string and replace them with spaces: example_str = "Hostman$Cloud$—$Cloud$Service$Provider." print(f'Original string: {example_str}') result_str = example_str.translate({ord('$'): ' '}) print(f'String after adjustments: {result_str}') Output: Original string: Hostman$Cloud$—$Cloud$Service$Provider. String after adjustments: Hostman Cloud — Cloud Service Provider. To improve code readability, we can define the mapping table before calling translate(). This is useful when dealing with multiple replacements: example_str = "\nHostman%Cloud$—$Cloud$Service$Provider.\n" print(f'Original string: {example_str}') # Define translation table example_table = {ord('\n'): None, ord('$'): ' ', ord('%'): ' '} result_str = example_str.translate(example_table) print(f'String after adjustments: {result_str}') Output: Original string: Hostman%Cloud$—$Cloud$Service$Provider. String after adjustments: Hostman Cloud — Cloud Service Provider. re.sub() In addition to replace() and translate(), we can use regular expressions for more advanced character removal and replacement. Python's built-in re module provides the sub() method, which searches for a pattern in a string and replaces it. Syntax: re.sub(pattern, replacement, original_string [, count=0, flags=0]) pattern – The regular expression pattern to match replacement – The string or character that will replace the matched pattern original_string – The string where modifications will take place count (optional) – Limits the number of replacements (default is 0, meaning replace all occurrences) flags (optional) – Used to modify the behavior of the regex search Let's remove all whitespace characters (\s) using the sub() method from the re module: import re example_str = "H o s t m a n" print(f'Original string: {example_str}') result_str = re.sub('\s', '', example_str) print(f'String after adjustments: {result_str}') Output: Original string: H o s t m a nString after adjustments: Hostman Using Slices to Remove Characters In addition to using various methods to delete characters, Python also allows the use of slices. As we know, slices extract a sequence of characters from a string. To delete characters from a string by index in Python, we can use the following slice: example_str = "\nHostman \nVPS" print(f'Original string: {example_str}') result_str = example_str[1:9] + example_str[10:] print(f'String after adjustments: {result_str}') In this example, we used slices to remove newline characters. The output of the code: Original string:HostmanVPSString after adjustments: Hostman VPS Apart from using two slice parameters, you can also use a third one, which specifies the step size for index increments. For example, if we set the step to 2, it will remove every odd-indexed character in the string. Keep in mind that indexing starts at 0. Example: example_str = "Hostman Cloud" print(f'Original string: {example_str}') result_str = example_str[::2] print(f'String after adjustments: {result_str}') Output: Original string: Hostman CloudString after adjustments: HsmnCod Conclusion In this guide, we learned how to delete characters from a string in Python using different methods, including regular expressions and slices. The choice of method depends on the specific task. For example, the replace() method is suitable for simpler cases, while re.sub() is better for more complex situations.
23 August 2025 · 5 min to read

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