PolyBot Quickstart: Build an Echo Bot in Minutes

Create a working Telegram echo bot with PolyBot — write handlers, register the generated router, and start long polling in a few steps.

This guide walks you through building a minimal echo bot from scratch. By the end you will have a working Telegram bot that greets users on /start and echoes every other message back. The complete source is based on the EchoBot sample shipped with PolyBot.

Before you start, make sure you have the PolyBot NuGet package installed and that your project’s OutputType is Exe. See Installation for details.

Prerequisites

• .NET 8 or later (the PolyBot package targets netstandard2.0 and net10.0)
• A Telegram bot token from @BotFather

Full example

The listing below is the complete EchoBot Program.cs. The sections that follow break it apart step by step.

using Microsoft.Extensions.Configuration;
using PolyBot;
using PolyBot.Attributes;
using PolyBot.Routing;
using Telegram.Bot;
using Telegram.Bot.Types;
using Telegram.Bot.Types.ReplyMarkups;

namespace EchoBot;

public sealed partial class BotHandlers
{
    [CallbackButton("Help", "help"), CallbackButton("About", "about")]
    private static partial InlineKeyboardMarkup StartKeyboard();

    [MessageHandler(Priority = -1)]
    [Command(Aliases = ["start"], Description = "Start the bot")]
    public static async Task<Result> Start(Message msg, ITelegramBotClient bot, CancellationToken ct)
    {
        await bot.SendMessage(msg.Chat.Id, "Welcome! I echo everything you say.", replyMarkup: StartKeyboard(), cancellationToken: ct);
        return Result.Handled();
    }

    [MessageHandler(Priority = 0)]
    public static async Task<Result> Echo(Message msg, ITelegramBotClient bot, CancellationToken ct)
    {
        await bot.SendMessage(msg.Chat.Id, msg.Text ?? string.Empty, cancellationToken: ct);
        return Result.Handled();
    }
}

public static class Program
{
    public static async Task Main(string[] args)
    {
        string? token = args.Length > 0 ? args[0] : Environment.GetEnvironmentVariable("TELEGRAM_BOT_TOKEN");
        if (string.IsNullOrEmpty(token))
        {
            throw new InvalidOperationException(
                "No bot token provided: pass it as the first argument or set the TELEGRAM_BOT_TOKEN environment variable.");
        }

        PolyBotClient client = new PolyBotClient(new PolyBotOptions() { BotToken = token });
        client.Services.AddPolyBotRouter();

        await client.RunPollingAsync();
    }
}

Step-by-step walkthrough

Running the bot

# Pass the token as a command-line argument
dotnet run -- YOUR_BOT_TOKEN

# Or set the environment variable and run without arguments
export TELEGRAM_BOT_TOKEN=YOUR_BOT_TOKEN
dotnet run

Send /start to your bot in Telegram — it should reply with the welcome message. Any other text message will be echoed back.

What to explore next

Installation

NuGet setup, project requirements, PolyBotOptions reference, and service wiring details.

Introduction

Full feature overview: FSM, filters, rate limiting, webhooks, and more.