Sending Messages with Raw HTTP POST Requests

In our previous lessons, we've built a solid conceptual model of the Telegram Bot API. You now understand the API's architecture, its core data structures like Update and Message, and the two mechanisms—long polling and webhooks—for receiving information from Telegram's servers.

This lesson transitions from theory to practice. We will perform our first active operation: sending a message. You will learn to directly call the sendMessage API method using a raw HTTP POST request. This fundamental skill is the bedrock upon which all bot interactions are built. We'll start with a simple curl command for quick verification and then translate that logic into a TypeScript script using Bun's native fetch API, directly leveraging your extensive front-end development experience.

The Anatomy of an API Method Call

All interactions with the Telegram Bot API happen over HTTPS. A request to execute a specific method follows a simple and consistent URL structure:

https://api.telegram.org/bot<TOKEN>/<METHOD_NAME>

• <TOKEN> is the unique authorization token you received from BotFather.
• <METHOD_NAME> is the name of the API method you wish to call, such as sendMessage.

For the sendMessage method, you must provide parameters specifying what to send and where to send it. The two most important parameters are:

• chat_id: The unique identifier for the target chat.
• text: The UTF-8 encoded text of the message.

Our first challenge is to find the chat_id for the conversation between you and your bot.

Prerequisite: Finding Your chat_id

The bot needs to know the destination for its message. To get your personal chat_id with the bot, you first need to initiate the conversation.

1. Start the Conversation: Open Telegram, find the bot you created, and send it a message (e.g., "hello"). This creates an Update event on Telegram's servers associated with your chat.

2. Fetch the Update: We can now use the getUpdates method to retrieve that Update object. The response will be a JSON array containing recent updates. Inside the message object of the latest update, you will find a chat object which contains your unique id.

The following images show the structure of the JSON response from the API. The chat.id is the value you need to retrieve.

You can retrieve this ID directly from your terminal. The following article provides a clear, hands-on guide. We will use its method for finding the chat ID and then for sending a message.

Store your bot token and the chat_id you just retrieved. We will use them as environment variables, following best practices.

Sending a Message with curl

Before writing any TypeScript, it's often useful to test an API endpoint with a simple curl command. This confirms that your token and chat_id are correct and that you understand the request structure, without any language-specific boilerplate.

The sendMessage method accepts a POST request. The parameters can be sent as either application/json or application/x-www-form-urlencoded. The curl command below uses the latter, which is slightly more direct for simple key-value data.

As an alternative, you can also send the data as a JSON payload. This approach is more verbose in curl but is closer to what we will do in our TypeScript code. The Gist below shows an example.

Sending a Message with Bun and TypeScript

Now, let's translate this raw HTTP request into a reusable TypeScript function. Given your background, this will feel very familiar. We'll use Bun's built-in, web-standard fetch API, which you've likely used extensively in front-end projects.

We will create a simple script, sendMessage.ts, that reads the bot token and chat ID from environment variables and sends a message.

The same article we've been using provides a perfect, ready-to-use TypeScript example that uses Bun.

To run this script, open your terminal in the project directory and execute the command provided at the end of the article section, replacing xxx with your bot token and yyy with your chat ID:

TELEGRAM_BOT_TOKEN=xxx TELEGRAM_CHAT_ID=yyy bun run sendMessage.ts

If everything is configured correctly, your bot will send you the message "Build passed ✅", with the word "passed" rendered in bold because the parse_mode was set to HTML.

Conclusion

In this lesson, you have successfully bridged the gap between API theory and practical execution. By making a raw HTTP request to the sendMessage method, you've directly communicated with your bot and commanded it to perform an action. This low-level understanding is invaluable, even when you start using a framework that abstracts these details away.

Key Takeaways:

• Telegram API methods are called via HTTPS POST requests to a URL in the format https://api.telegram.org/bot<TOKEN>/<METHOD_NAME>.
• The chat_id is a necessary parameter to target a specific conversation and can be found by inspecting the Update objects returned by the getUpdates method.
• You can test API endpoints directly from the command line using curl.
• You can translate curl commands into TypeScript using Bun's built-in fetch API, structuring the request with appropriate headers (Content-Type: application/json) and a JSON-serialized body.

We have now successfully sent a message from our code to Telegram. The next logical step is to have our bot react to messages it receives. In the next lesson, we will implement a basic long polling loop using getUpdates to create our first simple, interactive echo bot.