# Telegram Webhooks

## When to Use This Skill

* How do I receive Telegram bot updates with a webhook instead of `getUpdates`?
* How do I verify that a Telegram webhook request really came from Telegram?
* How do I check the `X-Telegram-Bot-Api-Secret-Token` header?
* How do I handle `message`, `callback_query`, or `inline_query` updates?
* Why does Telegram keep retrying my webhook, or why is `pending_update_count` growing?

## How Telegram Webhook Verification Works

Telegram does **not** sign webhook payloads. There is no HMAC and no signature header.
Instead, you pass a `secret_token` (1-256 characters, only `A-Z`, `a-z`, `0-9`, `_`
and `-`) when you call [`setWebhook`](https://core.telegram.org/bots/api#setwebhook).
Telegram then sends that exact value in the `X-Telegram-Bot-Api-Secret-Token` header
on every webhook request. Your handler compares it to the expected value with a
constant-time comparison and rejects anything that doesn't match.

* The token covers the request as a whole, not the body, so there is nothing to compute
  over the raw body. Parse the JSON only after the token check passes.
* If you call `setWebhook` without `secret_token`, the header is not sent at all.
* Optional defense in depth: Telegram sends from `149.154.160.0/20` and `91.108.4.0/22`.

## Verification (core)

```javascript
const crypto = require('crypto');

// headerValue: req.headers['x-telegram-bot-api-secret-token']
function verifyTelegramSecretToken(headerValue, expectedSecret) {
  if (!headerValue || !expectedSecret) return false;
  const received = Buffer.from(headerValue);
  const expected = Buffer.from(expectedSecret);
  // timingSafeEqual throws on length mismatch, so check length first
  return received.length === expected.length && crypto.timingSafeEqual(received, expected);
}

```

```python
import hmac

def verify_telegram_secret_token(header_value: str | None, expected: str) -> bool:
    if not header_value or not expected:
        return False
    return hmac.compare_digest(header_value.encode(), expected.encode())

```

> **For complete handlers with tests**, see [examples/express/](https://github.com/hookdeck/webhook-skills/tree/main/skills/telegram-webhooks/examples/express/), [examples/nextjs/](https://github.com/hookdeck/webhook-skills/tree/main/skills/telegram-webhooks/examples/nextjs/), [examples/fastapi/](https://github.com/hookdeck/webhook-skills/tree/main/skills/telegram-webhooks/examples/fastapi/).

## Common Update Types

Each webhook body is one JSON [`Update`](https://core.telegram.org/bots/api#update)
object. There is no `type` field: an update has `update_id` plus **at most one** of the
optional fields below, and you route on which one is present.

| Update field | Triggered when |
| --- | --- |
| `message` | New incoming message of any kind (text, photo, sticker, command, ...) |
| `edited_message` | A message known to the bot was edited |
| `channel_post` | New post in a channel where the bot is a member |
| `callback_query` | A user pressed an inline keyboard button |
| `inline_query` | A user typed `@yourbot ...` in any chat |
| `my_chat_member` | The bot's own membership changed (added, removed, blocked, unblocked) |

> **For the full list** (`chat_member`, `message_reaction`, `pre_checkout_query`, `poll_answer`, ...), see [references/overview.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/telegram-webhooks/references/overview.md).

## Important Headers

| Header | Description |
| --- | --- |
| `X-Telegram-Bot-Api-Secret-Token` | The `secret_token` you passed to `setWebhook`, sent as plain text. Only present if you set one |
| `Content-Type` | `application/json` |

## Environment Variables

```bash
TELEGRAM_WEBHOOK_SECRET=your_secret_token   # The secret_token passed to setWebhook
TELEGRAM_BOT_TOKEN=123456:ABC-DEF...        # Only needed to call setWebhook / the Bot API

```

## Local Development

```bash
# Start tunnel (no account needed)
npx hookdeck-cli listen 3000 telegram --path /webhooks/telegram

```

Then point the bot at the public URL (see [references/setup.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/telegram-webhooks/references/setup.md)).
Telegram only delivers to HTTPS URLs on ports 443, 80, 88 or 8443.

## Reference Materials

* [references/overview.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/telegram-webhooks/references/overview.md) - Telegram webhook concepts, Update types, payload structure
* [references/setup.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/telegram-webhooks/references/setup.md) - Create a bot, call `setWebhook`, check `getWebhookInfo`
* [references/verification.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/telegram-webhooks/references/verification.md) - Secret token verification, IP allowlist, gotchas