# Slack API

**Provider:** Slack
**Category:** communication
**Base URL:** `https://slack.com/api`
**Auth:** bearer — `Authorization: Bearer xoxb-...`
**Rate Limit:** 1 request/s per method (Tier 1)
**Free Tier:** Yes — [object Object]
**Pricing:** Free tier available (freemium)
**Docs:** https://api.slack.com/docs

## Description

The Slack API lets you build bots, post to channels, respond to slash commands, open modals, react to events via webhooks, search messages, manage users and channels, and create interactive workflows. Available as REST API or via the Bolt SDK.

## Endpoints

| Method | Endpoint | Description |
|--------|----------|-------------|
| POST | `https://slack.com/api/chat.postMessage` | Send a message to a channel or DM |
| GET | `https://slack.com/api/conversations.history` | Fetch conversation history |
| GET | `https://slack.com/api/conversations.list` | List all channels in workspace |
| POST | `https://slack.com/api/views.open` | Open a modal view |
| POST | `https://slack.com/api/reactions.add` | Add an emoji reaction to a message |
| GET | `https://slack.com/api/users.list` | List workspace members |

## Authentication

Use OAuth 2.0 access tokens (user or bot) as Bearer tokens. Webhook URLs work without tokens.

```
Authorization: Bearer xoxb-...
```

## Sample Request

```bash
curl -X POST https://slack.com/api/chat.postMessage \
  -H "Authorization: Bearer $SLACK_BOT_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "channel": "C0123456789",
    "text": "Hello from the API!",
    "blocks": [{"type":"section","text":{"type":"mrkdwn","text":"*Bold* and _italic_"}}]
  }'
```

## Sample Response

```json
{
  "ok": true,
  "channel": "C0123456789",
  "ts": "1716249600.123456",
  "message": {
    "type": "message",
    "text": "Hello from the API!",
    "bot_id": "B0123456789",
    "ts": "1716249600.123456"
  }
}
```

## Pricing Details

Slack API usage is free. Slack workspace plans: Free (90-day message history), Pro $7.25/user/mo, Business+ $12.50/user/mo. Rate limits tighten on free tier.

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*Source: [API Map](https://apimap.dev/apis/slack/) — CC BY 4.0*