# Slack

> Slack API integration with managed OAuth. Send messages, manage channels, search conversations, and interact with Slack workspaces. Use this skill when users want to post messages, list channels, get user info, or automate Slack workflows. For other third party apps, use the api-gateway skill (https://clawhub.ai/byungkyu/api-gateway).

- Skill: `modbender/slack-3` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add modbender/slack-3`
- Raw SKILL.md: https://api.skillmd.com/api/skills/modbender/slack-3/raw
- Safety review: pending (external: skill-scanner WARNING, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: modbender (https://skillmd.com/u/modbender)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/modbender/slack-3

---


# Slack

Access the Slack API with managed OAuth authentication. Send messages, manage channels, list users, and automate Slack workflows.

## Quick Start

```bash
# Post a message to a channel
python <<'EOF'
import urllib.request, os, json
data = json.dumps({'channel': 'C0123456789', 'text': 'Hello from Maton!'}).encode()
req = urllib.request.Request('https://gateway.maton.ai/slack/api/chat.postMessage', data=data, method='POST')
req.add_header('Authorization', f'Bearer {os.environ["MATON_API_KEY"]}')
req.add_header('Content-Type', 'application/json')
print(json.dumps(json.load(urllib.request.urlopen(req)), indent=2))
EOF
```

## Base URL

```
https://gateway.maton.ai/slack/{method}
```

The gateway proxies requests to `slack.com` and automatically injects your OAuth token.

## Authentication

All requests require the Maton API key in the Authorization header:

```
Authorization: Bearer $MATON_API_KEY
```

**Environment Variable:** Set your API key as `MATON_API_KEY`:

```bash
export MATON_API_KEY="YOUR_API_KEY"
```

### Getting Your API Key

1. Sign in or create an account at [maton.ai](https://maton.ai)
2. Go to [maton.ai/settings](https://maton.ai/settings)
3. Copy your API key

## Connection Management

Manage your Slack OAuth connections at `https://ctrl.maton.ai`.

### List Connections

```bash
python <<'EOF'
import urllib.request, os, json
req = urllib.request.Request('https://ctrl.maton.ai/connections?app=slack&status=ACTIVE')
req.add_header('Authorization', f'Bearer {os.environ["MATON_API_KEY"]}')
print(json.dumps(json.load(urllib.request.urlopen(req)), indent=2))
EOF
```

### Create Connection

```bash
python <<'EOF'
import urllib.request, os, json
data = json.dumps({'app': 'slack'}).encode()
req = urllib.request.Request('https://ctrl.maton.ai/connections', data=data, method='POST')
req.add_header('Authorization', f'Bearer {os.environ["MATON_API_KEY"]}')
req.add_header('Content-Type', 'application/json')
print(json.dumps(json.load(urllib.request.urlopen(req)), indent=2))
EOF
```

### Get Connection

```bash
python <<'EOF'
import urllib.request, os, json
req = urllib.request.Request('https://ctrl.maton.ai/connections/{connection_id}')
req.add_header('Authorization', f'Bearer {os.environ["MATON_API_KEY"]}')
print(json.dumps(json.load(urllib.request.urlopen(req)), indent=2))
EOF
```

**Response:**
```json
{
  "connection": {
    "connection_id": "21fd90f9-5935-43cd-b6c8-bde9d915ca80",
    "status": "ACTIVE",
    "creation_time": "2025-12-08T07:20:53.488460Z",
    "last_updated_time": "2026-01-31T20:03:32.593153Z",
    "url": "https://connect.maton.ai/?session_token=...",
    "app": "slack",
    "metadata": {}
  }
}
```

Open the returned `url` in a browser to complete OAuth authorization.

### Delete Connection

```bash
python <<'EOF'
import urllib.request, os, json
req = urllib.request.Request('https://ctrl.maton.ai/connections/{connection_id}', method='DELETE')
req.add_header('Authorization', f'Bearer {os.environ["MATON_API_KEY"]}')
print(json.dumps(json.load(urllib.request.urlopen(req)), indent=2))
EOF
```

### Specifying Connection

If you have multiple Slack connections, specify which one to use with the `Maton-Connection` header:

```bash
python <<'EOF'
import urllib.request, os, json
data = json.dumps({'channel': 'C0123456789', 'text': 'Hello!'}).encode()
req = urllib.request.Request('https://gateway.maton.ai/slack/api/chat.postMessage', data=data, method='POST')
req.add_header('Authorization', f'Bearer {os.environ["MATON_API_KEY"]}')
req.add_header('Maton-Connection', '21fd90f9-5935-43cd-b6c8-bde9d915ca80')
req.add_header('Content-Type', 'application/json')
print(json.dumps(json.load(urllib.request.urlopen(req)), indent=2))
EOF
```

If omitted, the gateway uses the default (oldest) active connection.

## API Reference

### Post Message

```bash
POST /slack/api/chat.postMessage
Content-Type: application/json

{
  "channel": "C0123456789",
  "text": "Hello, world!"
}
```

With blocks:

```bash
POST /slack/api/chat.postMessage
Content-Type: application/json

{
  "channel": "C0123456789",
  "blocks": [
    {"type": "section", "text": {"type": "mrkdwn", "text": "*Bold* and _italic_"}}
  ]
}
```

### Post Thread Reply

```bash
POST /slack/api/chat.postMessage
Content-Type: application/json

{
  "channel": "C0123456789",
  "thread_ts": "1234567890.123456",
  "text": "This is a reply in a thread"
}
```

### Update Message

```bash
POST /slack/api/chat.update
Content-Type: application/json

{
  "channel": "C0123456789",
  "ts": "1234567890.123456",
  "text": "Updated message"
}
```

### Delete Message

```bash
POST /slack/api/chat.delete
Content-Type: application/json

{
  "channel": "C0123456789",
  "ts": "1234567890.123456"
}
```

### List Channels

```bash
GET /slack/api/conversations.list?types=public_channel,private_channel
```

### Get Channel Info

```bash
GET /slack/api/conversations.info?channel=C0123456789
```

### Get Channel Members

```bash
GET /slack/api/conversations.members?channel=C0123456789&limit=100
```

### List Messages in Channel

```bash
GET /slack/api/conversations.history?channel=C0123456789&limit=100
```

### Get Thread Replies

```bash
GET /slack/api/conversations.replies?channel=C0123456789&ts=1234567890.123456
```

### List Users

```bash
GET /slack/api/users.list
```

### Get User Info

```bash
GET /slack/api/users.info?user=U0123456789
```

### Search Messages

```bash
GET /slack/api/search.messages?query=keyword
```

### Open DM Conversation

```bash
POST /slack/api/conversations.open
Content-Type: application/json

{
  "users": "U0123456789"
}
```

### Add Reaction

```bash
POST /slack/api/reactions.add
Content-Type: application/json

{
  "channel": "C0123456789",
  "name": "thumbsup",
  "timestamp": "1234567890.123456"
}
```

### Upload File

```bash
POST /slack/api/files.upload
Content-Type: multipart/form-data

channels=C0123456789
content=file content here
filename=example.txt
```

### Auth Test

Get current user and team info:

```bash
GET /slack/api/auth.test
```

## Code Examples

### JavaScript

```javascript
const response = await fetch('https://gateway.maton.ai/slack/api/chat.postMessage', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'Authorization': `Bearer ${process.env.MATON_API_KEY}`
  },
  body: JSON.stringify({ channel: 'C0123456', text: 'Hello!' })
});
```

### Python

```python
import os
import requests

response = requests.post(
    'https://gateway.maton.ai/slack/api/chat.postMessage',
    headers={'Authorization': f'Bearer {os.environ["MATON_API_KEY"]}'},
    json={'channel': 'C0123456', 'text': 'Hello!'}
)
```

## Notes

- Channel IDs start with `C` (public), `G` (private/group), or `D` (DM)
- User IDs start with `U`, Team IDs start with `T`
- Message timestamps (`ts`) are used as unique identifiers
- Use `mrkdwn` type for Slack-flavored markdown formatting
- Thread replies use `thread_ts` to reference the parent message
- IMPORTANT: When using curl commands, use `curl -g` when URLs contain brackets (`fields[]`, `sort[]`, `records[]`) to disable glob parsing
- IMPORTANT: When piping curl output to `jq` or other commands, environment variables like `$MATON_API_KEY` may not expand correctly in some shell environments. You may get "Invalid API key" errors when piping.

## Error Handling

| Status | Meaning |
|--------|---------|
| 400 | Missing Slack connection |
| 401 | Invalid or missing Maton API key |
| 429 | Rate limited (10 req/sec per account) |
| 4xx/5xx | Passthrough error from Slack API |

### Troubleshooting: API Key Issues

1. Check that the `MATON_API_KEY` environment variable is set:

```bash
echo $MATON_API_KEY
```

2. Verify the API key is valid by listing connections:

```bash
python <<'EOF'
import urllib.request, os, json
req = urllib.request.Request('https://ctrl.maton.ai/connections')
req.add_header('Authorization', f'Bearer {os.environ["MATON_API_KEY"]}')
print(json.dumps(json.load(urllib.request.urlopen(req)), indent=2))
EOF
```

### Troubleshooting: Invalid App Name

1. Ensure your URL path starts with `slack`. For example:

- Correct: `https://gateway.maton.ai/slack/api/chat.postMessage`
- Incorrect: `https://gateway.maton.ai/api/chat.postMessage`

## Resources

- [Slack API Overview](https://api.slack.com/apis)
- [Post Message](https://api.slack.com/methods/chat.postMessage)
- [Update Message](https://api.slack.com/methods/chat.update)
- [Delete Message](https://api.slack.com/methods/chat.delete)
- [List Channels](https://api.slack.com/methods/conversations.list)
- [Channel History](https://api.slack.com/methods/conversations.history)
- [Thread Replies](https://api.slack.com/methods/conversations.replies)
- [List Users](https://api.slack.com/methods/users.list)
- [Get User Info](https://api.slack.com/methods/users.info)
- [Search Messages](https://api.slack.com/methods/search.messages)
- [Block Kit Reference](https://api.slack.com/reference/block-kit)
- [LLM Reference](https://docs.slack.dev/llms.txt)
- [Maton Community](https://discord.com/invite/dBfFAcefs2)
- [Maton Support](mailto:support@maton.ai)