Slack

Slack

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

Quick Start

# 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:

export MATON_API_KEY="YOUR_API_KEY"

Getting Your API Key

1. Sign in or create an account at maton.ai
2. Go to maton.ai/settings
3. Copy your API key

Connection Management

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

List Connections

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

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

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:

{
  "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

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:

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

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

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

With blocks:

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

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

Post Thread Reply

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

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

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

Delete Message

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

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

List Channels

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

Get Channel Info

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

Get Channel Members

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

List Messages in Channel

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

Get Thread Replies

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

List Users

GET /slack/api/users.list

Get User Info

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

Search Messages

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

Open DM Conversation

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

{
  "users": "U0123456789"
}

Add Reaction

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

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

Upload File

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:

GET /slack/api/auth.test

Code Examples

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

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

Troubleshooting: Invalid API Key

When you receive a "Invalid API key" error, ALWAYS follow these steps before concluding there is an issue:

1. Check that the MATON_API_KEY environment variable is set:

echo $MATON_API_KEY

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

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

Resources

• Slack API Overview
• Post Message
• Update Message
• Delete Message
• List Channels
• Channel History
• Thread Replies
• List Users
• Get User Info
• Search Messages
• Block Kit Reference
• LLM Reference