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Quick-start with curl

Examples

Copy-pasteable requests for the most common operations. Replace your-mattermost-server.com with your server URL and <TOKEN> with a valid personal access token.

Log in and get a session token​

curl -i -X POST https://your-mattermost-server.com/api/v4/users/login \
  -H 'Content-Type: application/json' \
  -d '{
    "login_id": "user@example.com",
    "password": "yourpassword"
  }'

The session token is returned in the Token response header.

Post a message to a channel​

curl -X POST https://your-mattermost-server.com/api/v4/posts \
  -H 'Authorization: Bearer <TOKEN>' \
  -H 'Content-Type: application/json' \
  -d '{
    "channel_id": "<CHANNEL_ID>",
    "message": "Status update from API"
  }'

Create a channel​

curl -X POST https://your-mattermost-server.com/api/v4/channels \
  -H 'Authorization: Bearer <TOKEN>' \
  -H 'Content-Type: application/json' \
  -d '{
    "team_id": "<TEAM_ID>",
    "name": "ops-incident-2026-05",
    "display_name": "Ops Incident — 2026-05",
    "type": "O"
  }'

Add a user to a channel​

curl -X POST https://your-mattermost-server.com/api/v4/channels/<CHANNEL_ID>/members \
  -H 'Authorization: Bearer <TOKEN>' \
  -H 'Content-Type: application/json' \
  -d '{ "user_id": "<USER_ID>" }'

Upload a file​

curl -X POST https://your-mattermost-server.com/api/v4/files \
  -H 'Authorization: Bearer <TOKEN>' \
  -F 'channel_id=<CHANNEL_ID>' \
  -F 'files=@./report.pdf'

Trigger a slash command​

curl -X POST https://your-mattermost-server.com/api/v4/commands/execute \
  -H 'Authorization: Bearer <TOKEN>' \
  -H 'Content-Type: application/json' \
  -d '{
    "channel_id": "<CHANNEL_ID>",
    "command": "/echo Hello from the API"
  }'