Social — entry 028 of 39
Slack
Slack's Web API lets registered apps read and post messages, manage channels, and react to workspace events, authenticated with OAuth 2.0 bot or user tokens scoped to a single Slack workspace. Methods are rate-limited across four tiers and most write actions cap out around one request per second per workspace, so high-throughput integrations typically move to the Events API or Socket Mode instead of polling.
AuthenticationOAuthRequires an OAuth flow; expect app registration.
HTTPSSupportedTraffic is encrypted in transit.
CORSEnabledCallable directly from browser JavaScript.
PricingFreeNo paid tier — free for the documented use case.
FormatsJSONResponses can be requested as JSON.
GreatAPIs Score
Score77
Authentication8/25OAuth flow required
Pricing20/20Free to use
Docs20/20Machine-readable spec file bundled
Formats9/15Single response format
Freshness20/20Verified within 6 months
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<a href="https://greatapis.com/api/slack/"><img src="https://greatapis.com/badge/slack.svg" alt="Scored 77 on greatapis.com"></a>Auth quickstart
- Register an app / run the OAuth flow to obtain a bearer token.
- Send it as an Authorization header
Authorization: Bearer <token>
Stored keyNo key stored
Your key is stored only in this browser (localStorage) and sent directly to the API — never to greatapis.
Endpoints
chat1
POST/chat.postMessage
Parameters
| Name | In | Required | Type |
|---|---|---|---|
token | header | yes | string |
Request body
application/x-www-form-urlencoded
Responses
| Status | Description | Schema |
|---|---|---|
200 | Typical success response | — |
default | Typical error response if too many attachments are included | — |
conversations4
POST/conversations.create
Parameters
| Name | In | Required | Type |
|---|---|---|---|
token | header | no | string |
Request body
application/x-www-form-urlencoded
Responses
| Status | Description | Schema |
|---|---|---|
200 | If successful, the command returns a rather stark [conversation object](/types/conversation) | — |
default | Typical error response when name already in use | — |
GET/conversations.history
Parameters
| Name | In | Required | Type |
|---|---|---|---|
token | query | no | string |
channel | query | no | string |
latest | query | no | number |
oldest | query | no | number |
inclusive | query | no | boolean |
limit | query | no | integer |
cursor | query | no | string |
Responses
| Status | Description | Schema |
|---|---|---|
200 | Typical success response containing a channel's messages | — |
default | Typical error response | — |
GET/conversations.info
Parameters
| Name | In | Required | Type |
|---|---|---|---|
token | query | no | string |
channel | query | no | string |
include_locale | query | no | boolean |
include_num_members | query | no | boolean |
Responses
| Status | Description | Schema |
|---|---|---|
200 | Typical success response for a public channel. (Also, a response from a private channel and a multi-party IM is very similar to this example.) | — |
default | Typical error response when a channel cannot be found | — |
GET/conversations.list
Parameters
| Name | In | Required | Type |
|---|---|---|---|
token | query | no | string |
exclude_archived | query | no | boolean |
types | query | no | string |
limit | query | no | integer |
cursor | query | no | string |
Responses
| Status | Description | Schema |
|---|---|---|
200 | Typical success response with only public channels | — |
default | Typical error response | — |
files1
POST/files.upload
Request body
application/x-www-form-urlencoded
Responses
| Status | Description | Schema |
|---|---|---|
200 | Success response after uploading a file to a channel with an initial message | — |
default | Typical error response | — |
reactions1
POST/reactions.add
Parameters
| Name | In | Required | Type |
|---|---|---|---|
token | header | yes | string |
Request body
application/x-www-form-urlencoded (required)
Responses
| Status | Description | Schema |
|---|---|---|
200 | Typical success response | — |
default | Typical error response | — |
search1
GET/search.messages
Parameters
| Name | In | Required | Type |
|---|---|---|---|
token | query | yes | string |
count | query | no | integer |
highlight | query | no | boolean |
page | query | no | integer |
query | query | yes | string |
sort | query | no | string |
sort_dir | query | no | string |
Responses
| Status | Description | Schema |
|---|---|---|
200 | Typical success response | — |
default | Typical error response | — |
users2
GET/users.info
Parameters
| Name | In | Required | Type |
|---|---|---|---|
token | query | yes | string |
include_locale | query | no | boolean |
user | query | no | string |
Responses
| Status | Description | Schema |
|---|---|---|
200 | Typical success response | — |
default | Typical error response | — |
GET/users.list
Parameters
| Name | In | Required | Type |
|---|---|---|---|
token | query | no | string |
limit | query | no | integer |
cursor | query | no | string |
include_locale | query | no | boolean |
Responses
| Status | Description | Schema |
|---|---|---|
200 | Typical success response | — |
default | Typical error response | — |
Try it
Developer reference
Base URL
https://slack.com/apiRate limit
Tiered per method (Tier 1-4); most methods are capped around 1 request/second per workspace
Key endpoints
- POST/chat.postMessage
- GET/conversations.list
- GET/conversations.history
- GET/users.info