PUBLISHED PROVIDER LIMITS
Limits keep their provider-specific dimensions.
Slack assigns each Web API method to a rate tier and permits some burst behavior without publishing exact burst ceilings. Certain methods vary by app distribution.
Authentication: OAuth bot or user access token, App-level token where supported, Incoming webhook URL token
Primary scope: Method Per Workspace Per App
Measured dimensions: Requests, Messages, Events
Profile coverage: Web API tier minimums, message posting, Events API delivery, Retry-After behavior, and app-distribution-dependent controls. Method-specific burst tolerance and specialized workflow or AI limits remain outside this profile.
Web API Tier
| Limit | Value | Period | Scope | Conditions and variability |
|---|---|---|---|---|
| Web API Tier 1 published minimum | 1 requests | Per minute | Method Per Workspace Per App | Slack describes this as at least one request per minute and allows a small amount of burst behavior. |
| Web API Tier 2 published minimum | 20 requests | Per minute | Method Per Workspace Per App | Slack describes this as at least 20 requests per minute and allows occasional bursts. |
| Web API Tier 3 published minimum | 50 requests | Per minute | Method Per Workspace Per App | Slack describes this as at least 50 requests per minute and allows occasional bursts. |
| Web API Tier 4 published minimum | 100 requests | Per minute | Method Per Workspace Per App | Slack describes this as at least 100 requests per minute and allows generous bursts. |
Message Rate
| Limit | Value | Period | Scope | Conditions and variability |
|---|---|---|---|---|
| Message posting per channel | 1 messages | Per second | Channel | Slack generally permits short bursts and also applies a workspace-wide message limit. |
| Incoming webhook posting | 1 messages | Per second | Webhook | Short bursts are allowed. |
Event Delivery
| Limit | Value | Period | Scope | Conditions and variability |
|---|---|---|---|---|
| Events API delivery ceiling | 30,000 events | Per hour | App Per Workspace | Measured across a 60-minute period |
Distribution Specific
| Limit | Value | Period | Scope | Conditions and variability |
|---|---|---|---|---|
| App-distribution-dependent method limits | Provider-specific | Provider-defined | Method Per Workspace Per App | Selected conversation-history methods can use different limits for newly distributed non-Marketplace commercial apps and installations. |
RESPONSE METADATA
Headers expose the applicable limit state.
Retry-AfterFormat: Integer Seconds- Seconds to wait before calling the same Slack method for the same workspace again.
WHEN A LIMIT IS EXCEEDED
Read the response before choosing a delay.
- Rate-limit responses can use HTTP 429.
RECOMMENDED HANDLING
Protect both the provider and your own queue.
- Honor Retry-After for the affected method and workspace.
- Queue outbound messages and API work instead of depending on undocumented burst tolerance.
- Read the method's assigned tier and any app-distribution-specific rules.
- Handle app_rate_limited events when Events API delivery exceeds its ceiling.
VERIFICATION RECORD