Rate limit tiers, Retry-After and event limits
How Slack rate limits work and how an app should react: Web API tiers per method, per workspace, per app in per-minute windows, HTTP 429 with Retry-After scoped to one method and workspace, about one message per second per channel, stricter limits without pagination, the 2025 conversations.history change for unlisted apps, and the 30,000-event Events API cap with app_rate_limited.
Process rate limits throughout the Slack platform.
~7 min read · 5 practice questions ·
What the exam expects
- Explain how Web API limits are applied: per method, per workspace, per app, in per-minute windows, with the tier listed in each method's Facts.
- Handle HTTP 429 by waiting the
Retry-Afterseconds for that method and workspace only, while other calls continue. - Keep message posting near one message per second per channel and consolidate bursts.
- Paginate collection methods with sensible limits to get the published rate limit rather than stricter unpaginated limits.
- Recognise
app_rate_limitedas the Events API delivery cap of 30,000 events per workspace per app per 60 minutes, distinct from failure-based disabling.
Key terms: rate limit tier (Tier 1-4 or special, the request allowance assigned to a method), HTTP 429 (Too Many Requests), Retry-After (header with the seconds to wait), burst (short spikes above the limit that Slack tolerates), app_rate_limited (the event Slack sends while event deliveries are capped).
Key facts
- Detail
- Per method, per workspace, per app
- Detail
- Per minute
- Detail
- Facts section of the method reference
- Detail
- All plans get the same tier per method
- Detail
- HTTP 429 with
Retry-Afterin seconds
- Detail
- Same method, same workspace, any of its tokens
- Detail
- About 1 message per second per channel; webhooks too
chat.postMessage- Detail
- Special tier; several hundred per minute workspace-wide
- Detail
- Stricter limits than the published tier
- Detail
- New apps and new installs since May 29, 2025:
conversations.historyandconversations.repliesat 1 per minute, 15 objects
- Detail
- 30,000 per workspace per app per 60 minutes
- Why doesn't a 429 on one workspace stop the same call for another workspace?
- Where do you find a method's rate-limit tier?
- When does an app receive `app_rate_limited`?
- Why paginate `users.list` instead of fetching it all at once?
- What history-method limits apply to a new install of an unlisted, commercially distributed app?
The questions are free to read. Answers with their sources and self-grading are included with the pack.
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