4chan · Rate Limits

4Chan Rate Limits

4chan publishes hard client-side rate-limit rules in the API README that all clients MUST observe. The limits are per-client (enforced by IP at the network edge) and apply uniformly regardless of who is calling — there is no per-account scoping because there is no authentication. Two rules dominate: no more than one request per second across all endpoints, and any per-thread polling loop must wait at least 10 seconds (preferably longer) between requests against `/{board}/thread/{thread}.json`. Clients SHOULD also send `If-Modified-Since` so unchanged threads are served as `304 Not Modified` and do not count against an effective fetch budget.

4Chan Rate Limits is the machine-readable rate-limit profile for 4chan on the APIs.io network, conforming to the API Commons Rate Limits specification.

It captures 4 rate-limit definitions, measuring requests_per_second, requests_per_minute, and varies.

The profile also includes 5 backoff/retry policies defined and response codes documented for notModified, notFound, and throttled.

Tagged areas include Rate Limiting, Social, Imageboard, and Read Only.

4 Limits Throttle: 503
Rate LimitingSocialImageboardRead Only

Limits

Global request rate (all endpoints) IP
requests_per_second · second
1
Hard rule from the 4chan API README: "Do not make more than one request per second." Applies across all endpoints.
Per-thread polling interval IP
requests_per_minute · minute
6
Rule from the 4chan API README: "Thread updating should be set to a minimum of 10 seconds, preferably higher." 6 req/min is the absolute ceiling for a single thread.json polling loop; 1–2 req/min is preferred.
HTTP methods accepted IP
varies
Only GET / HEAD / OPTIONS — POST / PUT / PATCH / DELETE are rejected
The API is read-only. Any non-read method returns an error at the edge.
CORS allowed origins IP
varies
CORS allowed only from boards.4chan.org and boards.4channel.org
Cross-origin requests from any other origin are blocked. Server-side clients are unaffected.

Policies

Use If-Modified-Since
Per the 4chan API rules, clients SHOULD send `If-Modified-Since` on repeated requests. A `304 Not Modified` response indicates the resource has not changed since the supplied timestamp; clients MUST keep their cached copy and avoid re-parsing the body.
Match protocol of the calling app
"Make API requests using the same protocol as the app. Only use SSL when a user is accessing your app over HTTPS." This is a published rule in the 4chan API README.
Back off on 503
503 responses indicate the edge is shedding load. Exponential back off and respect any `Retry-After` header if present.
Use threads.json for change detection
Poll `/{board}/threads.json` (small, cheap) to detect which thread ids have a newer `last_modified` before fetching the full thread document. This is the canonical efficient polling pattern.
Anonymous and unauthenticated
There is no API key, token, or account. Rate limits are per-IP and cannot be raised via support; high-volume use cases (research mirrors, archives) must spread requests over time, not parallelize across keys.

Sources

Work with this as data

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Tools for rate limits

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