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, in the API Commons Rate Limits shape.

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

Limit state is signalled in the ifModifiedSince and lastModified response headers, and an exhausted limit returns HTTP 503.

This profile was written by API Evangelist and has not been verified against a page the provider published; treat every limit as unconfirmed until a dated transcription replaces it.

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 Exhausted: HTTP 503 ifModifiedSincelastModified
Method: generated, dated 2026-05-28.
Written by API Evangelist on 2026-05-28 and not verified against a page the provider published. Treat every limit as unconfirmed until a dated transcription replaces it.
View Source
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

Every rate limit here is available over the APIs.io API and to AI agents over MCP.

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Tools for rate limits

4 MCP tools reach this
  • find_rate_limitsBrowse and filter every rate limit in the catalog.
  • apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
  • resolveTurn a domain, URL or GitHub org into the provider it belongs to.
  • find_cohortsEvery scored population of providers in the catalog.
All 92 tools →

Call it yourself

curl for this page
This rate limit 
curl "https://apis.io/api/v1/rate-limits/4chan-rate-limits"
All rate limits 
curl "https://apis.io/api/v1/rate-limits?limit=25"

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