Overview

The 4chan API provides read-only, public access to boards, threads, and posts on 4chan with no authentication required. You can retrieve thread lists, individual posts, and board catalogs in JSON format. It is a great beginner-friendly API for learning how to parse JSON responses and build a simple reader app.

Beginner Tip

The 4chan API has strict rate limits — wait at least 1 second between requests to the same board and at least 10 seconds between full thread list fetches. Ignoring this will get your IP temporarily banned.

Available Data

The kind of data this API exposes, based on its documentation. We could not call the endpoint to confirm the exact field names.

thread and post listings
message content
user information
timestamps

Example Response

Illustrative shape only — we were not able to call this endpoint (it requires credentials or exposes no public sample URL), so the fields below show the kind of data this API returns rather than a recorded response.

JSON Response · Illustrative
{
  "page": 1,
  "threads": [
    {
      "no": 123456789,
      "sub": "Example Thread",
      "com": "Discussion content...",
      "time": 1705320000,
      "replies": 42
    }
  ]
}

Field Reference

no Unique post number within the board, used to reference individual posts.
com HTML-encoded body text of the post comment.
sub Subject line of the thread, only present on the opening post if set.
tim Unix timestamp used as part of the filename for any image attached to the post.
replies Number of replies the thread has received.
images Number of image replies in the thread.

Implementation Example

Calls a real endpoint of this API. Replace any placeholder credentials with your own key.

Request
const url = "https://a.4cdn.org/g/catalog.json";
const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data);

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

Common Errors & Troubleshooting

Generated guidance based on this API's documentation, not observed by us. Treat it as a starting point and check against the provider's own error reference.

404 Not Found The board abbreviation or thread number does not exist, or the thread has been archived or deleted.
Check the board abbreviation is correct (e.g., "g" for technology) and confirm the thread is still active via the catalog endpoint.
429 Too Many Requests You are sending requests too quickly and have been rate-limited.
Add a delay of at least 1 second between requests. For catalog and thread list endpoints, wait at least 10 seconds between refreshes.
Empty or null fields Some post fields such as sub (subject) or com (comment) are optional and may be absent.
Always check if a field exists before accessing it in your code, using optional chaining or null checks.

Metadata Score Breakdown

Estimated from metadata — endpoint not independently tested

This score is estimated from observable metadata — HTTPS support, authentication model, declared CORS, and documentation reachability — because the API requires authentication or exposes no publicly testable endpoint. The five-signal breakdown is only shown for live-tested APIs.

Metadata estimate · endpoint not independently tested

Technical Specifications

Auth No Auth
HTTPS REQUIRED
CORS YES
Category Social
Difficulty Beginner
Listing details not endpoint-verified

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