specification: API Commons Rate Limits
specificationVersion: '0.1'
provider: Chess.com
providerId: chess-com
created: '2026-05-25'
modified: '2026-05-25'
tags:
  - Chess
  - Rate Limiting
  - Public API
description: Rate-limit posture for the Chess.com Published Data API. The API does not publish a numeric
  limit but enforces throttling on parallel requests.
sources:
  - https://www.chess.com/news/view/published-data-api
  - https://support.chess.com/en/articles/9650547-published-data-api
algorithm: parallel-request-throttle
responseCodes:
  throttled: 429
  notFound: 404
  gone: 410
authentication: none
headers:
  conditional:
    - If-Modified-Since
    - If-None-Match
  responseCaching:
    - ETag
    - Last-Modified
    - Cache-Control
policies:
  - name: Serial requests unlimited
    description: Serial (non-parallel) client traffic is unlimited in practice.
  - name: Parallel requests throttled
    description: Concurrent requests against the same path or against many paths in parallel will receive
      429 Too Many Requests responses. There is no published per-IP or per-key quota.
  - name: Cache refresh window
    description: Most endpoints refresh at most every 12-24 hours. Clients SHOULD honor ETag and
      Last-Modified to avoid revalidation traffic.
  - name: User-Agent requirement
    description: Clients SHOULD include a recognizable User-Agent header containing a contact email or
      URL. Generic or empty User-Agents may be blocked.
  - name: Stale-player tolerance
    description: About 3% of players still using legacy V2 website may have slightly stale data.
recommendations:
  - Use HTTP conditional GETs (If-Modified-Since, If-None-Match) to receive 304 Not Modified.
  - Back off exponentially on 429 (start at 60 seconds and double).
  - Avoid concurrent requests; serialize calls per host.
  - Cache responses for at least the documented 12-hour refresh window.