name: NASA CMR Rate Limits
description: >
  Rate limiting details for the NASA Common Metadata Repository (CMR) APIs.
  CMR Search enforces throttling rules per request signature to maintain
  system availability. Specific numeric thresholds are not published; clients
  must honor 429 responses with the retry-after header.
url: https://cmr.earthdata.nasa.gov/search/site/docs/search/api.html

limits:

  - plan: Public Search (Anonymous)
    type: throttling
    scope: request signature / IP
    notes: >
      CMR Search deploys rate throttling rules targeting specific request
      signatures to prevent system degradation. No fixed request-per-second
      figure is published. 429 errors include a retry-after header; clients
      must honor this value before retrying.

  - plan: Authenticated Search (EDL Token)
    type: throttling
    scope: request signature / token
    notes: >
      Same throttling framework applies to authenticated requests. EDL tokens
      do not unlock a separate higher-rate tier for search; authentication
      primarily controls access to restricted content.

  - plan: All Plans
    type: request-timeout
    value: 180
    unit: seconds
    notes: >
      Hard request timeout is 180 seconds. An internal query timeout of
      170 seconds returns partial results with a warning header rather than
      an error, allowing clients to page through large result sets.

  - plan: All Plans
    type: page-size
    max: 2000
    default: 10
    notes: >
      Maximum page size is 2,000 results per request. Default is 10.
      Deep paging beyond 1 million items is not supported.

  - plan: All Plans
    type: deep-paging-limit
    max: 1000000
    notes: >
      Stateless deep paging via the CMR-Search-After response header supports
      up to 1 million items. The deprecated scroll API has been removed.

  - plan: All Plans
    type: url-length
    max: 6000
    unit: characters
    notes: >
      GET requests are limited to 6,000 characters. Browser clients are
      limited to ~2,000 characters. POST requests should be used for
      complex queries exceeding these limits.

enforcement:
  description: >
    Rate throttling is enforced via HTTP 429 status codes. The retry-after
    response header specifies the number of seconds to wait before retrying.
    Clients should implement exponential back-off and include a Client-Id
    header to help NASA identify and assist high-volume users.
  headers:
    - name: retry-after
      description: Seconds to wait before retrying after a 429 response
    - name: CMR-Hits
      description: Total number of matching results for the query
    - name: CMR-Request-Id
      description: Unique request identifier for debugging and support
    - name: Client-Id
      description: >
        Recommended request header for identifying your application;
        helps NASA diagnose issues for specific client traffic

contact:
  description: >
    High-volume users or data providers experiencing persistent throttling
    should contact NASA Earthdata support or post on the Earthdata Forum.
  url: https://forum.earthdata.nasa.gov/
  email: support@earthdata.nasa.gov