name: Smithsonian Open Access API Rate Limits
description: Rate limits for the Smithsonian Open Access API are managed through
  api.data.gov, the US Government's shared API management infrastructure. Limits
  vary by authentication tier. All limits reset on a rolling hourly basis.
url: https://api.data.gov/docs/developer-manual/
created: '2026-06-13'
modified: '2026-06-13'
rateLimits:
  - tier: DEMO_KEY
    description: Rate limits for unauthenticated access using the DEMO_KEY (no registration required)
    limits:
      - type: requests
        period: hour
        limit: 30
        unit: per IP address
        enforcement: HTTP 429 Too Many Requests
      - type: requests
        period: day
        limit: 50
        unit: per IP address
        enforcement: HTTP 429 Too Many Requests
    headers:
      - name: X-RateLimit-Limit
        description: Your current hourly rate limit ceiling
      - name: X-RateLimit-Remaining
        description: Number of requests remaining in the current hour window
    resetPolicy: Rolling hourly; blocks lift automatically after one hour
  - tier: Standard API Key
    description: Rate limits for registered developers with a personal API key from api.data.gov
    limits:
      - type: requests
        period: hour
        limit: 1000
        unit: per API key
        enforcement: HTTP 429 Too Many Requests
    headers:
      - name: X-RateLimit-Limit
        description: Your current hourly rate limit ceiling (1000 for standard keys)
      - name: X-RateLimit-Remaining
        description: Number of requests remaining in the current hour window
    resetPolicy: Rolling hourly; blocks lift automatically after one hour
  - tier: High-Volume (Custom)
    description: Custom rate limits negotiated directly with the Smithsonian for high-volume consumers
    limits:
      - type: requests
        period: hour
        limit: Custom
        unit: negotiated
        enforcement: Per custom agreement
    contact: openaccess@si.edu
authentication:
  methods:
    - type: HTTP Header
      header: X-Api-Key
      example: "X-Api-Key: YOUR_API_KEY_HERE"
    - type: Query Parameter
      parameter: api_key
      example: "https://api.si.edu/openaccess/api/v1.0/search?q=moon&api_key=YOUR_KEY"
    - type: HTTP Basic Auth
      description: Pass API key as username with an empty password field
  registration: https://api.data.gov/signup/
  keyFormat: 40-character alphanumeric string
  transport: HTTPS required for all requests
errorHandling:
  rateLimitExceeded:
    httpStatus: 429
    description: Too Many Requests - rate limit exceeded
    resolution: Wait for the rolling hourly window to reset; reduce request frequency
  unauthenticated:
    httpStatus: 403
    description: Forbidden - missing or invalid API key
    resolution: Register at api.data.gov/signup and include a valid API key
bulkDataAlternative:
  description: For bulk access, the full dataset is available as a free AWS S3 dataset
    that avoids API rate limits entirely
  bucket: s3://smithsonian-open-access
  region: us-west-2
  access: No authentication required (--no-sign-request)
  updateSchedule: Weekly
  command: "aws s3 ls --no-sign-request s3://smithsonian-open-access/"