generated: '2026-08-11'
method: probed
source: https://underscoredone.com/llms.txt + 26 service pages + live POST to https://asn-lookup.underscoredone.com/lookup
summary: >-
  _done documents NO rate limits and emits NO rate-limit headers. The throttle is economic —
  every call costs $0.01 — so there is no quota to publish, but there is also no runtime signal
  an agent can read to back off, and no documented 429 behaviour.
limit_count: 0
documented: false
headers_returned: []
retry_after: false
status_on_exhaustion: undocumented
observed:
  - probe: 'POST https://asn-lookup.underscoredone.com/lookup'
    http_status: 402
    rate_limit_headers_present: false
    headers_seen: [date, content-type, content-length, payment-required, server, x-railway-request-id, x-hikari-trace, x-railway-edge, cf-cache-status, nel, report-to, cf-ray, alt-svc]
    fetched: '2026-08-11'
input_caps_instead_of_rate_limits:
  note: >-
    Several services cap the SIZE of a single request instead of the RATE of requests. These are
    published in the operation descriptions, not as rate limits.
  caps:
    - service: dns-whois-lookup
      cap: up to 10 domains per call
    - service: domain-availability-checker
      cap: 1-10 domain names per call
    - service: http-status-checker
      cap: up to 10 URLs per call
    - service: dmarc-lookup
      cap: 'bulk — "one or many" domains per call, no stated ceiling'
gaps:
  - No 429 response is declared on any of the 27 operations.
  - No RateLimit-* / X-RateLimit-* / Retry-After header on any observed response.
  - >-
    Because the only backpressure signal would be a 429 that is neither documented nor observed,
    an agent looping over this API has nothing to read but latency.
cross_links:
  plans: plans/done-plans-pricing.yml
  errors: errors/done-problem-types.yml
  conventions: conventions/done-conventions.yml