generated: '2026-08-13'
method: searched
source: https://docs.kickbox.com/docs/using-the-api
docs: https://docs.kickbox.com/docs/using-the-api#api-limits
limit_count: 2
summary: >-
  Kickbox publishes two concrete, numeric limits on the API Quickstart page: a concurrency ceiling of
  25 in-flight requests per IP and a throughput ceiling of 8,000 requests per clock minute. Exhaustion
  of the concurrency ceiling returns HTTP 429 and the docs state the caller may retry immediately.
limits:
  - id: parallel-requests-per-ip
    scope: per-ip
    type: concurrency
    limit: 25
    window: concurrent
    burst: null
    status_on_exhaustion: 429
    retry_guidance: >-
      "You will receive a 429 error response if there are too many requests in action at once in this
      way, but you can immediately retry." A slot frees as soon as a response is received and the
      socket is closed.
    source: https://docs.kickbox.com/docs/using-the-api
  - id: requests-per-clock-minute
    scope: per-account
    type: throughput
    limit: 8000
    window: 1 clock minute
    burst: null
    status_on_exhaustion: 429
    note: >-
      Documented as a separate limit from the concurrency ceiling. The window is a clock minute, not
      a rolling minute, so the budget resets on the minute boundary.
    source: https://docs.kickbox.com/docs/using-the-api
response_headers:
  standard_ratelimit_headers: false
  note: >-
    Kickbox returns NO RateLimit-*, X-RateLimit-* or Retry-After headers. It documents two custom
    response headers instead, and neither carries a rate-limit budget — an agent cannot read its
    remaining request allowance from a Kickbox response and must track the 25-parallel and
    8,000/minute ceilings client-side. The one runtime signal that is returned is a credit balance,
    which is a billing quantity rather than a rate limit.
  headers:
    - name: X-Kickbox-Balance
      description: Remaining verification credit balance.
      kind: quota-balance
      source: https://docs.kickbox.com/docs/using-the-api
    - name: X-Kickbox-Response-Time
      description: Elapsed time in milliseconds that Kickbox took to process the request.
      kind: timing
      source: https://docs.kickbox.com/docs/using-the-api
error_envelope:
  status: 429
  body: '{"message": "Rate Limit Exceeded", "success": false}'
  note: >-
    The single-verification docs list "Rate Limit Exceeded" as one of the human-readable strings
    returned in `message` when `success` is false.
related:
  quota:
    model: prepaid verification credits
    note: >-
      Separate from rate limiting. Credits are consumed per verification; unknown results are
      refunded. Kickbox recommends enabling auto-recharge so an API integration does not run out.
    docs: https://docs.kickbox.com/docs/enabling-auto-recharge
  spike_detection:
    docs: https://docs.kickbox.com/docs/spike-detection-alerts
    status: beta
    note: >-
      Customer-configurable alerting (not throttling) on verification volume per API key, per minute
      or per hour, intended to surface form abuse. Requires beta access.