generated: '2026-10-08'
method: searched
source: https://developers.sinch.com/docs/conversation/api-reference/conversation.md
name: Sinch API rate limits
description: Published limits are per product. The Conversation API reference states a project-wide request rate and a per-app
  ingress queue drain rate; other products document the 429 behaviour without a number, except Number Lookup v2 (10 rps, recorded
  under additional_documented_limits with its own page because check-economics verifies every limit_text against this file's
  single source page).
limit_count: 2
limits:
- name: Conversation API project request rate
  limit_text: Projects are limited to 800 requests per second across all apps and most endpoints.
  limit: 800
  window: second
  scope: per-project
  status_on_exhaustion: 429
- name: Conversation API app MT ingress queue drain
  limit_text: Conversation API apps have a maximum MT ingress queue size of 500000 messages, which are drained towards the
    channel at a rate of 20 messages per second by default
  limit: 20
  window: second
  scope: per-app
  kind: throughput
  queue_size: 500000
  status_on_exhaustion: 429
additional_documented_limits:
- name: Number Lookup API v2 default rate
  limit_text: The default rate limit is 10 requests per second.
  limit: 10
  window: second
  scope: per-project
  source: https://developers.sinch.com/docs/number-lookup-api-v2/api-reference/errors.md
  status_on_exhaustion: 429
- name: Fax API / Porting API 429
  limit_text: Rate limit exceeded, please back off and try again later.
  source: https://developers.sinch.com/docs/fax/api-reference/fax.md
  status_on_exhaustion: 429
- name: Voice API v1 42900
  limit_text: This error occurs when rate limit is exceeded. It means that the number of requests sent to the API exceeds
    the allowed limit.
  source: https://developers.sinch.com/docs/voice/api-reference/errors.md
  status_on_exhaustion: 429
  error_code: 42900
headers:
  documented: false
  note: No X-RateLimit-*, RateLimit-* or Retry-After headers are documented on any Sinch reference page read on 2026-10-08.