Understand rate limits and how to increase them when using the isend.ai API.
The isend.ai API uses response headers to indicate your current rate limit status, following the IETF standard:
Header nameDescription
ratelimit-limitMaximum number of requests allowed within a window.
ratelimit-remainingHow many requests you have left within the current window.
ratelimit-resetHow many seconds until the limits are reset.
retry-afterHow many seconds you should wait before making a follow-up request.
The default rate limit is 2 requests per second. Trusted senders may request an increase. If you exceed the rate limit, the API will return a 429 response error. To review these events, filter for status 429 in your isend.ai logs.

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Tips to Avoid Rate Limits

  • Implement a queueing system for API calls.
  • Throttle or stagger requests to prevent bursts.
  • Avoid sending requests concurrently unless necessary.
  • Monitor your usage through headers in API responses.
If you have unique needs or expect higher traffic, contact our support team to request a rate increase.