Why Now?

Over the past few months, we've experienced exciting growth. More than 5,000 senders have joined Resend to deliver their critical transactional emails. This growth has moved us toward specific investments in how we handle load on our API.

To that end, we’re announcing API rate limits.

Every customer will have a rate limit of 10 requests per second by default, which should be sufficient for most use cases. As needed, customers can request additional rate limit.

Transparency

We want to give you the proper tools to work well with this new rate limit, so we’ve added new headers in the API response to show the current usage.

These headers were built in conformance with the IETF standard to facilitate adoption:

• ratelimit-limit: Maximum number of requests allowed within a window
• ratelimit-remaining: How many requests you have left within the current window.
• ratelimit-reset: How many seconds until the limits are reset.
• retry-after: How many seconds you should wait before making a follow-up request.

If you exceed your rate limit for that window, you’ll receive a 429 response error code.

To prevent this, we recommend reducing the rate at which you request the API. This can be done by introducing a queue mechanism or reducing the number of concurrent requests per second.

If you want to learn more about how rate limits work, check the API documentation.