API 503 Errors

Incident Report for Klaviyo

Resolved

We confirmed that all API activity has been stable since the fix was released. Any requests that returned 503 errors during the outage window will need to be retried. This incident has been resolved.

Posted Apr 26, 2026 - 04:11 EDT

Monitoring

We successfully implemented a fix as of 3:20 AM US/Eastern that restored all API activity. We are continuing to monitor the results.

Posted Apr 26, 2026 - 03:43 EDT

Identified

Starting at approximately 2:27 AM US/Eastern on 04/25/2026, we began experiencing intermittent elevated errors across our APIs. Some customers may experience 503 errors when trying to log into Klaviyo, load certain pages or make API requests. Our Engineering Team has identified the root cause and has implemented mitigations. We'll provide updates as soon as more information is available.

Posted Apr 26, 2026 - 03:24 EDT

This incident affected: Klaviyo API.