# Compat signatures

Published 21 September 2026 · Outpost

Change webhook signature schemes without breaking receivers

Outpost can now send a second signature in your previous format alongside the primary one. Receivers keep verifying the old headers and switch to the new scheme on their own schedule.

Use it when you're moving to Outpost from a webhook system you built yourself or from another provider, or when you're changing the signature scheme of a running deployment. Set `DESTINATIONS_WEBHOOK_COMPAT_SIGNATURE_HEADER_NAME` to enable it, and configure the content template, encoding, algorithm and extra headers with the other `DESTINATIONS_WEBHOOK_COMPAT_*` variables. Both signatures use the same destination secret, so receivers keep their existing secret. Nothing changes until the header name is set.

The compat signature also works in Standard Webhooks mode. See the [change webhook signature scheme guide](https://hookdeck.com/docs/outpost/guides/change-webhook-signature-scheme). It's available now in `v1.4.0`.