Rewst is a common tool used in MSP's and supported webhook authentication by providing a secret value published under the "x-rewst-secret" key, which is supported by CIPP and other tools to authenticate webhooks. Rewst does not yet support Svix signatures, but this would be a good addition in the meantime to secure webhook endpoints using Rewst's native functions.

See https://docs.rewst.help/documentation/automations/intro-to-triggers/use-cases-and-examples/using-webhook-triggers#set-trigger-parameters.