Problem Introduction
Twilio callbacks hit your endpoint, but signature checks fail.
Why It Happens
- •URL mismatch behind proxy
- •Mutated request body/params
- •Wrong auth token
- •Environment drift
Step-by-Step Fix
- 1Validate the exact URL used in signature verification.
- 2Preserve request params/body exactly as received.
- 3Confirm auth token for the active Twilio project.
- 4Use Twilio validator implementation path.
- 5Re-run with controlled callback test.
Common Mistakes
- •Verifying against internal URL instead of public URL
- •Lowercasing canonical inputs
- •Using test token in live env
Debugging Workflow
Canonical URL check -> payload capture -> token verification -> replay callback.
Preventive Best Practices
- •Keep one validation utility for all Twilio routes
- •Track signature failures by endpoint
- •Add regression tests for proxy scenarios
Works with webhooks and other async event systems (including AI callbacks).
Instead of guessing, inspecting the exact payload and headers can help debug faster. Tools like Hookmetry support this workflow.
Try the free webhook testerRelated Documentation