Flexport Webhooks

When to Use This Skill

• Setting up Flexport webhook handlers
• Debugging Flexport signature verification failures (X-Hub-Signature-256)
• Understanding Flexport Event objects and milestone identifiers
• Handling shipment, shipment leg, container, document, invoice, and purchase order events

Verification (core)

Flexport signs the raw request body with HMAC keyed on your per-endpoint secret token and sends two GitHub/X-Hub-style headers, each a hex digest prefixed with the algorithm:

• X-Hub-Signature-256 — HMAC-SHA256, formatted sha256=<hex> (use this)
• X-Hub-Signature — HMAC-SHA1, formatted sha1=<hex> (legacy, being deprecated)

Verify against the raw UTF-8 body before parsing JSON, and compare timing-safe.