Stripe webhook signatures fail if the request body is JSON-parsed before verification

The signature check computes an HMAC over the exact bytes Stripe sent. Any middleware that parses the body and hands the handler a re-serialized string changes key order, whitespace and Unicode escaping, so the HMAC no longer matches. The symptom is a signature verification error whose message reads No signatures found matching the expected signature for payload, on every event, in both test and live mode.

In Express, mount the raw body parser for the JSON content type on the webhook route only, and place it before any global JSON parser. In the Next.js App Router, read the body with await req.text(). In Cloudflare Workers and Hono, use await c.req.text() together with the async constructEventAsync, because the synchronous variant needs Node crypto that workerd does not provide. Confirm by logging whether the body is a Buffer before verification.