---
title: Why the raw body matters
description: Every signature scheme signs the exact bytes on the wire — parse first and verification breaks.
---

Every signature scheme signs the exact bytes on the wire. Parse the body and
re-serialize it and the signature no longer matches, because key order,
whitespace, and unicode escaping all changed. This is the single most common
cause of "verification randomly fails".

```ts
// What the provider signed:
'{"id":"evt_1","amount":1000}'

// What JSON.parse → JSON.stringify gives you back — maybe:
'{"amount":1000,"id":"evt_1"}'
// Same object. Different bytes. Signature check fails.
```

The failure is intermittent by nature: it only shows up when the round-trip
changes the bytes, so it looks like the provider is flaky rather than like a
bug on your side.

## What the SDK does about it

The SDK takes the **request**, not your parsed object, and reads the body once
as bytes. Everything downstream — verification, parsing, your handlers — works
from that single read. In Web-standard runtimes (Next.js App Router, Workers,
Deno, Bun, Hono) there is nothing to configure; `handler.fetch` receives the
untouched `Request`.

## The Express footgun

Express is the one place you have to be careful, because `express.json()`
consumes and re-parses the stream before your route ever runs. Mount the
webhook route *before* any JSON parser, with a raw body:

```ts
import express from 'express'
import { toExpressHandler } from 'webhooks-sdk/express'

// Raw on the webhook path only; JSON everywhere else.
app.post('/webhooks/stripe', express.raw({ type: '*/*' }), toExpressHandler(handler))
app.use(express.json())
```

If you can't reorder middleware, use `captureRawBody` from
`webhooks-sdk/express` — see [Framework adapters](/docs/guides/frameworks).

:::tip[Your handlers still get parsed JSON]
Skipping the JSON parser on the webhook route costs you nothing: the
[event envelope](/docs/concepts/event-envelope) hands your handler the parsed
`payload` along with `raw.text()` and `raw.json()` accessors.
:::