`app.addContentTypeParser()`

Registers a parser for a custom or raw request content type.

Since Fastify 5 Spec ↗

Syntax

app.addContentTypeParser(type, options, parser)

Parameters

Name	Type	Required	Description
`type`	`string \| RegExp \| string[]`	No	The content type(s) to handle.
`options`	`object`	No	Options like { parseAs: "buffer" \| "string" }.
`parser`	`Function`	No	Function producing the parsed body.

Returns

FastifyInstance — The instance, for chaining.

Examples

import Fastify from 'fastify';

const app = Fastify();

app.addContentTypeParser(
  'application/csv',
  { parseAs: 'string' },
  (_req, body, done) => {
    done(null, String(body).trim().split('\n'));
  },
);

Notes

Fastify ships JSON and url-encoded parsers. Use this to handle custom media types or to capture the raw buffer (parseAs: 'buffer') for webhook signature verification.