# Binary & multipart

Published 1 October 2026 · Event Gateway

Delivery of files, images, and form uploads

Event Gateway now accepts binary and `multipart/form-data` request bodies and delivers them to your destination byte for byte. Until now these bodies were decoded as text, which could alter file contents before delivery.

Binary payloads

A request is treated as binary when its `Content-Type` is a byte-oriented format:

* `application/octet-stream`
* `image/*`, `audio/*`, `video/*`
* Archives and office documents, such as zip and PDF
* `application/protobuf`, `application/cbor`, `application/msgpack`

Requests with `Content-Encoding: gzip` or `x-gzip` are passed through as encoded bytes, including gzipped JSON. Event Gateway does not decompress them.

The destination receives the original bytes, `Content-Type`, and `Content-Length`, including on retries and replays. In the dashboard you can preview images and download the original payload. Transformations see `body: null` and can still change headers, path, and query.

Multipart requests

Form submissions and file uploads keep their original bytes too, and their fields are available as a structured object:

* Filters match on fields, for example `body.event`.
* Transformations receive `request.body` as an object of fields, with each file described by `{ filename, content_type, size }`. You can change text fields or remove files, and the files you keep are sent unchanged.
* Dashboard shows the fields, lists attached files with image previews and per-file downloads, and indexes fields for search.

Transformations can't read or modify file contents yet. See the [multipart requests guide](/docs/guides/multipart-requests) for details.

Existing connections

Connections created before October 1, 2026, 18:40 UTC keep the previous string handling for multipart requests, so their transformations and filters keep working. Once one of these connections receives a multipart request, a notice appears on its settings page. To switch, follow the [multipart migration guide](/docs/guides/multipart-binary-migration).