Multer vs Busboy vs Formidable in 2026: Node.js File Upload Parsing, Decoded

Fri, 28 Aug 2026 00:00:00 +0000

Here is a fact most Express developers do not know: the multer middleware you use for every file upload is not a parser at all — it is a convenience wrapper around busboy, a lower-level streaming parser. And the library that started this entire ecosystem, formidable, warns in its own README that its most-used versions have been deprecated for years and are “vulnerable to attacks if you are not implementing it properly.” Three libraries, one multipart/form-data problem, and very different trade-offs between convenience, control, and security. This guide compares them with live repository data and real code from the official docs.

Multipart on Pi Stack

Multer vs Busboy vs Formidable in 2026: Node.js File Upload Parsing, Decoded