Toolpaper

Send multipart form-data with cURL in Ruby

Paste a curl command that sends multipart form-data and get idiomatic Ruby code. We pick the right serialization for net/http and set the correct Content-Type.

Quick answer

To convert a cURL command to Ruby, paste it into the Toolpaper workbench below. It parses the command in your browser and emits idiomatic Ruby code — headers, query string, request body, authentication (Bearer, Basic, API key), and cookies are all wired up automatically. No data is uploaded; conversion is fully client-side.

Prefer a different target? See the full cURL to Ruby reference, or jump to the same guide in JavaScript, Node.js, or Python.

InputcURL command
MethodPOST·Headers0·Body—·Form2 fields· Chars 100
OutputRuby · net/http(stdlib)
require 'net/http'
require 'uri'
require 'json'

uri = URI("https://api.example.com/upload")
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == 'https'

request = Net::HTTP::Post.new(uri.request_uri)

response = http.request(request)
puts response.body
Inspect

Example

A representative curl command for this scenario. Paste your own above to convert an exact match.

curl input
curl -X POST https://api.example.com/upload \
  -F "file=@/path/to/photo.png" \
  -F "caption=Hello"

Implementation notes

  • Content-Type is detected from -H headers first, then inferred from the body shape when the header is missing.
  • Each -F flag becomes a distinct part; file@ paths are surfaced as net/http file handles so the multipart boundary stays valid.
  • Charset directives on Content-Type (e.g. application/json; charset=utf-8) survive the round trip.

Common mistakes

  • Setting Content-Type manually and then also using net/http's helper — you end up with duplicate headers or the wrong one wins.
  • Forgetting @ in -F "file=@upload.png" — without it curl sends the literal string, not the file. The generator flags this.
  • Trusting the browser DevTools "Copy as cURL" to preserve charset — it often drops it. Clean panel restores common defaults.

Common questions

How is multipart form-data encoded in the generated Ruby?
-F flags translate to multipart form-data with proper boundary handling — files={...} in Python, MultipartFormDataContent in C#, MultipartBody.Part in Java/Kotlin.
Does it preserve Content-Type?
Yes. The Content-Type header is honored and matched against the body so serialization stays consistent.
Is anything uploaded?
No. Parsing and generation happen entirely in your browser.

More payload types in Ruby

Ruby hub →

JSON in Ruby

/how-to/send-json-with-curl-in-ruby

form-urlencoded in Ruby

/how-to/send-form-with-curl-in-ruby

XML in Ruby

/how-to/send-xml-with-curl-in-ruby

GraphQL in Ruby

/how-to/send-graphql-with-curl-in-ruby

The same guide in other languages

All guides →

In JavaScript

/how-to/send-multipart-with-curl-in-javascript

In Node.js

/how-to/send-multipart-with-curl-in-node

In Python

/how-to/send-multipart-with-curl-in-python

In Go

/how-to/send-multipart-with-curl-in-go

In PHP

/how-to/send-multipart-with-curl-in-php

In Rust

/how-to/send-multipart-with-curl-in-rust

In Java

/how-to/send-multipart-with-curl-in-java

In Kotlin

/how-to/send-multipart-with-curl-in-kotlin

Full Ruby reference on the cURL to Ruby hub, or open the main converter for all 18 targets.