# Translating curl to fetch()

> The browser fetch API and curl describe the same request differently. Method, headers, and body map across cleanly, but a couple of differences (implicit form Content-Type, cookies, and TLS verification) need care.

Source: https://ronutz.com/en/learn/curl-to-fetch  
Updated: 2026-07-01  
Related tools: https://ronutz.com/en/tools/http-request-translator

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`fetch()` and curl express the same request in different shapes, and the mapping is mostly mechanical.

The method becomes the `method` option; GET is the default and can be omitted. Each `-H` header becomes an entry in the `headers` object. The body becomes `body`: a `-d` string goes straight in, but because curl's `-d` implies `application/x-www-form-urlencoded`, fetch needs that Content-Type stated explicitly unless the command set another. A `-F` multipart upload becomes a `FormData` object built up field by field; the browser sets the multipart boundary, so you do not set Content-Type yourself.

Two differences catch people out. First, fetch does not carry cookies by default the way a shell session might; sending them needs `credentials: "include"`. Second, fetch cannot disable TLS certificate verification, so a `-k` command has no faithful browser equivalent.

Everything else is a direct translation from the parsed request, which is why a tool that has already parsed the curl command can generate the fetch call for you.