Content-Type Builder
Assemble a valid HTTP Content-Type header value from a media type and parameters, with RFC 9110 token and quoting checks.
This tool handles input and primary processing in your browser and is designed not to send the input to QuickKit’s server.
Header
Notes
How it works
Enter a media type (type/subtype) and any parameters as name/value rows. The output is a header value following RFC 9110 section 8.3 and RFC 2046 (verified 2026-09-02): media-type = type "/" subtype *( ";" parameter ). The type, subtype, and parameter names are lowercased; a parameter value that is not a bare RFC 9110 token is wrapped in a quoted-string with inner " and \ escaped. Duplicate parameter names, malformed names, and values containing raw control characters are rejected. Guidance notes point out, for example, that RFC 8259 defines JSON as UTF-8 so a charset on application/json is ignored, and that multipart/* needs a boundary — these are notes, not automatic changes. This builds a header value only; it does not send a request.