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Multipart Form-Data Builder
Build exact multipart bytes for an ordered list of UTF-8 text fields.
Pasted JSON text fields, One UTF-8 JSON file
multipart-body.bin, content-type.txt, multipart-report.json
Browser only
Runs locally in your browser. Your files, pasted content and generated output are not uploaded. Reset clears this tool’s working data.
This tool needs JavaScript. If it does not load, refresh the page and try again.
How to use this tool
- Enter the shown fields. A selected file takes precedence over pasted input, including an empty selected file.
- Build multipart body and inspect the complete result.
- Download multipart-body.bin, content-type.txt, multipart-report.json.
Examples
Two fields with the same name remain two ordered parts.
Limitations
- Names use printable ASCII without quotes or backslashes; values are UTF-8 text with their exact admitted delimiters.
- Up to 100 fields, 200 name characters and 65,536 UTF-8 bytes per value. Any value containing -- followed by the boundary refuses.
- The tool downloads bytes only. File parts, binary part uploads and server interoperability are not established.
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