Form Data to JSON Converter

About this calculator

HTML forms and many APIs submit data as application/x-www-form-urlencoded text — key-value pairs joined with &, keys and values separated by =, and special characters percent-encoded (spaces as + or %20). That flat, order-dependent string is easy for browsers to send but awkward to read or reuse compared to structured JSON, especially once repeated keys like item=1&item=2 need to become arrays.

This tool parses a form-urlencoded string, decodes each key and value, and outputs clean, formatted JSON. Backend developers use it to quickly inspect what a form POST body or query string actually contains, and QA engineers and API testers use it when converting a captured request (from browser dev tools or a proxy like Postman) into a JSON payload for a different endpoint or test fixture.