How does the FormData to JSON converter handle array brackets?

Keys using bracket notation such as tags[] or user[email] are recursively parsed into corresponding native JSON arrays and nested sub-objects.

Can I paste raw multipart/form-data strings from Chrome DevTools?

Yes. The converter extracts boundaries and Content-Disposition headers to pull out field names and values into a clean JSON structure.

Is this conversion safe for sensitive form credentials?

Yes. All parsing executes purely client-side within your browser runtime without sending data over any network.

FormData to JSON Converter: URL-Encoded & Multipart to JSON Online

Seamlessly Modernize Legacy Web Forms to JSON Payloads

Traditional HTML form submissions post data as application/x-www-form-urlencoded or multipart/form-data. When transitioning legacy endpoints to modern REST APIs or GraphQL mutations, developers need a reliable utility to inspect and parse incoming form parameter strings into clean JSON models.

Supported Input Formats

URL-Encoded Strings: Standard HTTP POST body format (e.g. title=My+Post&author=Alex&tags%5B%5D=tech&tags%5B%5D=dev).
Query Parameter Strings: URL query parameters with or without leading question mark (?utm_source=google&page=2).
HTML <form> Markup: Paste raw HTML forms; the parser extracts input name and value attributes automatically.
Multipart Form-Data: Parses boundary delimiters, headers, and fields.

Frequently Asked Questions

How does JavaScript natively convert FormData to JSON?

In modern JavaScript, you can convert a form element to JSON via: Object.fromEntries(new FormData(formElement)). For multi-value fields or nested bracket notations, additional parsing is required, which this tool performs automatically.

Does it decode percent-encoded characters like %20 or %40?

Yes, standard URL percent-encoding (such as spaces into %20 or +, and symbols into %XX hex codes) is accurately decoded using decodeURIComponent().