What This Tool Does
This tool converts a URL query string into structured JSON, or a JSON object back into a query string, in either direction. Paste a query string with or without the leading ?, or paste a JSON object, pick the direction with the mode toggle, and get an instant, live conversion.
How to Parse or Build a Query String
Choose Parse to JSON or JSON to Query with the mode toggle at the top. In parse mode, paste a query string, decoded key/value pairs appear as JSON on the right, with a table view available alongside the raw output. In stringify mode, paste a JSON object and choose how arrays should be serialized before copying the resulting query string.
How Duplicate Keys and Arrays Are Handled
When parsing, a key that appears more than once, like tags=js&tags=ts, is automatically collected into a JSON array rather than overwriting itself. When converting JSON back to a query string, arrays can be serialized four different ways: repeated keys (the URLSearchParams default), PHP/Rails-style brackets, indexed brackets, or a single comma-separated value, chosen from the Arrays option in stringify mode.
Type Coercion and the + as Space Option
Two toggles are available in parse mode. Coerce types converts numeric and boolean-looking values, and the literal string null, into their real JSON types instead of leaving everything as a string. Decode + as space controls whether a literal + character in the query string is decoded to a space, which is the standard behavior for form-encoded query strings but not always desired for query strings built manually.
Common Uses for a Query String Parser
Debugging what parameters an API call or redirect actually sends, turning a captured URL into a JSON payload for a test or mock, and building a correctly encoded query string from a JSON object for an API request are all common reasons to use a query string parser. Use it to parse query string to json as a query string to json converter, or run the reverse as a json to query string converter, url query parameters to json, convert query string online, query string parser online, parse url parameters online, json object to url query string, and url params to json converter, all in the same panel.