Query String ↔ JSON

A URL's query string (the part after ?) is a flat set of key-value pairs, while JSON supports nested structures and data types. This tool converts between the two, including repeated keys and arrays.

How to use it

• Query → JSON: paste a query string (with or without the leading ?) to get a JSON object with decoded parameter values.
• JSON → Query: paste a JSON object to build a query string from it with correctly URL-encoded values.
• Repeated keys (a=1&a=2) are automatically recognized as an array in the JSON output.

Common uses

• Building query parameters from a JSON configuration object for an API request.
• Reading a complex query string with dozens of parameters in a structured, readable form.
• Debugging why a parameter isn't reaching the backend — checking its encoding and structure after conversion.

Things to keep in mind

Every value in a query string is text — "true", "false", or "42" stay strings in the JSON until code explicitly converts them to the right type.

Nested objects and arrays have no single standard query-string notation — different backend frameworks (PHP, Rails, Express) use slightly different syntax (a[b]=1 vs a.b=1).