Query Params ↔ JSON
Convert between URL query strings and JSON objects. Handles arrays and type coercion.
Edit either panel to convert instantly.
true / false → boolean · numbers → number · null → null
Repeated keys (e.g. tags=a&tags=b) become JSON arrays. Arrays serialize back to repeated keys.
About this tool
URL query parameters and JSON represent the same kinds of data in different formats. Query strings (key=value&key2=value2) are the standard for GET request parameters, while JSON is the standard for POST/PUT/PATCH request bodies. Converting between them is a common need when exploring APIs, migrating from one HTTP method to another, or debugging request construction.
The conversion is not always lossless: query string values are always strings, while JSON supports numbers, booleans, null, arrays, and nested objects. A query parameter page=2 is the string '2', which may or may not match a JSON number 2 depending on how the server parses it. Arrays in query strings lack a universal convention — different frameworks use repeated keys (?tag=a&tag=b), bracket notation (?tag[]=a), or comma-separated values (?tag=a,b).
When constructing API requests, this tool helps you quickly build the query string for GET requests or convert an existing query string into a JSON body for a POST request. It also helps when reading API documentation that shows examples in one format and you need to translate them to the other.