JSON to Query String

What this tool converts

This tool takes a flat JSON object and converts it into a URL-encoded query string using the browser's native URLSearchParams — the same encoding logic browsers use for form submissions and fetch requests. Array values are expanded into repeated keys (e.g. {"tag":["a","b"]} becomes tag=a&tag=b), and special characters in keys or values are percent-encoded automatically.

It only accepts a top-level JSON object, not an array or a primitive — nested objects inside values get stringified with String(), which usually isn't what you want, so keep the structure flat before converting.

When to use it

Use it when building a URL by hand for an API request, a webhook test, or a redirect link, and you have the parameters as a JSON object (from a config file, a Postman collection, or code you're debugging) rather than typed out as key=value pairs. It's also handy when constructing analytics or tracking links where you need several UTM parameters encoded correctly, since manual percent-encoding is error-prone for spaces and special characters.

For the reverse direction — pulling a JSON object back out of an existing query string — use the companion Query String to JSON tool.

Example

Input {"q": "rate limiting", "page": 2, "tags": ["api", "backend"]} converts to q=rate+limiting&page=2&tags=api&tags=backend — note the space in "rate limiting" becomes a +, and the tags array produces two separate tags= entries rather than a single comma-joined value.