Query string builder
This query string builder converts a JSON object into the key=value&key=value text that goes after the ? in a URL. Developers use it to build API requests and test links without encoding each value by hand.
- Runs in your browser
- Free, no account needed
- Copy or download the result
Result
Example
{"q":"tea & coffee","tag":["data","AI"],"page":2}q=tea+%26+coffee&tag=data&tag=AI&page=2
How to use the query string builder
- Paste a JSON object such as {"q":"tea","page":2} into the JSON object box.
- Set Key order to Keep input order or Sort keys.
- Set Question mark to Without ? or Start with ?.
- Press Run, then copy the query with Copy result or save it with Download.
How it works
Values can be strings, numbers, true, false or null. Null becomes an empty value, like key=.
An array creates one pair per item with the same key, such as tag=data&tag=AI.
Nested objects, and arrays inside arrays, are rejected with an error. So is JSON whose top level is not an object.
Values are form-encoded, so spaces become + and characters like & and = become percent codes.
Sort keys orders keys by character code, so uppercase letters come before lowercase ones. An empty object gives an empty result, even with Start with ?.
Everything runs in your browser. Your input is not uploaded or stored.
Questions and answers
How do I send the same key more than once?
Use an array, for example {"tag":["a","b"]}. The tool writes tag=a&tag=b.
Why are spaces written as + instead of %20?
The tool uses standard form encoding, where + stands for a space. Servers that decode form-style query strings read it as a space.
Can I use nested objects?
No. There is no single standard way to nest values in a query string, so nested objects are rejected. Flatten them into simple keys first.
Is my data uploaded?
No. The query string is built in your browser.