Query String Parser
Paste a URL query string to get a JSON object. Nothing is uploaded - parsing runs in your browser.
How the query string parser works
A query string is the part of a URL after the ?. This tool splits it on & (or ;), decodes each key and value, and hands back a JSON object. A key that repeats - or that is written with a trailing [] - becomes an array, so nothing is silently overwritten. If you paste a string with a broken percent escape, the output names the exact character position of the problem. When you need tidy output, formalise it with the JSON formatter, or check how characters are encoded with the HTML entity decoder.
Frequently asked questions
Is my query string uploaded anywhere?
No. The string is parsed in your browser with built-in JavaScript. Nothing is sent to a server and nothing is stored between visits.
How are repeated keys handled?
A key that appears more than once becomes an array in document order, so a=1&a=2 turns into {"a":["1","2"]} instead of overwriting the first value.
What does the [] suffix do?
A key written as c[]=1&c[]=2 is treated as an array too, so the bracket convention and plain repeated keys produce the same merged result.
Are values percent-decoded?
Yes. Percent escapes such as %20 are decoded and a plus sign is read as a space, which matches how a browser interprets a submitted form.
What happens if the string is malformed?
If a percent escape cannot be decoded, the output box shows an error naming the exact character position, so you can fix the source string instead of guessing.
Can I get compact or indented JSON?
Yes. Pick an indent width for readable output or press Minify to get a single compact line; either way the output is valid JSON text.
Related: open the JSON formatter to tidy the result, decode HTML entities with the HTML entity decoder, sort lines with the line sorter, count words with the word counter, and browse every browser-only tool on the all tools page.