Parsing
?q=red+shoes&size=9&size=10&empty= → {"q": "red shoes", "size": ["9", "10"], "empty": ""}.
Query String Builder and Parser
Turn a query string into JSON, or build one from JSON, with repeated keys as lists.
Runs in your browser — nothing you enter is sent to a server.
How the Query String Builder and Parser works
Query → JSON: paste a query string such as ?q=red+shoes&size=9, or a whole URL, and get a JSON object. Values are decoded the way browsers read form data: + is a space, and a name that appears more than once becomes a list.
JSON → query: paste a JSON object and get a correctly encoded query string. Lists become repeated names; true, false and numbers become text; null becomes an empty value. Nested objects have no standard form in query strings, so they are refused with a suggestion.
Examples
Building
{"q": "red shoes", "size": [9, 10], "sale": true} → ?q=red+shoes&size=9&size=10&sale=true.
Frequently asked questions
Why are numbers strings after parsing?
A query string is text; size=9 and size=09 are different strings. Convert values in your code where you know their types.
How are special characters encoded?
Everything except letters, digits and *-._ is percent-encoded in UTF-8, and spaces become +: é&b becomes %C3%A9%26b.
What about a[b]=1 style names?
PHP and some frameworks read brackets as nesting, but browsers and the URL standard don't. Here the name is kept as written, for example "a[b]": "1".
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