Query String to JSON Converter (and back)

Convert URL query strings to JSON and JSON back to a query string. Handles repeated keys as arrays, strips leading ? or &, and runs entirely in your browser.

Runs 100% in your browser — nothing is uploaded.

Query string

JSON

{
  "user": "ada",
  "role": [
    "admin",
    "engineer"
  ],
  "active": "true",
  "department": "platform"
}

Frequently asked

How are repeated keys handled?

?a=1&a=2 becomes {"a":["1","2"]}. Values are always strings — the browser's URLSearchParams API does not infer types.

Do I need to include the leading "?"?

No. A leading ? or & is stripped automatically. You can paste an entire URL and the querystring portion will be parsed if it comes after the ?.

Does JSON → query string encode special characters?

Yes — URLSearchParams handles percent-encoding, so spaces become +, and reserved characters are escaped correctly.

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