Query String to JSON Converter

When the same key appears more than once (for example tags=a&tags=b), it becomes a JSON array. A key that appears once stays a plain string.

Yes. Everything up to and including the ? is ignored and any #fragment is dropped, so you can paste a complete URL and still get just the query parameters.

Arrays are expanded into repeated keys. A nested object or array of objects is serialized to JSON and percent-encoded as the value, since query strings are flat key-value pairs.

No. The conversion happens entirely in your browser; nothing is uploaded.

Because bracket syntax is a framework convention, not part of the URL standard. PHP, Rails and the qs library each read items[] or user[name] as structure; a plain URL parser sees one literal key. Repeat the same key instead — items=1&items=2 — and it becomes an array here and almost everywhere.

Both decode to a space in a query string, which is why this accepts either and emits the plus form. In a path segment they are not interchangeable: %20 is a space and a plus sign is a literal plus. That difference is a common source of filenames that arrive with a stray plus in the middle.