Query String Builder
Build a correctly encoded query string from parameters, or parse one back.
Runs in your browser. Nothing is uploaded — your input is processed on this device and discarded when you close the tab.
Query String Builder
How to use this tool
- Type one parameter per line as key=value (a key with no = gets an empty value).
- Click Run to get the encoded query string, and the full URL if you gave a base URL.
- Load the sample to see spaces and special characters encoded correctly.
Worked example
Parameters q=hello world and page=2 build the query string q=hello%20world&page=2 — the space becomes %20, and the ampersand stays as the separator, not part of a value.
What this tool does not do / Limits
Duplicate keys are kept as repeated pairs, in the order given, which is how browsers submit repeated form fields. Values are encoded with encodeURIComponent, so a value containing & or = is encoded rather than splitting the string. This tool builds query strings only; it does not fetch the resulting URL.
Frequently asked questions
How are spaces encoded?
As %20, which is the encodeURIComponent form and is accepted everywhere. Some forms use +, which means the same thing in a query string, but %20 is unambiguous.
Can I paste an existing query string to read it?
Paste its pairs as key=value lines instead — the builder re-encodes them cleanly. A raw query string pasted as one line is treated as a single parameter, so split it first.
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