Query String Builder
Build a properly encoded query string from key-value pairs.
This tool runs entirely in your browser. Your files are never uploaded to a server.
What this builder does
Creates a query string from ordered key-value rows with the browser URLSearchParams API. Keys are trimmed; rows with an empty trimmed key are skipped, while empty values and duplicate keys are retained.
Example and encoding
Rows `tag = red`, `tag = blue`, and `q = summer sale` produce `?tag=red&tag=blue&q=summer+sale`. URLSearchParams applies application/x-www-form-urlencoded rules, including `+` for spaces and percent encoding for reserved or non-ASCII characters. The copy control includes the leading question mark.
Limits
The tool builds only the query component, not a complete URL. It does not merge with an existing query, validate parameter semantics, sort or deduplicate rows, preserve a literal plus as an unencoded plus, or enforce URL-length limits. Removing every row is allowed; add a new row to continue.
Privacy
Construction happens locally and values are not uploaded.
Frequently Asked Questions
- Does it encode special characters automatically?
- Yes, spaces, ampersands, and other reserved characters in your keys or values are automatically percent-encoded using URLSearchParams.
- Can I add the same key twice?
- Yes, duplicate keys are supported — add two rows with the same key and both will appear in the output string, like tag=red&tag=blue.
- How do I use the result?
- Copy the generated string and append it to any URL after a question mark, for example https://example.com/page?your-generated-string.