Query String Builder

Build a URL query string

A query string carries parameters at the end of a URL after a question mark, with each parameter written as a key and value joined by an equals sign and pairs separated by ampersands. Special characters in keys and values must be percent-encoded so the URL stays valid. This builder takes your key-value pairs, one per line, encodes them correctly, and joins them into a query string. Optionally it appends the string to a base URL, adding the question mark or ampersand as needed.

Values containing spaces, ampersands, equals signs and other reserved characters are encoded automatically, so the resulting URL works reliably.

Why correct encoding matters

Manually building query strings is a common source of broken links and bugs, because forgetting to encode a space, ampersand or plus sign changes how the server interprets the parameters. Letting a tool handle the encoding guarantees a valid URL. Developers use query strings for search parameters, filters, pagination, tracking codes and API calls.

The builder encodes using the standard percent-encoding that servers and frameworks expect, matching the behaviour of URL libraries in most languages. Skipping empty values keeps the string tidy when some parameters are optional. All building happens locally in your browser.

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