Add key/value pairs to compose an encoded query string, and paste an existing query string to decode it into readable pairs. Copy the result with one click.
Yes — the builder uses URLSearchParams, which percent-encodes special characters so spaces, ampersands and symbols stay valid.
Yes — repeating a key appends multiple values, matching how servers read array-style parameters like tag=a&tag=b.
The output shows the raw query string; add the ? yourself when joining it to a URL path, or copy the previewed ?-prefixed version.