Query String Builder
Build query strings from explicit key-value rows with controlled encoding, repeated keys, and array conventions.
Needed only for Full URL output. Existing query text is preserved and new parameters are appended before any #fragment.
Query Parameters
Each enabled row contributes one key/value pair unless comma splitting is deliberately enabled.
Output Options
Output
Query output will appear here.
A query string is data plus a serialization choice
Query syntax allows applications to place non-hierarchical data after ?. The familiar key=value&key=value shape is a convention layered on top of that syntax, so an API must still define what repeated keys, brackets, commas, empty values, and ordering mean for that endpoint.
Percent encoding here is deliberately strict
Percent-encoded mode encodes each key and value as a UTF-8 component and uses %20 for spaces. It also escapes characters such as !, ', (, ), and * so delimiters cannot accidentally become structure. This is intentionally different from URLSearchParams form serialization, which writes spaces as +.
Unencoded mode is for inspection only. If a raw key or value contains &, =, #, or whitespace, the resulting text can be ambiguous or unsuitable as a URL.
Repeated keys and array notation are not one universal standard
Repeating a name is directly representable in URL query parameters, for example tag=api&tag=http. Bracket notation such as tag[]=api and a single comma-separated value are application conventions. Use whichever form the receiving API documents.
Commas are treated as literal text unless the array-separator option is enabled. When it is enabled, every comma becomes a boundary and empty array items are preserved rather than silently discarded.
Existing query text and fragments stay in the right place
Full URL output leaves an existing query string untouched, appends the new rows with &, and inserts them before a #fragment. Sorting applies only to the new rows because reordering an existing query could change application-specific semantics.
Standards and browser references
The WHATWG URL Standard defines URL parsing, query serialization, and URLSearchParams behavior. MDN documents how URLSearchParams.append() preserves repeated names. For the generic URI component model, see RFC 3986.