Query String Parser / Builder
Two modes in one tool: paste a URL or query string to parse its parameters into a table, or add key-value pairs to generate a query string. Copy result as JSON or raw format. All processing runs in your browser.
Parse a URL query string into key and value rows or build a query string from editable parameter pairs. Parsing and building use the browser URLSearchParams API, so encoding and repeated-parameter behavior follow that API.
How to parse or build a query string
- In Parse mode, paste a full URL or only the query parameters.
- Review each decoded key and value in the table.
- Copy the parsed data as JSON or as a simple key=value string when useful.
- In Build mode, add parameter rows, enter keys and values, and copy the generated query string.
How query string parsing and building work
Parse mode takes everything from the first question mark onward when a question mark is present; otherwise it treats the entire input as query parameters. URLSearchParams decodes percent-encoded values and preserves repeated keys as separate rows in the table.
When parsed rows are copied as JSON, repeated keys are assigned into one object and later values overwrite earlier values. Build mode appends every non-empty key to URLSearchParams and prefixes the serialized output with a question mark.
Privacy and limitations
Parsing and building happen locally in the browser. The tool does not fetch the entered URL. Be careful with query strings that contain passwords, access tokens, email addresses, or other sensitive data, because URLs are often copied into logs, history, analytics, or screenshots.
Frequently asked questions
Can I paste a full URL?
Yes. The parser uses the substring beginning with the first question mark.
Are percent-encoded values decoded?
Yes. URLSearchParams performs the normal decoding.
Are repeated keys supported?
They appear as separate rows, but the Copy JSON action keeps only the last value for a repeated key.
Can I build an empty-key parameter?
No. Build mode skips rows whose key is empty.
Does the tool request the URL from the internet?
No. It only parses or constructs query-string text in the browser.