How to Parse and Build a URL Query String Online

To parse a query string, paste it into the Query String Parser and click Parse: it splits the text into editable key/value rows, and any edits you make are rebuilt into a correctly encoded query string instantly. The whole process runs in your browser, so the parameters you work with — including tokens and IDs — never leave your machine.

A query string is the part of a URL after the ?, a list of key=value pairs joined by &. Reading or editing one by hand is error-prone because of percent-encoding and repeated keys. This guide walks through parsing an existing string, editing it, and building a fresh one from scratch.

What the Query String Parser does

The tool is two-way. Give it a query string and it produces a clean table of rows you can edit; give it rows and it produces a valid, encoded query string. It is powered by the browser's native URLSearchParams, so its decoding and encoding match exactly what real URLs use.

Two behaviors make it reliable. First, repeated keys — the way arrays are usually passed, such as tag=a&tag=b — are kept as separate rows, so nothing collapses or gets lost. Second, on rebuild every value is percent-encoded with standard rules, so spaces, ampersands, and other reserved characters are escaped correctly.

Step by step: parse an existing query string

1. Copy the query string you want to inspect. You can include the leading ? or leave it off — both work.
2. Paste it into the input box on the Query String Parser.
3. Click Parse. The string is split into a table of key/value rows, with percent-encoded characters decoded so each value is human-readable.
4. Scan the rows to find the parameter you care about — a UTM tag, a filter, an API argument.

Step by step: edit and rebuild

1. Change any key or value directly in its row. The rebuilt query string at the bottom updates as you type.
2. Click Add to insert a new row, or remove a row you no longer need.
3. To pass an array, add the same key on multiple rows — for example three id rows become id=1&id=2&id=3.
4. Copy the finished, encoded query string and paste it back into your URL, API client, or code.

Building a query string from scratch

You do not need an input string to start. Begin with an empty table, click Add, and type your keys and values. This is handy when assembling an API request by hand: add each parameter as a row, let the tool encode the values, and copy the result. Because encoding is automatic, you never have to remember that a space becomes %20 or that an ampersand inside a value must be escaped.

Try the Query String Parser — free and 100% in your browser.

FAQ

Do I need to remove the leading question mark before pasting?

No. The parser accepts input with or without a leading ?. It strips it automatically, so you can paste a value copied straight from an address bar.

Will parsing change the order of my parameters?

Rows appear in the order they were read, and rebuilding writes them back in row order. If you rearrange, add, or remove rows, the output reflects that new order.

What happens to an empty value?

A key with no value, like debug=, is preserved as a row with an empty value field, and it rebuilds the same way, so flags that rely on a bare key are kept intact.

Can I use this offline?

Yes. ByteTools is a PWA and the parser runs entirely client-side, so once the page has loaded it keeps working without a connection.

Related free tools

• URL Parser — break a full URL into its scheme, host, path, and query.
• URL Encoder — percent-encode a single value or string.
• URL Decoder — decode percent-encoded text back to plain characters.
• JSON Formatter — pretty-print JSON you build from parameters.

Built by ByteVancer

ByteTools is a free product of ByteVancer, a software and web development studio that builds web apps, SaaS platforms, and custom software. If you need more than a browser tool — an API, an integration, or a full product — explore what ByteVancer can build with you.