Quick start
- Use Parse query when you have a full URL or a raw query string.
- Use Build query when you have one key=value pair per line.
- Keep private tokens and personal data out of the input when the URL might be shared.
Best uses
These are the situations this tool is meant for. If your task is close to one of these, the examples and notes below can help you choose the right inputs.
- Decode URL parameters while debugging filters, search pages, or app links.
- Group repeated keys so duplicate values are easy to spot.
- Build a correctly encoded query string from plain key-value lines.
- Compare UTM links, search URLs, and app-state URLs before sharing.
What this calculator is solving
The Query String Parser is for reading and building the part of a URL that comes after the question mark. It helps you see filters, campaign values, repeated keys, and app-state values without mentally decoding percent signs and plus signs.
You do not need to memorize the formula first. Start by matching each input label on the calculator to the number, date, unit, or setting you actually have.
The formula in plain language
In plain language: Parse mode extracts the query part and reads it with URLSearchParams. Build mode appends each key-value line with URLSearchParams encoding. The examples on the page are there so you can compare your inputs with a filled-out calculation before copying the answer.
If that sounds abstract, use the example cards on the calculator page. They show a complete set of inputs and the kind of answer you should expect.
How to read the answer
Read the headline result first. Then look at the smaller supporting lines because they explain the parts behind the answer, such as totals, units, ranges, or formula steps.
- Parsed output is shown as readable JSON.
- Built output starts with a question mark and is encoded for use in a URL.
- Duplicate keys tells you when the same parameter appears more than once.
Common mistakes to avoid
If the answer looks strange, the most likely cause is a small input mismatch: the wrong unit, date, weight, scale, mode, or policy assumption.
- Do not assume a query string is secret just because it appears after a question mark.
- Do not hand-convert spaces and special characters when the builder can encode them.
- Check repeated keys because some apps use them intentionally and others ignore later values.
Research and references
These references shaped the calculator assumptions, unit choices, or safety notes.
Examples from the calculator
Decoded JSON with repeated tag values
Readable key-value output
?utm_source=newsletter&utm_medium=email
FAQ in plain language
When should I use the Query String Parser?
Use it when your task matches one of these common needs: Decode URL parameters while debugging filters, search pages, or app links. Group repeated keys so duplicate values are easy to spot. It works best when you already know the values, dates, units, or settings the page asks for.
What is the Query String Parser doing with my inputs?
In plain language: Parse mode extracts the query part and reads it with URLSearchParams. Build mode appends each key-value line with URLSearchParams encoding. The examples on the page are there so you can compare your inputs with a filled-out calculation before copying the answer.
What do the main Query String Parser inputs mean?
The main inputs are the values, text, dates, units, or settings the tool needs before it can work. Read each field label carefully, keep units consistent, and compare your entry with the examples if the answer looks strange.
How should I read the Query String Parser answer?
Read the output next to your original input. If the tool changes format, units, encoding, spacing, or capitalization, compare a small sample before copying the whole result into another app.
What should I double-check before trusting the answer?
Query strings can be logged, shared, or indexed. Do not place passwords, private tokens, or sensitive identifiers in public URLs. Also check that you used the right unit, date, scale, or mode because small input changes can change the result.
Does the site save what I enter?
No. The calculator runs in your browser tab. Your recent answers stay only on the page while you use it, and they are not sent to a server.
Related tools
- UTM Builder Build campaign URLs with source, medium, campaign, content, and term parameters.
- URL Encode / Decode Percent-encode URL component text or decode percent-encoded text.
- JSON Formatter Format and validate JSON with two-space indentation and optional sorted object keys.
Privacy and copying results
Recent answers stay visible only while you work in the current browser tab. They are not sent to a server.
Use Copy answer when you want to paste the expression and result into notes, homework, a message, or another document. Check the units and assumptions before copying.