Quick start
- Use Parse query when you have a full URL, a raw query string, or text that starts with a question mark.
- Use Build query when you have one key=value pair per line, such as q=free calculator and page=2.
- Keep private tokens, signed links, email addresses, and personal data out of the input when the URL might be shared or logged.
Best uses
Best when you need to inspect URL parameters, debug filters, compare campaign links, or build a small encoded query string without writing code.
- 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 tool helps with
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.
Match each input label on the tool to a full URL, a raw query string, or one key=value pair per line depending on the mode you choose.
The logic in plain language
In plain language: Parse mode extracts the query part from a full URL, raw query string, or question-mark string, removes hash fragments from raw input, reads the parameters with URLSearchParams, and groups repeated keys as arrays. Build mode reads one key=value line at a time, appends each pair with URLSearchParams, and returns a copy-ready encoded query string. The examples on the page are there so you can compare your inputs with a filled-out example before copying the answer.
Parse mode takes the query part after the question mark, removes any hash fragment, reads the parameters with URLSearchParams, decodes percent-encoded values, and groups repeated keys as arrays. Build mode reads one key=value line at a time and lets URLSearchParams encode spaces, ampersands, and punctuation for a valid URL query string.
How to read the answer
Read the JSON first, then check duplicate keys and the built query string line so you can spot missing filters, repeated values, or an accidental private value before copying the URL.
- Parsed output is shown as readable JSON with decoded values.
- 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, such as tag=url and tag=developer.
- A plus sign in a form-style query value usually means a space after decoding.
Common mistakes to avoid
Query string mistakes usually come from treating a public URL like a private note, overlooking repeated keys, or hand-editing encoded characters until the link means something different.
- 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.
- Do not paste access tokens, session IDs, or signed URLs into a query parser when a harmless sample would answer the same question.
Quick parse example
Say you paste /search?q=free+calculator&tag=url&tag=developer&page=2. The parser shows q as free calculator, tag as two values, and page as 2.
That means the URL is carrying one search phrase, two tag filters, and a second-page state. If a page is showing the wrong results, those three decoded fields are the first things to check.
- There are 4 parameter entries in the raw query string.
- There are 3 parameter names: q, tag, and page.
- The repeated tag key keeps both url and developer instead of hiding one of them.
Build a small API test string
In Build query mode, enter one pair per line: q=free calculator, page=2, tag=url, and tag=developer. The tool returns ?q=free+calculator&page=2&tag=url&tag=developer.
Use that output when a test URL, docs example, or support note needs a clean query string. The builder handles the question mark, ampersands, and encoded space so you do not have to add them by hand.
Why duplicate keys matter
Some systems use repeated keys on purpose. A store page might use color=blue&color=green, while an API might accept tag=url&tag=developer as two filters.
Other systems only read the first value or the last value. The parser cannot know that product rule, but it makes the repeated values obvious so you can check the app, API, or analytics system you are working with.
Can I use this for API test links?
Yes, for harmless sample values. It is useful for checking whether a docs example, curl note, or browser test link is passing the values you meant to send.
Use fake IDs and sample text when possible. Real bearer tokens, signed download URLs, customer IDs, and reset links should stay out of public URLs and out of copied troubleshooting notes.
Useful related checks
After you inspect the query string, nearby URL tools can help you encode one value, build campaign labels, or turn the cleaned URL into a readable slug.
Research and references
These references help check URLSearchParams behavior and the URI syntax rules behind query strings.
Worked examples for Query String Parser
4 parameters, 1 duplicate key, and tag shown as ["free", "calculator"]
3 parameters, name decoded as "Access Free Tools", and empty kept as a blank value
?q=calculator+tools&category=developer+tools&page=1
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 text, code, URL, mode, format, or technical setting the page asks for.
What is the Query String Parser doing with my inputs?
In plain language: Parse mode extracts the query part from a full URL, raw query string, or question-mark string, removes hash fragments from raw input, reads the parameters with URLSearchParams, and groups repeated keys as arrays. Build mode reads one key=value line at a time, appends each pair with URLSearchParams, and returns a copy-ready encoded query string. The examples on the page are there so you can compare your inputs with a filled-out example before copying the answer.
What do the main Query String Parser inputs mean?
Parse query mode: Paste a full URL, a raw query string, or text that starts with a question mark. The tool works on the query part after the question mark. Build query mode: Enter one key=value pair per line. Blank values are allowed when the target app expects an empty parameter. Repeated keys: The parser keeps repeated parameter names visible as arrays in JSON, and build mode lets you repeat the same key on multiple lines. Encoded characters: URLSearchParams decodes query values in parse mode and encodes spaces and special characters when building the output. Private URL data: Treat query strings as shareable URL text, not as a secret place to put tokens, passwords, or customer identifiers.
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 the selected mode, input format, encoding, and whether the text includes private keys, passwords, or sensitive data.
Can I paste a full URL instead of only the query string?
Yes. In parse mode you can paste a full URL such as https://example.com/products?tag=free&page=2, a raw string such as tag=free&page=2, or the same string with a leading question mark. The tool extracts and parses the query part.
How does the parser handle repeated parameters?
Repeated keys stay visible. For tag=free&tag=calculator&page=2, the JSON output shows tag as an array with both values, and the duplicate-key count warns you that the same parameter name appeared more than once.
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.
Keep exploring
If this guide is close but not exact, these links keep you near the same kind of problem.
- Developer Tools Browse the full category for related tools that help with the same job.
- All free tools Search the complete Access Free Tools library by task, category, or tool name.
- All tool and utility guides Find more plain-language examples, logic notes, mistakes, and result explanations.
- Free tool resources Start here when you are not sure which tool page fits.
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 save the inputs and result in notes, homework, a message, or a project list. Check the units, labels, and limits before copying.