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Free URL Encoder / Decoder & Query Builder
A free, private URL encoder, decoder, and query string builder that runs entirely in your browser with zero dependencies. It uses the same standard JavaScript URL APIs your browser already ships, encodeURIComponent and decodeURIComponent for safe percent-encoding, encodeURI and decodeURI for whole-URL escaping that preserves reserved characters, and URL plus URLSearchParams for parsing and rebuilding query strings. Encode mode turns any text into a URL-safe string so spaces, ampersands, question marks, slashes, and unicode are escaped correctly. Decode mode reverses it, with a clear error when a string contains a malformed escape such as a dangling percent sign. A dedicated toggle exposes the classic space ambiguity: plus signs (the application/x-www-form-urlencoded form style) versus %20 (the RFC 3986 style), so you can match exactly what a server or framework expects. Query Builder mode parses an existing URL or bare query string into an editable key and value table, lets you add, edit, reorder by editing, and remove parameters, and rebuilds a correctly encoded URL live as you type. Everything is computed locally with native browser APIs: nothing is uploaded, no account is required, and nothing is logged.
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Encode and decode URLs natively in your browser, no dependencies
This tool turns any text into a URL-safe string and back again using the standard URL functions built into every modern browser. Encoding relies on encodeURIComponent, the JavaScript function designed to escape a single component of a URL so reserved characters such as ampersand, equals, question mark, slash, and spaces do not break the address. Decoding uses its counterpart decodeURIComponent to restore the original text. There is nothing to install, no library to load, and no account to create: open the page and start working.
For whole addresses you can switch to the encodeURI and decodeURI pair, which deliberately preserve the reserved characters that give a URL its structure while still escaping illegal ones like spaces. Choosing the right scope is the most common source of confusion, so the tool exposes it as a simple toggle and explains what each mode does as you hover over it.
The %20 versus + space problem, made explicit
Spaces are the classic URL gotcha because two different conventions exist. RFC 3986 percent-encodes a space as %20, which is valid anywhere in a URL. The older application/x-www-form-urlencoded convention, used when an HTML form is submitted, encodes a space inside the query string as a plus sign. Most servers tolerate both, but some frameworks and signed-URL schemes are strict, and getting it wrong leads to mysterious bugs where a value arrives with a literal + in it.
Instead of hiding this behind a default, the tool gives you a checkbox to switch between %20 and + for both encoding and the Query Builder output. When decoding, it can also treat + as a space the way a form parser would, so you can faithfully round-trip strings that came from a real form submission. This makes it easy to reproduce exactly what your backend expects and to debug encoding mismatches.
Build and parse query strings with URLSearchParams
Query Builder mode uses the native URL and URLSearchParams APIs to do the heavy lifting. Paste a full URL or a bare query string and it parses every key and value into an editable table; duplicate keys are preserved in order, and percent-encoded values are decoded for display. From there you can add new parameters, edit values, and remove the ones you do not want, while the correctly encoded URL rebuilds live beneath the table.
Because the rebuild goes through URLSearchParams, every value is escaped properly without you having to think about it, which avoids the subtle mistakes that come from hand-concatenating query strings. It is ideal for constructing tracking links with UTM parameters, assembling API request URLs during development, or cleaning up a long shared link. And like the rest of the tool, it all runs locally: your URLs never leave your browser, which you can verify in the DevTools Network tab.
How It Works
Pick a mode: Encode to percent-encode text, Decode to reverse it, or Query Builder to parse and rebuild a URL query string.
Paste your text or URL, then choose options like component versus whole-URL scope and whether spaces become + or %20.
Read the result instantly, copy it to your clipboard or download it, and in Query Builder edit the key and value table to rebuild the URL.
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Key Features
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Use Cases
Limitations
- It encodes and decodes text and query strings: it does not fetch, follow, or validate that a URL actually resolves to a live page
- Whole-URL (encodeURI) scope intentionally leaves reserved characters like : / ? & = intact, so use component scope when you need to escape a single value that may itself contain those characters
- Query Builder treats the part after the first ? as the query and the first # as the fragment boundary; deeply nonstandard or doubly-encoded URLs may need a second pass
- Decoding fails by design on malformed input such as a lone % or an incomplete escape, because the underlying decodeURIComponent throws a URIError rather than guessing
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Frequently Asked Questions
Is this URL encoder and decoder free?
Yes, it is completely free with no limits and no signup. You can encode and decode as much text as you want and build as many query strings as you like. There is nothing to install and no account to create. It runs as a single web page using the URL functions already built into your browser, so there are no usage quotas or paywalls.
Is my data sent to a server?
No. Everything is processed entirely on your device inside the browser using the native encodeURIComponent, decodeURIComponent, URL, and URLSearchParams APIs. Your text and URLs are never uploaded, stored, or logged anywhere. You can confirm this by opening the Network tab in your browser DevTools while you use the tool: you will see no request carrying your input.
What is the difference between %20 and + for spaces?
Both represent a space in an encoded URL, but they come from different rules. %20 is the percent-encoding defined by RFC 3986 and is valid anywhere in a URL. The plus sign is the older application/x-www-form-urlencoded convention used by HTML form submissions, where + means a space specifically inside a query string. Many servers accept either, but some frameworks are strict. This tool gives you a toggle so you can produce exactly the form your target expects, and decode either one correctly.
When should I use component scope versus whole-URL scope?
Use component scope (encodeURIComponent) when you are encoding a single piece of data, such as one query value, a search term, or a path segment, because it escapes reserved characters like &, =, ?, and / that would otherwise change the meaning of the URL. Use whole-URL scope (encodeURI) when you have a complete address and only want to escape illegal characters such as spaces while keeping the structure of : // ? & = intact.
Why does decoding sometimes show an error?
Decoding throws an error when the input contains a malformed percent-escape, for example a lone % with no two hex digits after it, or a sequence like %2 that is cut off. The browser decodeURIComponent function raises a URIError in these cases rather than guessing, and the tool surfaces a clear message explaining the problem. Fix the broken escape, or if the string was double-encoded, decode it twice.
How does the Query Builder work?
Paste a full URL or a bare query string and press Parse: the tool uses the native URLSearchParams API to split it into a table of key and value pairs that you can edit. Change any value, add new rows, or remove parameters, and the encoded URL rebuilds live below the table. Values are percent-encoded automatically, duplicate keys are kept in order, and your space-style toggle (%20 or +) is applied to the output.
Does it work offline and on mobile?
Yes. Because all the work is done by APIs built into your browser, no network access is needed once the page has loaded; you can keep encoding, decoding, and building URLs with no connection. The layout is responsive, so it works on phones and tablets as well as desktops, in any modern browser including Chrome, Firefox, Safari, and Edge.