URL Encoding Checker
Broken links often come from bad encoding: a space in a file name, an accented character, a percent sign that is not followed by two digits, a value encoded twice, or a whole URL pasted into a parameter without encoding. Paste a URL and the checker lists every such problem and shows a correctly encoded version and a readable decoded version.
- Runs in your browser
- No sign-up
- Free to use
How to use URL Encoding Checker
- Paste the URL exactly as you have it.
- Read the list of problems found.
- Copy the correctly encoded version for use in code or configuration.
- Use the decoded version to check that the values are what you intended.
URL Encoding Checker features
Spaces and Unicode
Finds characters that must be percent-encoded.
Invalid sequences
Spots % not followed by two hex digits.
Double encoding
Recognises %25XX patterns.
Nested URLs
Flags unencoded URLs inside query parameters.
Forbidden characters
Lists < > " { } | \ ^ ` and extra # signs.
Fixed versions
Correctly encoded and decoded output side by side.
When to use URL Encoding Checker
- Fixing links to files with spaces or accents.
- Debugging redirect parameters that arrive garbled.
- Checking URLs before putting them in sitemaps or e-mails.
- Understanding why an API rejects a request URL.
URL Encoding Checker FAQ
What is percent-encoding?
Writing a byte as % followed by two hexadecimal digits. Characters outside the safe set, such as spaces (%20) or é (%C3%A9 in UTF-8), are encoded this way.
What is double encoding?
Encoding a value that is already encoded, so % becomes %25. “%3A” turns into “%253A”, and the server receives the literal text “%3A” instead of a colon.
Do browsers not handle spaces themselves?
Browsers fix many problems when you type a URL, but servers, APIs, e-mail clients and sitemaps often do not. URLs in code and files should be encoded properly.
Why encode a URL inside a parameter?
Its own ?, & and # would otherwise be read as part of the outer URL, cutting the value short.
Is upper- or lower-case %3a correct?
Both work. The normalised form is upper case.
Is anything sent?
No.
Why URLs break
URLs are limited to a small set of ASCII characters. Everything else, spaces, accented letters, symbols with special meaning, has to be percent-encoded. When encoding is missing, wrong or applied twice, links fail in ways that are hard to see because the URL looks almost right.
Missing encoding is the most common problem: a file uploaded as “annual report.pdf” or a product name with an accent. Some software encodes such characters automatically, some truncates the URL at the first space, and some rejects it. Encoding them correctly removes the uncertainty.
Double encoding is the opposite mistake, typically when code encodes a value that a library encodes again. The receiving server decodes once and sees the encoded form as literal text. Recognising %25 followed by hex digits is the quickest way to spot it.
Nested URLs, for example a return address in a login link, need their own full encoding, otherwise their ? and & characters are read as part of the outer URL. The checker flags any unencoded URL inside a query string for this reason.