URL Encoding: What Those %20 Signs Mean and When to Use Them
Spaces become %20, ampersands become %26, and suddenly your URL works. A practical guide to URL encoding for anyone who's ever copied a link that broke.
You copy a link from an email. It has spaces and Chinese characters in it. You paste it into a browser and it is broken — half the characters turned into gibberish. That is because URLs can only contain a limited set of characters. Everything else needs to be encoded.
An online URL encoder does this in one click. Paste your URL, and it converts all the special characters into percent-encoded format that browsers and servers understand.
What gets encoded and why
URLs can only safely contain: letters (A-Z, a-z), numbers (0-9), hyphens, underscores, periods, and tildes. Everything else — spaces, symbols, non-Latin characters — gets converted to a percent sign followed by two hex digits.
Space becomes %20. Ampersand (&) becomes %26. A Chinese character like 中文 becomes %E4%B8%AD%E6%96%87. The browser automatically decodes these back to readable text in the address bar, which is why you see the Chinese characters but the actual URL underneath is encoded.
Characters that always need encoding: space (%20), hash (%23), percent (%25), ampersand (%26), plus (%2B), question mark when not starting a query string, and any byte above 0x7F (all non-ASCII characters).
Common URL encoding mistakes
Double encoding. You encode a URL, then encode it again. %20 becomes %2520 (the % gets encoded to %25). The browser decodes once and you are left with %20 instead of a space. This happens most often when URL encoding is applied at multiple layers — your code encodes, then the framework encodes again.
Encoding the entire URL vs just the query string. You should encode the query parameter values, not the whole URL. https://example.com/search?q=hello%20world is correct. Encoding the entire thing breaks the structure.
Forgetting to decode before displaying. If you show a percent-encoded string to users as-is, it looks broken. Always decode before display. Our URL decoder handles both directions — paste encoded text to see the original.
When you need to manually encode
You need to manually encode URLs when building query strings, working with APIs, or creating links that contain user-generated content. If your URL includes a search term, a username, or any text with special characters, encode it first.
Most programming languages have built-in functions: encodeURIComponent() in JavaScript, urllib.parse.quote() in Python, URLEncoder.encode() in Java. But if you need a quick check without writing code, the online encoder is right there.
Tools mentioned in this article
URL Encoder/Decoder
Encode special characters in URLs and decode percent-encoded strings back to normal text. Handles full URLs or individual components. Essential for working with query parameters and form data.
Text to Slug
Turn any text into a clean URL slug. Strips special characters, replaces spaces with hyphens, converts to lowercase. Handles accented characters and Unicode — just paste your title and copy the slug.
Base64 Encoder/Decoder
Encode text to Base64 and decode Base64 back to readable text. Works with standard Base64 and URL-safe variants. Quick way to embed data in URLs or decode API responses.