What does this tool do?
XSS Encoder is a free tool that safely escapes text for four different output contexts: HTML entity, JavaScript, URL, and CSS. This browser-based encoder helps web developers and security researchers correctly encode output to defend against cross-site scripting (XSS) vulnerabilities.
How to use it
- Choose the required options or length.
- Generate the secure result.
- Copy and store the result safely.
The right encoding for every context
The same malicious string is interpreted differently depending on where it lands. HTML entity encoding (<, >, ") is right for an HTML body, but a JavaScript string literal needs escapes like \x3C, a URL parameter needs percent-encoding, and a CSS value needs the \00003c form. This tool produces all four context encodings from your input at once, so you can pick the correct output for the exact sink you're writing into. The decode mode reverses HTML entities and URL encoding.
Encoding is not a substitute for validation
Output encoding is a critical layer of XSS defense, but it is not sufficient on its own. This tool helps you safely write user data into an HTML, JS, URL, or CSS context, yet complementary measures such as input validation, a Content Security Policy (CSP), and HttpOnly cookies are still required. Wherever possible, avoid inherently dangerous sinks like inline event handlers (onclick) or javascript: URLs entirely, since no amount of encoding fully secures them.
Frequently asked questions
What is the difference between HTML and JavaScript encoding?
HTML encoding converts characters like < > " & into entities and is safe inside an HTML body. JavaScript encoding instead escapes single/double quotes, backslashes, and <> using sequences like \x3C, which is what you need when data is placed inside a script block.
Why does it encode both & and / for a single character?
Following OWASP guidance, the slash (/) is encoded as / and the ampersand as &. This prevents premature tag closing and misinterpretation of existing entities, making the escaping more robust.
Why does decode mode only support HTML and URL?
JavaScript and CSS escapes are context-sensitive and can be ambiguous, so they cannot be reversed safely. Decode mode therefore offers only the unambiguous HTML entity and URL percent-encoding decoding.
Is XSS Encoder free?
Yes. XSS Encoder and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. XSS Encoder works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.