Encoding

Punycode encode/decode

Encode internationalized domain names (IDN) with unicode characters into ASCII-compatible Punycode (xn--) and back.

Frequently asked questions

What is Punycode used for?

Punycode encodes internationalized domain names containing non-ASCII characters (like münchen.de) into an ASCII-compatible form prefixed with xn--, since the DNS system only supports ASCII labels.

Why should I be careful with Punycode domains?

Punycode enables homograph attacks, where lookalike characters from other alphabets are used to register domains that look identical to a trusted one. If a domain shows an xn-- prefix, decode it here to see what it actually spells out.

Does this only work on full domain names?

You can encode or decode a single label or a full dotted domain — each label between dots is converted independently, with the xn-- prefix only added to labels that actually contain non-ASCII characters.

Similar tools

Base64

Base64 encode and decode — text and files, right in your browser.

Base32

Base32 (RFC 4648) encode and decode — text and files, right in your browser.

URL Encode/Decode

Encode and decode URLs — characters that need escaping in links and query parameters.

HTML Entities Encode/Decode

Encode and decode HTML entities — safely display special characters on a page.

JWT Encoder/Decoder

Encode and decode JWT tokens — header, payload, HMAC signing, and standard claims.

Unicode Escape

Encode and decode Unicode escape sequences — characters as \uXXXX and back.

Other tools

UUID Generator

Generate UUID versions 1, 3, 4, 5, 6 and 7 — random, time-based, and name-based.

Email Header Analyzer

Parse raw email headers (View Source / Show Original) — key fields, the Received chain with hop timings, SPF/DKIM/DMARC, From/Reply-To spoofing indicators.

CSS Minify / Beautify

Compress CSS for production, or format minified CSS into a readable layout.

JSON ↔ YAML / CSV / XML / TOML

Convert JSON to YAML, CSV, XML, or TOML and back — entirely in the browser, no libraries.

CORS Checker / Explainer

Explain step by step whether the browser will allow a cross-origin request — simple/preflight classification, Access-Control-* response header checks, and a verdict.

Credit Card Validator

Validate a card number with the Luhn algorithm, detect the payment network and length. Everything runs in the browser — the number is never sent anywhere.