Base64URL to Hex Converter

Hex shows the raw bytes, which is what you actually need when debugging cryptography. A JWT signature, for example, is 32 raw HMAC-SHA256 bytes: comparing two signatures byte-by-byte in hex is exact, while Base64URL hides trailing-bit details. Crypto tooling — openssl, Wireshark, hash dumps, HSM logs — speaks hex, so converting Base64URL to hex lets you diff, grep, and paste values straight into those tools.

The RFC 4648 section 5 alphabet: A–Z, a–z, 0–9, plus "-" (value 62) and "_" (value 63). The dash and underscore replace the "+" and "/" of standard Base64 so the encoded string survives inside URLs, filenames, and query parameters without percent-escaping. Trailing "=" padding may be present or omitted — both are accepted here.

No. Padding is optional in Base64URL: JWTs (RFC 7515) always omit it, while some libraries keep it. This tool accepts input with or without trailing "=" and restores the missing padding internally before decoding, so "aGVsbG8" and "aGVsbG8=" decode to the same 5 bytes.

Those two characters belong to standard Base64, not Base64URL — your string is standard Base64. You can convert it yourself by replacing every "+" with "-" and every "/" with "_" (and stripping trailing "="), or decode it with a standard Base64 decoder such as our base64-url-encode tool, which handles both alphabets.

Take the character count n (ignoring any "=" padding), compute floor(n × 3 / 4), then subtract the number of padding characters. Equivalently, every 4 characters decode to 3 bytes, with the final partial group contributing 1 or 2 bytes. The converter shows the exact byte count for your input under the result.

No. Decoding runs entirely in your browser as client-side JavaScript — the page makes zero network requests after loading (no fetch, no XHR). You can even disconnect from the internet after the page loads and the converter keeps working, which makes it safe for pasting production tokens and keys.

In JavaScript: turn your hex into bytes, build a binary string with String.fromCharCode(...bytes), pass it through btoa(), then replace "+" with "-", "/" with "_", and strip trailing "=". In Python: base64.urlsafe_b64encode(bytes.fromhex("68 65 6c 6c 6f".replace(" ", ""))).decode().rstrip("=").