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Base64 Encoder / Decoder
Encode and decode Base64 and Base64URL (RFC 4648) — UTF-8 text or raw hex bytes, with or without padding and MIME/PEM line breaks. Useful for API payloads, certificate data and JWT inspection.
Follows RFC 4648§4 Base64, §5 Base64URL·verified Oct 2026· double-checked Oct 2026— RFC 4648 §10 vectors; padding, MIME/PEM and error cases match coreutils base64 / basenc on 21,500 cases
How this tool reads Base64
- Alphabets (RFC 4648): standard Base64 (§4) uses
+and/; Base64URL (§5) uses-and_. The decoder accepts either, but not both in one string. - Padding:
=pads the output to a multiple of 4 characters. It is optional when decoding, but if present it must be complete. JWTs (RFC 7515) use Base64URL without padding. - Line breaks: spaces and line breaks are ignored when decoding, so MIME bodies (76 characters per line, RFC 2045) and PEM blocks (64, RFC 7468) decode as-is — paste only the part between the
-----BEGIN/END-----lines. - Text vs bytes: text is encoded as UTF-8. Decoded data that is not valid UTF-8 (keys, certificates, cryptograms) is shown as hex.
Something wrong or missing? Report a problem— we check reports against the specs and fix them.