Useful Utilities

Base64 Converter

Encode text to Base64 or decode it back, with a strict decoder that rejects bad characters, broken padding and non-canonical endings.

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Text or Base64*
DirectionDefault Text to Base64

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About Base64 Converter

Base64 re-encodes bytes so they survive channels that only accept plain text: email bodies, URL parameters, config files and data URLs. This converter works on the raw bytes of your text, so accents, emoji and CJK all survive a round trip.

Encoding produces the standard alphabet with padding and, next to it, the Base64url variant that drops padding and swaps the two URL-hostile characters. Decoding is strict: characters the standard never produces, inconsistent padding, a final group whose leftover bits are not zero, and bytes that are not valid UTF-8 are all rejected with a clear message instead of being quietly repaired.

Questions about Base64 Converter

Why does Base64 make text bigger?

Every three bytes become four characters, so plain ASCII grows by a third. Multi-byte UTF-8 characters grow from their byte count, not their character count.

What is Base64url?

A variant of the same encoding that replaces + and / with - and _ and usually omits padding, so values fit inside URLs and file names. Every encode here shows both forms.

Is Base64 a way to keep secrets?

No. It is an encoding, not encryption: one glance decodes it back. Never store a password or a token as plain Base64 hoping it looks opaque.

Why does my decode fail?

Standard Base64 only uses A-Z, a-z, 0-9, +, / and trailing =. Anything else, or a final group whose leftover bits are non-zero, cannot be a faithful encoding, and this page says so rather than guessing.

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