Base64 encoder and decoder

Encode text as standard Base64 or decode a Base64 string. This widget is intended for short text values, not uploaded files.

What Base64 does

Base64 represents bytes using letters, digits, +, /, and optional = padding. For example, Man becomes TWFu. It is an encoding, not encryption: anyone can decode it, so it does not protect passwords or confidential data. Base64 usually increases the data size by about one third.

Limits of this widget

The widget uses the browser’s btoa() and atob() functions. Direct encoding is therefore limited to characters whose code points fit in one byte. Text containing characters such as €, 漢, or emoji produces an error unless it is converted to UTF-8 bytes first. Decoded binary bytes may not display as readable text. The widget has no file upload and does not create data URLs.

This tool uses standard Base64. URL-safe Base64 is a separate variant that replaces + and / with - and _, and often omits padding.

Errors, privacy, and storage

Invalid Base64 input produces an error. Processing happens in your browser, but the input and selected action are saved in localStorage and remain after a reload. Clear them after using sensitive data on a shared device.

Related tools

• HTML encoder and decoder
• URL encoder and decoder

Further reading

• IETF: Base-N Encodings

Widget made with staark