Base64 Encoder/Decoder

About this tool

Base64 is an encoding scheme that converts binary data into text made of 64 printable ASCII characters (A-Z, a-z, 0-9, +, /). It originated as a solution for transmitting binary data through protocols designed only for text, such as email or older HTTP headers. Today you find it in JWT tokens, where both header and payload are Base64url encoded, in embedded images inside CSS and HTML ("data:image/png;base64,..."), in HTTP Basic Auth, which sends a Base64 encoded "username:password" string, and in MIME email attachments. The encoded output is always about 33% longer than the original. Important: Base64 is encoding, not encryption - anyone can decode it without a password.

How to use

1. 1Choose the mode: Encode (text → Base64) or Decode (Base64 → text) with the Swap button.
2. 2Paste the input text or Base64 string into the input field.
3. 3The result appears instantly in the output field without needing to click generate.
4. 4If the Base64 input is invalid during decoding, an error message with the problem description is displayed.
5. 5Copy the result with the Copy button.

Specifications and limits

UTF-8 text encoding to Base64 and Base64 decoding back to text. Output is approximately 33% longer than input, because every 3 bytes become 4 characters. Browser-side processing - no data is sent to a server. The Swap button switches between encode and decode mode. Invalid Base64 input shows an error message while decoding. Base64 is not encryption - encoded data can be decoded immediately by anyone.