Base64 Encoder / Decoder

Base64 encoding converts binary data into a text representation using 64 printable ASCII characters: A-Z (26), a-z (26), 0-9 (10), + and / (2), with = used for padding. The encoding process takes every 3 bytes (24 bits) of input and splits them into 4 groups of 6 bits each. Each 6-bit value maps to one of the 64 characters. This tool handles UTF-8 encoding correctly by first converting the input string to a UTF-8 byte sequence using TextEncoder, then applying Base64 encoding to the resulting bytes. This ensures proper handling of multi-byte characters including CJK characters, emoji, and special symbols that standard btoa() cannot process directly. The decoding process reverses these steps: Base64 characters are converted back to bytes, then decoded as UTF-8 text using TextDecoder. The entire process runs in your browser using the Web Encoding API, with no server communication whatsoever.

1. Select "Encode" to convert text to Base64, or "Decode" to convert Base64 back to text. 2. Paste or type your content in the input area. 3. The result appears instantly in the output area. 4. Click "Copy" to copy the result to your clipboard. 5. The tool supports multi-line text and preserves whitespace formatting. Note: The 2MB input limit ensures smooth browser performance. Base64 encoding increases data size by approximately 33%, so a 1.5MB input will produce a 2MB output.

Data URIs: Embedding images directly in HTML or CSS using the data:image/png;base64,... format eliminates additional HTTP requests. JWT Tokens: JSON Web Tokens use Base64url encoding (a URL-safe variant) for the header and payload sections. Email Attachments: MIME encoding uses Base64 to safely transmit binary attachments through text-based email protocols. API Authentication: HTTP Basic Authentication encodes credentials in Base64 format (username:password). Important: Base64 is NOT encryption. Anyone can decode a Base64 string. Never use it to protect sensitive information like passwords or API keys.