Base64 Encoder & Decoder

Encode plain text or decode Base64 formatted data seamlessly. 100% private, client-side, and rapid.

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Drag & Drop local file, or click to upload

Supports images, SVG, fonts, text, JSON (Max 2MB)

Plain Text Input 0 characters | 0 bytes
Base64 Output / Input 0 characters | 0 bytes
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Understanding Base64 Encoding Mathematics

Base64 works by taking groups of three 8-bit bytes (24 bits total) and splitting them into four 6-bit chunks. Each 6-bit chunk maps directly to a predefined index of the standard 64-character table:

Index = [0 - 63] → A-Z (0-25), a-z (26-51), 0-9 (52-61), + (62), / (63)

If the final byte sequence contains fewer than 3 bytes, standard padding characters (=) are appended at the end of the output string to ensure correct modular 4-character blocks.

Encoding Walkthrough

Take the letter "C" (ASCII value 67):

  • Binary structure: 01000011 (8 bits)
  • For Base64, we group bits into blocks of 6: 010000 (Value: 16) and 110000 (Value: 48, padded with trailing zeros).
  • Mapping 16 and 48 to the Base64 alphabet yields "Q" and "w".
  • Since we only had 1 byte, we append two padding characters: "Qw==".
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Frequently Asked Questions

Yes. The entire calculation process is completely compiled inside your local browser tab. No requests are dispatched to any third-party external networks, making it secure for private keys, database credentials, or secret variables.

Standard Base64 encoding utilizes + and / characters, which have special meanings in URL queries and path parsing. URL-safe Base64 substitutes + with a minus sign (-) and / with an underscore (_), and typically omits the trailing = padding marks to prevent parameter interference.

No. Base64 is an encoding system, not a compression algorithm. Because it represents 3 bytes of raw binary using 4 characters, it actually increases the data size by approximately 33%, making files larger.