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Base64 Encoder / Decoder

Encode and decode text to and from Base64. Handles Unicode correctly.

 

What is Base64?

Base64 is a binary-to-text encoding scheme that represents binary data as printable ASCII characters using 64 symbols (A–Z, a–z, 0–9, +, /) plus = for padding. Every 3 input bytes become 4 output characters, expanding size by ~33%. Defined in RFC 4648.

Common uses

  • Email attachments — MIME encodes binary attachments as Base64 so they can travel through text-only email protocols.
  • Data URLs — Embed images/fonts directly in HTML/CSS as data:image/png;base64,… without separate HTTP requests.
  • API payloads — Pass binary data (images, PDFs, keys) through JSON or query strings that only accept text characters.

Privacy

All encoding and decoding runs 100% in your browser. No data is ever sent to a server.