Base64 Encoder / Decoder
Encode text to Base64 or decode Base64 strings back to plain text.
Plain text
What is Base64?
Base64 converts binary data to ASCII text using 64 characters. It was designed to safely transmit binary over text-only channels. Output is ~33% larger than input.
- 3 bytes input → 4 Base64 chars
- Uses: email (MIME), data URLs, JWT
- Base64 is encoding, NOT encryption
- Base64Url replaces + with - and / with _
What this tool does
Encodes plain text to Base64 format or decodes Base64 strings back to plain text. Base64 is used to safely transmit binary data or special characters over systems that only handle ASCII text.
Input fields explained
Mode
Encode: converts plain text to Base64. Decode: converts Base64 back to plain text. Invalid Base64 will show an error.
Text area
In Encode mode, enter your plain text. In Decode mode, paste a Base64 string (uses characters A–Z, a–z, 0–9, +, / and = padding).
💡 Tips & context
→Base64 increases data size by ~33%. A 3-byte input becomes 4 Base64 characters.
→Common uses: embedding images in HTML as data URIs, encoding email attachments, storing binary data in JSON.
Formula / How it works
3 bytes input → 4 Base64 characters. Output ~33% larger than input.