Base64 Encoder / Decoder
Encode plain text to Base64 or decode Base64 strings back to readable text.
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How to use this calculator
- 1
Choose Encode or Decode mode.
- 2
Enter your text (for encoding) or Base64 string (for decoding).
- 3
The result appears instantly.
Frequently asked questions
What is Base64 used for?
Base64 encodes binary data as ASCII text so it can be transmitted safely in text-only contexts: email attachments (MIME), data URIs (embedding images in HTML/CSS), API tokens, and basic HTTP authentication credentials.
Why does Base64 increase size?
Base64 represents every 3 bytes of input as 4 ASCII characters, increasing size by ~33%. This is the tradeoff for making binary data text-safe.
Is Base64 encryption?
No. Base64 is encoding, not encryption. Anyone can decode a Base64 string instantly — it provides no security. For security, use proper encryption (AES, RSA, etc.).
Base64 encoding and decoding explained
How Base64 works
Base64 maps every 3 input bytes to 4 output characters from a 64-character alphabet (A-Z, a-z, 0-9, +, /). Padding = characters ensure the output length is always a multiple of 4. This makes the output safe for text-only channels.
Common Base64 uses in web development
Data URIs embed images directly in HTML: `<img src="data:image/png;base64,...">`. JWT tokens are Base64-encoded JSON (header and payload). Basic Auth headers: `Authorization: Basic base64(username:password)`. CSS background images can be inline Base64.
Learn more from an authoritative source:
MDN Web DocsURL Encoder / Decoder
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