Base64 Encoder / Decoder
Encode text to Base64 or decode Base64 strings — 100% client-side
Quick Reference
Characters
A-Z a-z 0-9
Special
+ / =
Size Increase
~33%
Padding
= or ==
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Base64 Encoder Decoder — Free Online Tool
Instantly encode text to Base64 or decode Base64 strings back to readable text. This tool processes everything client-side in your browser — no data is sent to any server, ensuring complete privacy.
Common Use Cases
- Data URIs — Embed small images directly in HTML/CSS without separate file requests
- JWT Tokens — Decode JSON Web Tokens to inspect their payload
- API Development — Encode credentials for HTTP Basic Authentication headers
- Email (MIME) — Understand encoded email attachments and headers
Frequently Asked Questions
What is Base64 encoding?
Base64 is a binary-to-text encoding scheme that converts binary data into a string of ASCII characters. It's commonly used to embed images in HTML/CSS, encode email attachments (MIME), and transmit data in URLs and APIs.
Is Base64 encryption?
No! Base64 is encoding, not encryption. It does not provide any security — anyone can decode a Base64 string. For security, use proper encryption algorithms like AES or RSA.
Why does Base64 make data ~33% larger?
Base64 uses 64 characters (A-Z, a-z, 0-9, +, /) to represent binary data. Since 6 bits of binary map to each Base64 character (vs 8 bits per byte), the encoded output is approximately 4/3 the size of the original.
Where is Base64 used?
Common uses include: data URIs in CSS/HTML (embedding small images), JWT tokens, email attachments (MIME encoding), API request/response bodies, and storing binary data in JSON or XML.
Does this tool process data on the server?
No! All encoding and decoding happens entirely in your browser using JavaScript. Your data never leaves your device — 100% private and secure.