What Base64 actually does
Base64 encodes binary data (images, files) into text using just 64 characters (A–Z, a–z, 0–9, +, /). It is not encryption — anyone can decode it back. Never use it to hide passwords.
It grows the size by ~33%
Because every 3 bytes (24 bits) become 4 characters, the output is about 1.33× the original. A 30KB icon becomes roughly 40KB of Base64 text. It only pays off for small inline assets; for large files it just adds weight.
The most common use: Data URLs
Embed a small image directly in HTML/CSS with no extra request:
.logo { background: url("data:image/png;base64,iVBORw0KGg..."); }
Saving one HTTP request makes this worthwhile for 1–2KB icons.
Tips
- Check the direction (encode vs decode) first. Garbled output usually means it's reversed.
- For URLs,
+and/can break things — use the URL-safe variant (-,_).
Everything runs in your browser; nothing is uploaded. For the underlying mechanics, see the Base64 encoding & decoding guide.