Input
plain text
Chars: 0
Bytes: 0
Output
base64
Chars: 0
Size ratio: —
Drop any file here
or click to browse — converted to Base64 in-browser
Drop an image here
PNG, JPG, GIF, WebP, SVG → Base64 data URL for CSS/HTML
What is URL-safe Base64? Standard Base64 uses
+, / and = which break URLs. URL-safe Base64 (RFC 4648) replaces them with -, _ and no padding. Used in JWT tokens, OAuth, file names.
Plain Text
URL-Safe Base64
Character mapping
+ (standard)- (safe)
/ (standard)_ (safe)
= (padding)omitted
Convert between formats
Standard Base64
⇄
URL-Safe Base64
What is Base64?
Base64 is an encoding scheme that converts binary data to ASCII text using 64 printable characters (A-Z, a-z, 0-9, +, /). It's used to safely transmit binary data over text-only channels like email, HTML attributes, or JSON.
Common uses
- 📧 Email attachments — MIME encoding
- 🔐 JWT tokens — header and payload are URL-safe Base64
- 🖼 Data URLs — embed images directly in HTML/CSS
- 🔑 API keys — Basic Auth encodes user:pass in Base64
- 📦 Binary in JSON — store binary blobs in JSON fields
Size overhead
Base64 encoding increases size by approximately 33% — every 3 bytes of input become 4 characters of output. Padding with = aligns to 4-char blocks.
Base64 alphabet
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/