Base64 Encoder/Decoder
Encode and decode Base64 strings, files, and images. All processing happens locally in your browser.
Understanding Base64
What is Base64?
Base64 is a binary-to-text encoding scheme that represents binary data using 64 ASCII characters. It converts binary data into a format that can be safely transmitted over text-based protocols.
Base64 Alphabet
A-Z (0-25) | a-z (26-51) | 0-9 (52-61) | + (62) | / (63)URL-safe variant uses - and _ instead of + and /
How It Works
Base64 encoding converts every 3 bytes (24 bits) of binary data into 4 ASCII characters (6 bits each). This means encoded data is always about 33% larger than the original.
Man(3 bytes)01001101 01100001 01101110TWFu(4 characters)Common Use Cases
- Data URIs: Embedding images directly in HTML/CSS
- Email Attachments: MIME encoding for binary files
- JSON/XML: Transmitting binary data in text-based formats
- JWT Tokens: URL-safe encoding for authentication tokens
- Certificates: PEM format for SSL/TLS certificates
- APIs: Sending binary data through REST endpoints
Padding with "="
Since Base64 encodes 3 bytes at a time, padding is needed when the input length isn't divisible by 3:
- 1 byte input: 2 characters +
== - 2 bytes input: 3 characters +
= - 3 bytes input: 4 characters (no padding)
URL-safe Base64 often omits padding since the length can be calculated.
Size Increase
Base64 encoding increases data size by approximately 33-37%:
Consider this overhead when embedding large files.
Security Warning
Base64 is NOT encryption! It's simply a different representation of the same data. Anyone can decode Base64 instantly.
- Never use Base64 to "hide" passwords
- Never assume Base64 data is secure
- Never transmit sensitive data in Base64 over insecure channels
For actual security, use proper encryption (AES, RSA) or secure hashing (bcrypt, Argon2).