Base64 Encoder / Decoder

Base64 Explained: What It Is and When to Use It

Base64 represents arbitrary binary data using 64 safe ASCII characters (A–Z, a–z, 0–9, +, /). It was designed for systems that can only handle text — email attachments, JSON payloads, data URLs — and remains everywhere in modern development.

1. Where You'll Meet Base64

• Data URLs: embedding small images directly in HTML/CSS (data:image/png;base64,...).
• HTTP Basic Auth: the Authorization header encodes user:password in Base64.
• JWT tokens: the header and payload sections are Base64URL-encoded JSON.
• Email (MIME): attachments are transferred as Base64 text.

2. Encoding Is Not Encryption

Base64 provides zero secrecy — decoding requires no key. If you need confidentiality, use real encryption (AES, TLS). Base64's job is transport safety, making sure bytes survive systems that expect plain text.

3. The Size Trade-off

Base64 inflates data by about 33% (3 bytes become 4 characters). That's why large files are better transferred as raw binary, and Base64 is reserved for small payloads where text-safety matters more than size.