Base64 Encoding Explained: What It Is and When to Use It

Base64 shows up everywhere in web development — data URIs, API tokens, email attachments — and it's widely misunderstood. Here's what it actually is and when you'll reach for it.

What Base64 does

Base64 converts binary data into a text string using 64 safe characters. The point is moving binary data through systems that only handle text reliably, without corruption. Encode or decode free with the Base64 encoder and Base64 decoder.

It is NOT encryption

Base64 is encoding, not security. Anyone can decode it instantly — it hides nothing. Never use it to "protect" passwords or secrets. It's a transport format, not a lock.

Where you'll use it

Data URIs: embedding a small image in CSS/HTML as data:image/png;base64,... — make one with the image to Base64 converter. API tokens and Basic Auth: credentials are Base64-encoded in headers. JWTs: header and payload are Base64URL — decode with the JWT decoder.

The size trade-off

Base64 makes data about 33% larger. That's why you embed small images as data URIs but never large ones — the bloat outweighs the saved request.

Related tools

Encoded data often means working with JSON, URL encoding and hex conversion — all free.