Base64 is encoding, not encryption. Anyone with the string can decode it back to the original content.
Hello -> SGVsbG8=Base64 converts binary bytes into text made from common ASCII characters, which makes it convenient for JSON, HTML, CSS, configs, and API fields.
Why Does Base64 Get Larger?
Base64 encodes about every 3 bytes into 4 characters, so the result is usually about one third larger than the original binary data.
Data URL vs Raw Base64
| Form | Example | Use case |
|---|---|---|
| Raw Base64 | iVBORw0KGgo... | Only the encoded content |
| Data URL | data:image/png;base64,iVBOR... | Includes MIME type and can be used as img src |
| URL Safe Base64 | Uses - and _ | Common in JWT and URL contexts |
Common Pitfalls
- Treating Base64 as encryption and exposing sensitive data.
- Missing trailing padding characters when copying.
- Sending a Data URL when the backend expects raw Base64.
- Embedding very large images as Base64 and slowing down pages or APIs.
- Mixing standard Base64 and URL Safe Base64.