What does the Base64 Encoder and Decoder do?
The KitLumi Base64 Encoder and Decoder represents text or binary bytes with printable ASCII characters, or reverses that representation. The conversion runs locally and does not provide secrecy or authentication.
How do you encode or decode Base64?
- Select Encode or Decode.
- Type text, paste Base64, or choose a local file. Enable URL-safe alphabet when the target format requires Base64URL.
- Copy the result or download it. Binary decoded output should be downloaded instead of judged from the text preview.
Base64 or Base64URL?
| Encoding | Characters 62 and 63 | Padding | Typical use |
|---|---|---|---|
| Base64 | + and / | = padding | MIME, files, data transport |
| Base64URL | - and _ | Often omitted | URLs, JWT segments |
What output should you expect?
Encoding Hello produces SGVsbG8=. Base64 usually increases binary size by about one third before transport compression because four encoded characters represent three source bytes.
Frequently asked questions about Base64
Does Base64 encrypt data?
No. Base64 is a reversible binary-to-text encoding, not encryption. Anyone with the encoded value can decode it without a key.
Can I encode a file as Base64?
Yes. Open a file in Encode mode to create Base64 locally. This release limits a selected file to 50 MB to reduce browser-memory failures.
What is Base64URL?
Base64URL replaces plus and slash with hyphen and underscore, and commonly omits padding. Enable URL-safe alphabet for JWT segments and URL-safe values.
Why does decoded binary look corrupted?
The output panel previews decoded bytes as UTF-8 text. Download decoded.bin when the source represents an image, archive, or other binary file.
What changed?
Added UTF-8 text conversion, local file encoding, Base64URL mode, validation, clipboard copy, and decoded binary download.