Base64 Encoder & Decoder — Online Tool for Text & Files
Encode and decode Base64 text or files. Supports standard and URL-safe variants. Free, no signup.
How to use
- 1 Pick Encode or Decode.
- 2 Paste text or upload a file (up to 5MB).
- 3 Toggle URL-safe Base64 if you need a variant compatible with URLs and filenames.
Why use this tool
- Full Unicode support — emoji and CJK characters encode correctly.
- URL-safe variant — replaces + / with - _ and strips padding.
- File-to-Base64 mode for embedding small images / binary in JSON or data URLs.
- Runs in your browser — your data never reaches our servers.
Frequently asked questions
What is URL-safe Base64?
Standard Base64 uses + / = which break in URLs and filenames. URL-safe Base64 (RFC 4648 §5) replaces + with -, / with _, and removes padding =. Used in JWT, OAuth state, and many web APIs.
Can I encode files?
Yes — click "File → Base64" to upload. Max 5MB to keep the browser responsive. For larger files, use a streaming command-line tool.
Is Base64 encryption?
No — Base64 is reversible encoding. Anyone can decode it. Use it only for transport, never for hiding sensitive data.
What is Base64 Encoder & Decoder?
Base64 is a binary-to-text encoding (RFC 4648) that represents arbitrary bytes using 64 printable ASCII characters (A–Z, a–z, 0–9, plus two extras). The standard variant uses `+` and `/`; the URL-safe variant substitutes `-` and `_` so the output can travel through URLs and filenames untouched. A Base64 Encoder converts text or binary files to and from this representation.
Features
Encode & decode
Convert text or files to Base64 and back, with clear errors on malformed input.
Standard & URL-safe
Switch between the RFC 4648 standard alphabet (+, /) and the URL-safe alphabet (-, _) for URLs and filenames.
Text & binary files
Encode UTF-8 text or drop in any binary file (images, PDFs) — output stays byte-accurate.
100% private
Runs entirely client-side — your input is never uploaded, logged, or rate-limited.
Example
Input
Hello, Zerethon!Output
SGVsbG8sIFplcmV0aG9uIQ==Common use cases
-
1
Embed images as data URIs
Base64-encode a small image to inline it in CSS or HTML and save an HTTP request.
-
2
Build a Basic Auth header
Encode "user:password" for the HTTP Authorization header. Note: Base64 is encoding, not encryption — it hides nothing.
-
3
Inspect a JWT
Decode the URL-safe Base64 segments of a JSON Web Token to read its header and claims.
How Base64 Encoder & Decoder compares to alternatives
| Feature | Zerethon Tools | Typical online tools | Desktop apps |
|---|---|---|---|
| Files leave device | No | Yes (upload) | No |
| URL-safe variant | Yes | Sometimes | Yes |
| Binary file support | Yes | Sometimes | Yes |
| Free | Yes | Yes | Often free |
| Signup required | No | Sometimes | No |
Zerethon's Base64 tool encodes and decodes both text and binary files entirely in your browser, following RFC 4648. It supports the standard alphabet (+, /) and the URL-safe alphabet (-, _), encodes UTF-8 text correctly, and never uploads your data. Free, no signup, no rate limits.
- Category
- Developer
- Pricing
- Free
- Privacy
- Browser-based
- Signup
- Not required
References
Privacy
Your data never leaves your browser unless explicitly stated. Base64 Encoder & Decoder runs entirely client-side — no server upload, no logging, no tracking of your input.
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