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Text ↔ Base64

Encode UTF-8 text to Base64 and back. URL-safe mode included.

Base64 result
aGVsbG8g7JWI64WVIPCfjLg=

Everything happens in your browser. Nothing is uploaded.

When to use it

Embedding binary in text, stashing API tokens in URLs, or hand-crafting a Basic auth header. Base64 is the standard way to carry bytes that aren't safe as plain ASCII.

How it works

Pick a direction at the top (Encode or Decode), paste into the left pane, and the result appears on the right live. ↔ Swap sends the current result back as the next input.

URL-safe option

+ and / collide with URL syntax, so embedding Base64 directly in a query string breaks. The URL-safe toggle swaps them for - and _ and strips trailing = padding — the flavor used by JWT, OAuth state parameters, and slug-safe filenames.

Common gotchas

  • Unicode / emoji — this tool routes text through a UTF-8 encoder first, so Korean, emoji, and other non-ASCII characters encode cleanly. Calling btoa() directly on them would throw InvalidCharacterError.
  • "atob failed" — whitespace and newlines are tolerated, but any character outside A-Z a-z 0-9 + / = (or - _ in URL-safe mode) is rejected.

Where does your input go?

Encoding and decoding run in your browser. Your text and bytes are never sent or stored. Close the tab and they're gone.

Frequently asked questions

Is Base64 encryption?
No. Base64 is encoding, not encryption — anyone can decode it. It's a way to safely carry binary data through ASCII-only channels. If you need secrecy, layer real encryption (e.g., AES) on top.
Does this handle Unicode and emoji?
Yes. The tool routes input through a UTF-8 encoder before Base64-ing, so Korean, Chinese, Japanese, and emoji all encode correctly. Calling the browser's `btoa()` directly throws InvalidCharacterError on those — this tool sidesteps that.
What's the difference between Base64 and Base64URL?
Standard Base64 uses `+`, `/`, and `=`. Base64URL replaces `+` → `-`, `/` → `_`, and strips `=` padding so the output is safe in URLs. JWT, OAuth state, and slug-friendly filenames all use Base64URL. Toggle URL-safe to switch.
Why does decoding fail?
Base64 only allows A–Z, a–z, 0–9, `+`, `/`, `=` (or `-`, `_` in URL-safe mode). Any other character or a length not divisible by 4 will fail. Whitespace and newlines are tolerated.
Is Base64 case-sensitive?
Yes. Base64 is case-sensitive — `A` and `a` represent different values. You must preserve exact casing when decoding.