Why does btoa/atob fail on emoji?

The native APIs assume Latin-1. This tool handles UTF-8 correctly via TextEncoder.

What's URL-safe base64?

It swaps '+' and '/' for '-' and '_', and drops '=' padding — used by JWTs and URL query parameters.

Does Base64 encrypt my data?

No. Base64 is an encoding, not encryption — anyone can decode it instantly without a key. HTTP Basic Auth gets its protection from HTTPS, not from the Base64 wrapper. Encrypt before encoding if the data needs protecting.

When should I use the URL-safe variant?

Whenever the encoded value will appear in a URL, a query parameter, a filename or an HTTP header. Standard Base64 uses + and /, which have special meaning in those contexts; URL-safe Base64 replaces them with - and _.

Why does my decoded output look like garbage?

Because the original bytes were binary — an image, an archive, a compressed blob — rather than text. Those bytes are not valid UTF-8 and render as replacement characters. The decode succeeded; the data simply is not text.

Base64 Encoder & Decoder

Encode and decode Base64 correctly for any Unicode input — emoji, accented characters and non-Latin scripts included. Optional URL-safe alphabet for JWTs and query strings.

Last updated: 2026-07-21 · Runs 100% in your browser

url-safe

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Output

Result will appear here.

// What is the Base64 Encoder?

The Base64 Encoder and Decoder converts text to and from the Base64 alphabet in both directions, with an option for the URL-safe variant. Base64 represents arbitrary bytes using 64 printable ASCII characters, which is how binary data survives channels that were designed for text: email MIME parts, data URIs, HTTP headers and JSON string values. Every three input bytes become four output characters, so encoded data is roughly a third larger than the original. The URL-safe variant swaps + and / for - and _ so the result can sit in a URL or filename without percent-encoding — the encoding JWTs use. Encoding and decoding run in your browser, which is what makes it safe to inspect a real token.