You’ve got a Base64 string. Now what?
You’re staring at SGVsbG8gV29ybGQ= in an API response and it tells you absolutely nothing. That’s Base64, a way to represent data using 64 safe ASCII characters so it can travel through text-only channels intact. Paste it here, hit decode, and you’ll see Hello World. Simple as that.
Base64 shows up everywhere: API payloads, email headers, Kubernetes secrets, JWT tokens, data URIs in stylesheets. It’s not encryption, it’s encoding. The data isn’t hidden, just transformed into something that won’t break when passed through systems that only handle plain text.
How it works
Paste your encoded string, click decode, read the result. The tool handles Unicode (UTF-8) properly, so international characters and emojis come through fine. If your string starts with something like data:text/plain;base64,, the prefix gets stripped automatically before decoding.
Everything runs in your browser. Your data doesn’t go anywhere.
Where you’ll run into Base64
Kubernetes secrets are probably the most annoying example. Run kubectl get secret my-secret -o yaml and every value is Base64-encoded. You can’t just read your database password, you have to decode it first.
JWT tokens are another common one. The header and payload sections are Base64URL-encoded JSON. Decoding them shows you the claims, expiration, issuer, and whatever else is stuffed in there.
HTTP Basic Auth headers are just username:password encoded in Base64. When you’re debugging auth failures and see Authorization: Basic dXNlcjpwYXNz, decoding that string tells you exactly what credentials were sent.
MIME email bodies, data URIs in CSS, API responses that inline binary data as text, it’s the same story every time. The data is encoded, and you need to see what’s actually in there.
One thing to watch out for
There’s standard Base64 and there’s Base64URL. Standard uses + and / with = padding. Base64URL swaps those for - and _ and usually drops the padding. JWTs use Base64URL. If you’re decoding a JWT segment here, swap - to + and _ to / first, or grab a dedicated JWT decoder.
Need to go the other direction? The Base64 Encoder converts text to Base64. For encoded images specifically, the Base64 Image Decoder renders them visually.
FAQ
Is my data safe?
All decoding happens client-side in JavaScript. Nothing gets sent to a server. It’s safe for API keys, tokens, passwords, whatever you need to inspect.
What about data URIs?
Paste the whole thing, data:text/plain;base64,SGVsbG8=, and the tool strips the prefix automatically before decoding.
Invalid Base64?
You’ll get a clear error message. Usually it’s a padding issue, an illegal character, or a truncated string. Check that the length is a multiple of 4 (or has the right = padding).
Binary data?
This decoder outputs UTF-8 text. If your Base64 represents an image or other binary format, use the Base64 Image Decoder instead, it’ll actually render the image.
Unicode support?
Full UTF-8 support. Emojis, CJK characters, Arabic, Cyrillic, all decode correctly as long as the original encoding was UTF-8 (which it almost always is).