Base64 Decoder
Decode Base64 back to text.
Hello, DevKit!
What is a Base64 Decoder?
Decoding reverses Base64: the four-character groups are turned back into the original bytes, which are then interpreted as UTF-8 text. If the original data was not text — an image, a compressed archive — the result will look like noise, because it is bytes rather than characters.
Real-world Base64 is often not in the standard alphabet. Values taken from URLs, filenames or JWTs use - and _ in place of + and /, and frequently have their = padding stripped. This decoder normalises both cases before decoding, so you can paste what you found without cleaning it up first.
When you need it
- A log line, cookie or header contains a Base64 value you need to read.
- You are inspecting a JWT segment by hand.
- A Kubernetes secret or CI variable holds a Base64-encoded value.
- An email source contains a Base64 body part.
- A data URI in CSS or HTML needs checking.
How to use the Base64 Decoder
- Paste the Base64 string into the input panel.
- The decoded text appears immediately — no need to add padding or convert the alphabet yourself.
- If the input is not valid Base64, the panel says so rather than showing partial output.
- Copy the decoded text.
Examples
Base64 Decoder features
Frequently asked questions
Why does my decoded output look like gibberish?
Because the encoded bytes were not text. Base64 can carry any binary data — an image, a key, a compressed file — and rendering those bytes as characters produces noise. The decode succeeded; the content simply is not text.
My string has no = at the end. Will it still decode?
Yes. Padding is restored automatically before decoding, which is what makes unpadded values from URLs and JWTs work unchanged.
Can I decode a JWT with this?
You can decode one segment at a time. To split a token into header, payload and signature and read the claims in one step, use the JWT Decoder.
Why is my input rejected?
Its length or alphabet is wrong — usually a truncated copy-paste, or characters outside the Base64 set that were picked up along with the value.
Is my data uploaded to a server?
No. Every iZZi DevTools tool runs inside your browser using the standard web platform. The data you paste is processed on your own machine and is never transmitted, stored or logged by us.
Do I need an account?
No. Every core tool is free, unlimited and works without signing in. An account only adds conveniences such as saved snippets and history.
Does it work offline?
Once the page has loaded, yes. Because the processing happens in the browser rather than on a server, the tool keeps working if your connection drops.