Base64 Encoder and Decoder
Encode text to Base64 or decode Base64 back to text, with full Unicode support.
How to use this tool
- Paste or type your text into the box above.
- The result updates as you change the input — there is nothing to submit and nothing to wait for.
- Read the figures in the result panel, or copy the converted text.
- Use Copy or Download if you need the output elsewhere. Nothing was uploaded at any point.
Base64 encodes binary data using 64 safe characters so it survives systems that expect text. It is not encryption — anyone can decode it instantly, so it protects nothing.
Base64 Encoder and Decoder — the specification
| Direction | Encode or decode |
|---|---|
| Character set | A–Z, a–z, 0–9, + / with = padding |
| Unicode | Handled correctly via UTF-8 |
| Size overhead | Roughly 33% larger when encoded |
How it works
This tool runs entirely in your browser. There is no server involved, which means nothing you type or upload is transmitted, stored, or logged — and there are no usage limits, because there is nothing for us to ration.
You can confirm it yourself: open your browser's developer tools, select the Network tab, and use the tool. No request is made.
A worked example
Run against this page’s own code, with the real input and the real output reproduced below.
What went in
business@onlineaitool.com
What came back
| Encoded length | 36 |
|---|---|
| Original bytes | 25 |
| Overhead | 44 |
Everything above happened in the page as the text was typed. Nothing was sent to a server, which is why it works offline once the page has loaded and why there is no limit on how often you use it.
Who needs Base64 Encoder and Decoder
Embedding small images in CSS or HTML, inspecting a JWT payload, decoding an API token, or moving binary data through a text-only channel.
Base64 Encoder and Decoder — frequently asked questions
Is Base64 encryption?
No, and this matters. It is an encoding, fully reversible by anyone with no key. Never use it to protect a password or any sensitive value.
Why does my encoded text look longer?
Base64 represents three bytes as four characters, so output is about 33% larger than the input. That is the cost of being text-safe.
Does it handle emoji and accents?
Yes. Text is converted to UTF-8 bytes before encoding, so all Unicode round-trips correctly — unlike naive implementations that break on non-ASCII.
Does this work offline?
Yes. Once the page has loaded you can disconnect from the internet and it keeps working, because all the processing happens in your browser. That is also the simplest way to confirm nothing is being sent anywhere.
Is there a limit on how much I can paste in?
Nothing we impose. The practical limit is your device’s memory, since the work happens locally. Very large inputs get slower rather than being refused.
Can I use this on a phone?
Yes. The layout adapts to a small screen and everything works the same way.
Related tools
From other categories
Background reading: Text and Developer Tools That Never Upload Your Data
Your file never leaves your device. Open your browser's Network tab while you use this page and you will see no upload — how that works.
Disclaimer. Published requirements change without notice. Confirm against the official source before you submit. Full disclaimer.