Base64 Encode / Decode
Convert text to and from Base64 — runs in your browser.
Results appear as you type
Everything runs locally in your browser — your input never leaves this page.
About the Base64 Encode / Decode
Base64 Encode / Decode converts text to and from Base64, the encoding scheme used to safely embed binary or special data in text-only contexts like data URIs, email and JSON. Paste plain text to encode it, or paste a Base64 string to decode it back to readable form. Everything runs entirely in your browser, so the data you paste never leaves your machine.
How to use
- Paste your text or Base64 string into the input box.
- Choose whether to encode or decode.
- Read the converted result instantly.
- Copy the output to your clipboard for use elsewhere.
Base64 is an encoding, not encryption — and the padding matters
Base64 exists to move arbitrary bytes through channels that only reliably carry text: email bodies, JSON string fields, HTTP headers, data URIs. It maps every three bytes onto four ASCII characters, which is why the output is always about 33% larger than the input. Anyone can decode it instantly with no key. If you are using it to hide a value, you are not hiding anything.
There are two alphabets, and mixing them up is the most common failure. Standard Base64 uses `+` and `/` for the last two characters; URL-safe Base64 (RFC 4648 §5) swaps them for `-` and `_` so the result survives being placed in a URL path or query string without further escaping. A JWT uses the URL-safe alphabet with padding stripped, which is why pasting a raw JWT segment into a standard decoder sometimes fails.
The trailing `=` characters are padding that brings the output to a multiple of four. Many decoders accept input without it, and some encoders omit it deliberately, so its absence is not corruption. If a decode fails, check the alphabet before you check the padding — a `-` where the decoder expects `+` is the more likely culprit.
Frequently asked questions
- Is Base64 a form of encryption?
- No. Base64 is encoding, not encryption. Anyone can decode it, so it provides no security and should never be used to protect secrets.
- Why does Base64 output look longer than my input?
- Base64 represents every 3 bytes of data with 4 characters, so encoded output is roughly 33 percent larger than the original.
- Is my data sent to a server?
- No. The conversion happens locally in your browser using JavaScript, so nothing you paste is uploaded anywhere.