Base64 Encode / Decode
Convert text and files to Base64.
Runs entirely in your browser. Nothing you enter or upload leaves your device.
What the Base64 encoder does
Base64 turns any bytes into plain letters, digits, + and /, so binary data can travel through text-only places such as JSON, email or a data: URL. This tool converts text to Base64 and back, and can also turn a whole file into a Base64 string.
You might need it to read the payload of an API token, decode a block from an email’s source, build a Basic authorisation value, or embed a small icon straight into CSS or HTML so the page makes one less request. Developers also use it to check what an unfamiliar string in a log or config file actually contains.
How to use the Base64 encoder
- Choose Encode or Decode.
- Type or paste into the left box. The result appears on the right as you type.
- Tick URL-safe if the value will go in a URL or a JWT (it uses - and _ and drops the = padding).
- To encode a file, drop it in the lower panel. You get its Base64, with or without a data: prefix.
Tips for reading the output
When decoding, you don’t need to tidy the input first. Spaces and line breaks are ignored, missing = padding is added back, and the URL-safe characters - and _ are read as + and /. If the input has characters Base64 never uses, or a length that can’t be valid, you’ll see a message saying which. The Swap button moves the result into the input and flips the direction, which is a quick way to confirm a value round-trips.
For files, the panel shows the original size next to the size of the Base64 text, so you can judge whether embedding makes sense. A data: URL works well for a small icon. For a large photo it bloats the page, and a normal image file is usually the better choice. Files up to 25 MB can be encoded.
Questions
Is Base64 encryption?
No. Anyone can decode it. It is an encoding for transport, not a way to hide information.
Why is the output longer than the input?
Base64 uses 4 characters for every 3 bytes, so it is about 33% larger.
What happens with emoji and accents?
Text is converted to UTF-8 bytes first, so every character round-trips correctly. If decoded bytes are not valid UTF-8 text, the tool says so and lets you download the raw bytes instead.
Is my data uploaded?
No. Encoding and decoding happen in your browser.
How do I decode the parts of a JWT?
Paste the header or payload section (the text between the dots) into Decode mode and you’ll see its JSON. For a full breakdown with timestamps and claims, the JWT decoder splits all three parts for you.