Base64 Encoder & Decoder

What is Base64?

Base64 is one of those quiet little inventions that holds a huge part of the modern web together, even though most people never see it directly. At its heart, it is just a way of taking raw bytes — anything from a sentence in your language to a photo from your phone — and rewriting them using only 64 safe, printable characters: A–Z, a–z, 0–9, plus a couple of symbols. That sounds simple, but it solves a real problem: many systems on the internet were originally built to carry plain text, and they break or corrupt data the moment you try to push raw binary through them.

Where you actually use Base64

If you are a developer, you have already used Base64 dozens of times this week without thinking about it. Every time a website embeds a tiny logo directly inside its CSS using a data: URL, that image is Base64 encoded. When your app sends an authentication header, the username and password are bundled together and Base64 encoded before being attached to the request. JSON Web Tokens, the credentials behind most modern logins, are three Base64 chunks separated by dots. Email attachments, SVG icons stored in HTML, small images in chat apps, API payloads carrying file uploads — all of them rely on Base64 to move bytes safely across systems that prefer plain text.

How it works in plain English

The idea is straightforward. Base64 reads your input three bytes at a time, that is 24 bits, and slices those 24 bits into four equal groups of 6 bits each. Six bits can represent any number between 0 and 63, and that is exactly why the alphabet has 64 characters — one for every possible value. If your input does not divide evenly into groups of three bytes, Base64 pads the result with = signs at the end so that decoders know where the original data stopped. That is why Base64 output is always slightly longer than the input — about 33% bigger — but it is also why it is completely reversible without losing a single byte.

Encoding is not encryption

This is the part many beginners get wrong. Base64 is not a security feature. It hides nothing. Anyone with a free decoder — including this page — can turn your encoded text back into the original in milliseconds. Never use it to "protect" passwords, API keys or private messages. If you need real protection, you need encryption with a secret key, such as AES or modern TLS. Use Base64 for what it was designed for: making binary data survive a journey through text-only channels.

How to use this tool

Switch to the Encode tab to paste any text — even with emoji or non-English characters — and convert it into Base64. Switch to Decode to paste a Base64 string and instantly read it back. Everything happens inside your browser; nothing is uploaded, logged or stored. That makes it safe for quick checks of debug payloads, JWT contents or short configuration strings without worrying about leaking sensitive information to a third-party server.