Instantly decode Base64 encoded strings back to human-readable plain text. No data leaves your browser — 100% private. Perfect for developers debugging JWT tokens, API responses, and encoded data.
Validation Notice: If the input is not a valid Base64 string, the decoder will display a syntax error. Ensure your input conforms to standard RFC 4648 character blocks (A-Z, a-z, 0-9, +, /, and =).
Our Base64 Decoder is designed to be simple and fast. Follow these three steps:
Copy your Base64 encoded string and paste it into the input box on the left side of the tool.
The tool decodes your input instantly. The plain text output appears automatically in the right panel.
Use the copy icon to copy the decoded text, or click "Download .txt" to save it as a file.
Results appear in real-time as you type or paste your Base64 string.
All processing is done client-side. Your data never leaves your device.
Perfect for decoding JWT tokens, API responses, and encoded config files.
Works flawlessly on smartphones and tablets of all sizes.
Decode as many strings as you need — no usage caps, no registration.
No hidden costs, no premium tiers. Free for everyone, forever.
Base64 is a binary-to-text encoding scheme that transforms binary data into a sequence of printable ASCII characters. It is formally defined in RFC 4648 by the Internet Engineering Task Force (IETF) and is one of the most widely used encoding methods on the internet and in software development.
Base64 encoding converts every 3 bytes of binary data into 4 printable ASCII characters from a set of 64 characters (A-Z, a-z, 0-9, +, and /), with = used for padding. This makes binary data safe to transmit through systems that only support text, such as email (SMTP), JSON APIs, and XML documents.
Base64 encoding is used extensively across the web and in software development. Here are the most common scenarios where you will encounter Base64:
Decoding reverses the encoding process. Each group of four Base64 characters is converted back to three bytes of original binary data. Our tool uses the browser's built-in atob() function — a standard JavaScript function available in all modern browsers — to perform this conversion instantly and accurately. The atob() function is part of the HTML Living Standard maintained by WHATWG.
Base64 is a method of converting binary data into plain ASCII text using 64 characters. It's defined in RFC 4648 and is used to safely transmit data through text-based protocols like HTTP, email, and JSON APIs.
Simply paste your Base64 encoded string into the input box on this page. The tool automatically decodes it to readable text. You can then copy or download the result.
Yes, it's 100% free with no usage limits, no registration required, and no hidden fees. Use it unlimited times.
No. All decoding happens directly in your browser using JavaScript's atob() function. Your data never leaves your device.
You can decode JWT tokens, API responses, email MIME attachments, encoded configuration data, data URIs, and any valid Base64 string.
If the input is not a valid Base64 string, or if it represents binary data (like an image or compressed file), the decoded output will appear as unreadable characters.