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Base64 Decoder Online

Decode Base64 strings, files, and images online for free. Fast, secure client-side Base64 decoding tool.

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Free Online Base64 Decoder

Decode any Base64-encoded string back to its original text, binary data, or image. This tool runs entirely in your browser -- your data never leaves your device. Supports standard Base64 (RFC 4648), URL-safe Base64, and data URI decoding for images.

Supported Decoding Modes

  • Text Decoding -- Decode Base64 to plain text (UTF-8)
  • File Decoding -- Decode Base64 to binary files with download
  • Image Preview -- Automatically detect and preview Base64 encoded images
  • URL-Safe -- Handles both standard and URL-safe Base64 variants

Frequently Asked Questions

What is Base64 encoding?
Base64 is a binary-to-text encoding scheme that converts binary data into a string of ASCII characters. It uses 64 characters (A-Z, a-z, 0-9, +, /) plus = for padding. It is commonly used to embed images in HTML/CSS, transmit binary data over text protocols like email (MIME), and encode data in URLs and APIs.
How does Base64 decoding work?
Base64 decoding reverses the encoding process. Each Base64 character maps to a 6-bit value. Four Base64 characters decode to three bytes of binary data. The decoder reads 4 characters at a time, converts them to their 6-bit values, concatenates the bits, and splits them into 8-bit bytes.
Is my data safe when using this tool?
Yes, absolutely. All decoding happens locally in your browser using JavaScript. No data is ever sent to any server. You can verify this by disconnecting from the internet and using the tool offline.
Can I decode Base64 images?
Yes. If the Base64 string represents an image (detected via data URI prefix like data:image/png;base64, or by MIME type magic bytes), the tool will automatically show a preview and allow you to download the image file.
What is the difference between Base64 and URL-safe Base64?
Standard Base64 uses + and / characters which have special meaning in URLs. URL-safe Base64 replaces + with - and / with _ to make the encoded string safe for use in URLs and filenames. This tool handles both formats automatically.

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How to Use

  1. Paste your Base64 encoded data into the input box
  2. The decoder processes automatically in real-time
  3. View the decoded text instantly below
  4. Use the copy button to save the result

Common Use Cases

  • Quick decoding without installing software
  • Decoding data on mobile devices
  • Sharing decoded results with team members
  • Learning how Base64 encoding works

Frequently Asked Questions

Is this decoder free to use?
Yes, completely free. No registration, no limits, no hidden fees.
Do I need to install anything?
No. This is a web-based tool that works in any modern browser without installation.
Can I decode on my phone?
Yes. The tool is fully responsive and works on desktop, tablet, and mobile devices.