What is Base64 Decoding?
Base64 decoding reverses the encoding process — it converts a Base64 string back to its original binary or text form. Base64 encoded data is commonly found in JSON APIs, HTML data URIs, email attachments, and JWT tokens.
How to Use This Tool
- Select a mode: Text or Image
- Paste your Base64 string into the Input area
- The decoded output appears in the Output area instantly
- Copy or download the result from the Output area
- If the decoded text looks garbled, open Advanced and try a different Charset (e.g. GBK for Simplified Chinese)
Features
- Text Decoding — decode Base64 strings back to readable text
- Image Preview — paste a data-URI or raw Base64 in Image mode to render a preview
- Charset Support — decode with UTF-8, GBK, Shift_JIS, and more
- URL-Safe Base64 — supports RFC 4648 §5 Base64URL format
- Auto-Detect Charset — automatically detect the character encoding of decoded output
- 100% Browser-Based — your data never leaves your device
FAQ
How do I decode a Base64 string?
Paste your Base64 string into the Input field in Text mode. The decoded result appears in the Output field instantly.
Why is my decoded text garbled?
Garbled output usually means the charset used for decoding does not match the original encoding. Open Advanced and try a different Charset — for example GBK for Simplified Chinese or Shift_JIS for Japanese.
How do I decode a Base64 image?
Switch to Image mode and click Paste Base64 to paste your Base64 string. The tool will render a live image preview if the data is a valid image data URI.
What is Base64URL?
Base64URL is a URL-safe variant that uses - instead of + and _ instead of /, and omits padding (=). This tool supports both standard and URL-safe Base64.