Decode Base64 to text. Preview images from data URIs.
Decode Base64 strings back to text. Supports standard Base64 and data:URI format. Useful for debugging API responses and tokens.
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Open AI chat →Base64 Decoder Online — String and Image Decoding
The decoder converts Base64 strings back to text or binary data. Automatically detects Data URIs (PNG, JPEG, GIF, WebP images) and shows a preview. All operations run in the browser without sending data to a server.
What Is Base64 Decoding
Base64 decoding is the reverse of encoding: every 4 Base64 characters are converted back to 3 bytes of original data. Trailing = characters (padding) indicate the number of padding bytes.
Image Preview (Data URI)
A Data URI is an embedded image: data:image/png;base64,iVBOR.... The decoder auto-detects the type from the Base64 signature: iVBOR→PNG, /9j/→JPEG, R0lG→GIF, UklG→WebP.
Decoding Security
Base64 is encoding, not encryption. Decoded data may contain executable code or malicious HTML. Never insert decoded content directly into the DOM without validation.
Frequently Asked Questions
Why does decoded text look like garbage?
Either the string is not valid Base64, or the original data is binary (not text).
How to decode Base64url (JWT)?
Base64url uses - instead of + and _ instead of /, without padding. For JWT analysis use the JWT decoder.
For encoding use the Base64 encoder, for JWT — JWT decoder.
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