A Base64 media decoder converts a base64-encoded image, audio or video data URI back into the original file and renders a preview, so you can see what a base64 blob actually contains.
Example
data:text/plain;base64,U2lnbmFsIOKGkiBtZWFuaW5nSignal → meaning
MIME type: text/plain
Encoding: base64
Payload size: 18 bytesWhat is the Base64 Media Data URI Decoder?
Media inlined into HTML, CSS, JSON or an API response arrives as a data URI: data:image/png;base64,iVBORw0KGgo... The prefix declares the MIME type, the base64 flag says how the payload is encoded, and everything after the comma is the file itself. Without a decoder it is an opaque wall of characters.
Rendering it locally answers the two questions that matter: what is this, and how big is it. Base64 adds roughly 33% to the file size, so an inlined hero image that looked convenient in development can be the reason a stylesheet ships half a megabyte.
The magic bytes at the start of the decoded data are also a useful check on the declared MIME type. iVBORw0KGgo is a base64-encoded PNG header, /9j/ marks a JPEG, R0lGOD a GIF — a mismatch between the declared type and the real signature is a common sign of a mangled payload or a deliberately mislabelled file.
How to use the Base64 Media Data URI Decoder
- Paste the full data URI, or just the base64 payload if you know the type.
- The media is rendered as a preview with its detected type and decoded size.
- Download the decoded file, or check the size before inlining it in production.
When to use it
- Seeing what an inlined image in a stylesheet or JSON response actually is.
- Recovering an image from an API response or email source.
- Measuring the real byte cost of an inlined asset.
Base64 Media Data URI Decoder at a glance
| Form | data: |
| Size overhead | +33% versus the raw file |
| PNG signature | Base64 starts iVBORw0KGgo |
| JPEG signature | Base64 starts /9j/ |
Frequently asked questions
How do I convert base64 to an image?
Paste the base64 string or the full data URI here — it is decoded and rendered as a preview you can download, entirely in your browser.
Why is my base64 image not displaying?
Usually a missing or wrong data: prefix, truncated payload, or whitespace and line breaks copied from a source file. The declared MIME type must also match the actual file signature.
Is base64 image data larger than the file?
Yes, by about a third. That is the cost of representing binary in a 64-character text alphabet — worth it for tiny icons, rarely worth it for photographs.
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