# Base64 Media Data URI Decoder

> Preview and decode base64 image, audio and video data URIs.

- Page: https://decoder.tools/base64-media-decoder
- Category: Image, Media & Steganography
- Status: live, runs in the browser
- Last reviewed: 2026-10-23

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

```text Input
data:text/plain;base64,U2lnbmFsIOKGkiBtZWFuaW5n
```

```text Output
Signal → meaning
MIME type: text/plain
Encoding: base64
Payload size: 18 bytes
```

## What 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

1. Paste the full data URI, or just the base64 payload if you know the type.
2. The media is rendered as a preview with its detected type and decoded size.
3. 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:<mime>;base64,<payload> |
| Size overhead | +33% versus the raw file |
| PNG signature | Base64 starts iVBORw0KGgo |
| JPEG signature | Base64 starts /9j/ |

## FAQ

### 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.