What input format does this expect?

A complete data URI starting with "data:image/jpeg;base64," or "data:image/jpg;base64," followed by the base64-encoded image data. Unlike some base64 decoders, this tool requires the full data URI prefix, not a bare base64 string.

Why does it require the MIME type prefix specifically?

Requiring an explicit image/jpeg (or image/jpg) declaration up front catches an obviously mismatched paste (like a PNG or PDF data URI) immediately, before wasting time decoding bytes that were never going to be a JPEG.

What if the MIME type says JPEG but the bytes aren't really one?

The decoded bytes are still double-checked against the real JPEG Start of Image marker (FF D8) after decoding, so a mislabeled or corrupted data URI is caught rather than producing a broken download.

Is this the exact reverse of the JPG to Data URI converter?

Yes, feeding this tool the output of JPG to Data URI Converter reproduces the original file exactly, byte for byte.

Data URI to JPG Converter - Decode an Inline Image

Overview

Introduction

If you have a JPEG image embedded as a data URI, from a browser's DevTools, an exported email, or a saved CSS file, this tool decodes it back into a real, downloadable file.

Everything happens locally in your browser.

What Is Data URI to JPG Converter?

A strict data URI decoder built specifically for JPEG payloads: it requires the full data:image/jpeg;base64, (or image/jpg) prefix up front, decodes the base64 body, and validates the result against the JPEG file signature.

It rejects wrong-MIME-type and malformed payloads with specific error messages rather than silently producing a broken file.

How Data URI to JPG Converter Works

The input is checked against a pattern requiring a data: URI with an image/jpeg or image/jpg MIME type and a base64, marker before anything is decoded.

The remaining base64 text is decoded into raw bytes via atob (or Buffer under Node), and the first 2 bytes are compared against the JPEG SOI marker (FF D8) before the file is offered for download.

When To Use Data URI to JPG Converter

Use it whenever you have a JPEG image represented as a data URI, copied from a browser's inspector, an HTML file, or a CSS stylesheet, and need the actual image file back.

It's also useful for recovering an image from an exported single-file HTML page or email template.

Often used alongside JPG to Data URI Converter, Data URI to PNG Converter and Base64 to JPEG Converter.

Features

Advantages

Runs entirely client-side; pasted data never leaves your browser.
Requires an explicit JPEG MIME declaration, catching an obviously wrong paste immediately.
Double-validates the decoded bytes against the real JPEG signature, not just the claimed MIME type.

Limitations

Only full data URIs with an image/jpeg or image/jpg MIME type are accepted; a bare base64 string with no data: prefix is rejected (use the JPG to Hex/Data URI round trip if you have one without a prefix).
A single mistyped or missing base64 character shifts every subsequent byte, so manually edited data URIs need to be exact.

Examples

Standard data URI

Input

data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQ...

Output

A decoded JPG file, ready to download

The MIME type and base64 marker are both required exactly as shown.

Wrong MIME type

Input

data:image/png;base64,iVBORw0KGgo...

Output

Error: "Input must be a data URI starting with 'data:image/jpeg;base64,' (or 'image/jpg')."

A PNG-declared data URI is rejected immediately rather than attempting to decode it as a JPEG.

Best Practices & Notes

Best Practices

Copy the data URI directly from its source rather than retyping it, since a single wrong character corrupts the whole decoded file.
Pair with the JPG to Data URI converter to confirm a round trip reproduces your original file exactly.

Developer Notes

A pure function over a string: validates the data URI prefix and MIME type with a regex, decodes the base64 body into a Uint8Array, then checks the JPEG SOI marker; no DOM or canvas involved until the component paints the result for preview/download.

Data URI to JPG Converter Use Cases

Recovering a JPEG from a saved single-file HTML page or email template
Extracting an inlined image from a CSS background-image declaration
Rebuilding a file after manually editing a data URI for testing

Common Mistakes

Pasting a bare base64 string without the required 'data:image/jpeg;base64,' prefix, which this tool intentionally rejects.
Assuming any image data URI will work; a PNG or WebP data URI is correctly rejected here.

Tips

If decoding fails, double-check the MIME type in the prefix matches image/jpeg or image/jpg exactly.
Use the JPG to Data URI converter first if you need a fresh, guaranteed-correct data URI to test against.

Data URI to JPG Converter