PNG to Data URI Converter

Reads a PNG file's raw bytes, verifies its PNG file signature, and base64-encodes them into a full data:image/png;base64,... URI, entirely in your browser, so the image can be embedded inline without a separate file request. A free online tool from Staaarter, right in your browser.

Runs locallyUpdated 2026-07-26

Overview

Introduction

A data URI packages a file's entire content into a single text string, letting you embed a small image directly in HTML, CSS, or JSON without a separate file request.

This tool builds that string from an uploaded PNG entirely in your browser.

What Is PNG to Data URI Converter?

A byte-level converter that validates an uploaded file's PNG signature, then base64-encodes its exact bytes and wraps them in the data:image/png;base64,... scheme defined by RFC 2397.

The result is a self-contained, pasteable representation of the image.

How PNG to Data URI Converter Works

The uploaded file is read as raw bytes; the first 8 bytes are checked against the standard PNG signature before anything else happens, so non-PNG files are rejected up front.

The bytes are then base64-encoded and prefixed with the data:image/png;base64, scheme identifier to form the final URI.

When To Use PNG to Data URI Converter

Use it to inline a small icon or logo directly into a stylesheet or HTML document, avoiding an extra HTTP request for tiny assets.

It's also useful for quickly generating a self-contained image string to paste into an email template, a design tool, or an API request body.

Features

Advantages

  • Runs entirely client-side; the image is never uploaded to a server.
  • Produces output that's immediately usable anywhere a URL is accepted, no further assembly required.
  • Verifies the file is a genuine PNG before encoding, rather than trusting its extension.

Limitations

  • Base64 encoding increases effective size by roughly a third, making this a poor fit for large images.
  • Inline data URIs bypass the browser's normal image cache, which can hurt performance if the same image repeats across many pages.

Examples

Small logo

Input

A 2 KB PNG logo

Output

data:image/png;base64,iVBORw0KGgo... (about 2.7 KB of text)

The output is roughly 33% larger than the source file, typical of base64 encoding.

Non-PNG file

Input

A JPEG renamed to logo.png

Output

Error: "This file doesn't start with a valid PNG signature."

The signature check inspects actual bytes, catching mismatched extensions.

Best Practices & Notes

Best Practices

  • Reserve inline data URIs for small, frequently-reused icons rather than large photos.
  • Double-check unfamiliar files are genuinely PNGs before relying on the output — the signature check will catch a mismatch.

Developer Notes

Wraps the same pure byte-reading and base64-encoding logic already shipped in png-to-base64-converter, exposed under the name people search for when they specifically want a full data: URI rather than a bare base64 string.

PNG to Data URI Converter Use Cases

  • Embedding a small logo directly in an HTML email template
  • Generating a CSS background-image value with no extra network request
  • Producing an inline image field for an API payload

Common Mistakes

  • Using this for large photos, producing an impractically long string.
  • Assuming the output is a compressed or optimized version of the image — it's a byte-exact encoding of whatever was uploaded.

Tips

  • Paste the output directly into an <img src="..."> to preview it instantly in a browser.
  • If the resulting string is too long to be practical, compress or resize the PNG first.

References

Frequently Asked Questions