Data URL Parser — Extract MIME Type & Base64 Data
Parse data URLs to extract MIME type, encoding, and raw data content.
About Data URL Parser — Extract MIME Type & Base64 Data
Data URL Parser breaks down a data: URI into its MIME type, encoding method (base64 or URL-encoded), and raw data content. Useful for debugging embedded resources in HTML, CSS, and SVG files.
How to Use
- 1Paste the full data URI string into the input field.
- 2The tool parses and displays the MIME type, encoding, and data portion separately.
- 3Copy the individual components for use in your code or debugging workflow.
Features
- Parse data URIs into MIME type, encoding, and raw data
- Supports base64 and URL-encoded data URIs
- Useful for debugging inline assets in HTML/CSS/SVG
- Instant, browser-based parsing with no server calls
Anatomy of a Data URL
A data URL is a compact way to embed file content directly inside a text string. Parsing one reveals four distinct components, each carrying important information about the embedded resource.
The Data URL Structure
Every data URL follows the format: data:[mediatype];[encoding],[data]. The scheme is always data:. The mediatype (MIME type) identifies what kind of data is embedded — for example image/png, image/svg+xml, text/html, or application/json. If the mediatype is omitted, it defaults to text/plain;charset=US-ASCII. The encoding parameter is typically base64, indicating that the data portion has been Base64-encoded. If encoding is omitted, the data is interpreted as URL-encoded plain text. The data portion is everything after the final comma and contains the actual file content in the specified encoding format.
MIME Types in Data URLs
The MIME type tells the browser how to interpret and render the embedded content. Common MIME types in data URLs include: image/png and image/jpeg for raster images, image/svg+xml for vector graphics, image/gif for animated GIFs, image/webp for WebP images, text/html for inline HTML documents, text/css for stylesheets, application/javascript for scripts, and application/json for JSON data. When a browser processes a data URL, it uses the MIME type to determine which rendering pipeline to apply — the same way it uses the Content-Type response header for external files loaded over HTTP. The MIME type therefore controls whether the content is rendered as an image, executed as a script, or displayed as text.
URL-Encoded vs. Base64 Data URLs
Not all data URLs use Base64 encoding. For text-based content — particularly SVG images — URL encoding (percent-encoding) is an alternative that can produce shorter strings when the content consists mostly of ASCII characters. A URL-encoded data URL omits the base64 keyword and contains the raw text with special characters percent-encoded: data:image/svg+xml,%3Csvg.... This works well for small SVG icons and is more human-readable than Base64. However, Base64 is more universally supported and required for binary data like PNG or JPEG files. This parser identifies which encoding method is used and separates the data portion from the prefix accordingly.
Practical Uses of Data URL Parsing
Parsing data URLs is useful in debugging, security analysis, and understanding how embedded resources work in web applications.
Debugging Inline Assets in HTML and CSS
When reviewing minified or compiled CSS and HTML files, data URLs appear as long opaque strings that are difficult to inspect visually. This parser extracts the MIME type so you can immediately identify what type of asset is embedded, and separates the data from the prefix so you can pass it to the appropriate decoder — such as the Base64 to Image tool for visual inspection of embedded images. This is particularly useful when auditing third-party libraries or compiled design system outputs that inline assets, to verify what content is embedded and confirm it matches expectations.
Security and Content Auditing
Malicious scripts sometimes hide executable code inside data URLs to bypass content security filters that check file extensions or URL patterns. A data URL with MIME type application/javascript or text/html can execute arbitrary code when placed in certain HTML contexts. Security auditors reviewing HTML source code or CSP violation reports use data URL parsing to identify the MIME type of embedded data and determine whether it represents a security risk. The Content Security Policy default-src directive can restrict the data: URI scheme to prevent this attack vector, and understanding data URL structure is essential for crafting effective CSP policies that protect users from inline code injection.
FAQ
- What is a data URI?
- A data URI embeds file content directly in a URL string using the format: data:[MIME type];[encoding],[data].
- What MIME types are supported?
- Any MIME type can appear in a data URI. Common ones include image/png, image/jpeg, image/svg+xml, text/html, and application/json.
- Can I convert the data back to a file?
- If the data is a Base64-encoded image, use the Base64 to Image tool to decode and download the file.
- What is the structure of a data URL?
- A data URL follows the format: data:[mediatype][;base64],data. The mediatype is a MIME type like image/png, text/html, or application/json. If the data is binary (like most images), the ;base64 parameter indicates the data portion is Base64-encoded. If omitted, the data is URL-encoded text. Example: data:text/plain;charset=utf-8,Hello%20World is a plain text data URL without Base64. The data portion comes after the comma.
- Can data URLs be used for all resource types in HTML?
- Yes, data URLs work for: images (<img src="data:...">), stylesheets (<link href="data:...">), scripts (<script src="data:..."> — blocked by CSP in most modern browsers), iframes, fonts (@font-face src), and video/audio sources. Note that Content Security Policy (CSP) headers may block data URLs for scripts and iframes on secure sites. Data URLs for images in CSS background-image properties are widely supported and commonly used.
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