About

The Data URI scheme (defined in RFC 2397) allows developers to embed small files directly inline within documents as a string. While highly efficient for reducing HTTP requests for small assets, these strings are inherently unreadable to humans. This tool performs high-fidelity, client-side extraction and decoding of the embedded payload back into its native ASCII or UTF-8 text format.

Using a background thread (Web Worker), this converter parses the media type header, identifies the encoding method (typically base64 or percent-encoded URL formatting), and safely decodes the payload. It utilizes the native TextDecoder API to ensure that multi-byte Unicode characters are accurately reconstructed without data corruption - a common risk when using rudimentary decoding scripts.

Formulas

The parsing engine isolates the components of a Data URI based on the following structural definition:

URI = data:{

mediatype∅ (defaults to text/plain)

[

;base64∅

],data

Reference Data

MIME Type Parameter	Typical Encoding	Decoded Output Type	Use Case
text/plain	URL-encoded or Base64	Plain Text	Simple inline text payloads
text/html	Base64	HTML Markup	Inline iframes or secure contexts
image/svg+xml	URL-encoded	XML/SVG Markup	Inline vector graphics in CSS
application/json	Base64	JSON String	Embedded configuration data
application/javascript	Base64	JS Source Code	Inline executable scripts
text/css	URL-encoded	CSS Rulesets	Inline stylesheets

Frequently Asked Questions

If the Data URI contains a binary file (such as an image/png, audio/mp3, or compiled executable), decoding it to ASCII text will result in unreadable characters. ASCII/UTF-8 decoding is only useful when the underlying payload is text-based (like HTML, SVG, or JSON).

Unlike basic converters that rely solely on the native "atob" function (which fails on non-Latin1 characters), this tool converts the Base64 payload into a raw Uint8Array buffer. It then processes that buffer using the modern TextDecoder API, ensuring perfect reconstruction of complex UTF-8 multibyte characters.

No. The entire decoding process occurs entirely within your browser using a dedicated local Web Worker. No data is transmitted externally, ensuring complete privacy for sensitive embedded configurations or tokens.

According to RFC 2397, if the media type is omitted (e.g., 'data:;base64,SGVsbG8='), the parser automatically assumes a default MIME type of "text/plain;charset=US-ASCII".