Data URI Decoder

Paste a data: URI (RFC 2397) and decode it into its parts: the MIME type, media-type parameters such as charset, whether the payload is Base64 or percent-encoded, the decoded byte size, and the payload itself. Printable payloads are shown as decoded text; binary payloads get a detected file type and a hex preview. Whitespace inside Base64 is tolerated. Runs entirely in your browser; nothing is uploaded.

About this tool

A data URI (also called a data URL) embeds a small file directly inside a URL instead of pointing at one. It has the form data:[<mediatype>][;base64],<data> — for example data:text/plain;base64,SGVsbG8= or data:image/png;base64,iVBORw0KGgo.... They show up in CSS background-image rules, inline <img src> tags, email HTML, JSON payloads, and copy-pasted screenshots.

This decoder reverses one. Paste a data: URI and it splits out:

the MIME type (defaulting to text/plain when the URI omits it);
any media-type parameters, such as charset;
the encoding — Base64 or percent-encoded (URL) text;
the decoded size in bytes; and
the payload itself: printable content is shown as decoded text, while binary content (images, PDFs, fonts, …) is reported with its file type detected from the magic bytes plus a hex preview.

It tolerates whitespace and line breaks inside the Base64, accepts the bare data:,... short form, and preserves commas that appear inside the data.

Everything runs locally in your browser via WebAssembly — the data URI you paste is never uploaded to a server.

Examples

data:text/plain;charset=utf-8,Hello%20World → text Hello World
data:text/html;base64,PGgxPkhpITwvaDE+ → the HTML <h1>Hi!</h1>
data:image/png;base64,iVBORw0KGgo= → detected file type image/png

FAQ

My data URI decodes to an image — can I see or save the picture?

Binary payloads aren't rendered here; instead you get the file type sniffed from the magic bytes (e.g. image/png), the decoded byte size, and a hex preview of the first 64 bytes. To view the image itself, paste the whole URI into your browser's address bar or an <img src> attribute.

Why does it say the charset is US-ASCII when I never specified one?

That's the RFC 2397 rule: a data URI with no media type (or a bare data:,...) defaults to text/plain;charset=US-ASCII, so the decoder reports that default explicitly rather than leaving the field blank.

The Base64 I copied has line breaks in it — will that break decoding?

No. Whitespace and newlines inside the Base64 payload are stripped before decoding, which is handy for URIs copied out of wrapped CSS or email HTML. Commas after the first one are preserved as data, so percent-encoded text containing commas decodes intact.

Is there a size limit on what it can decode?

Decoding happens fully in your browser, so nothing is uploaded. Text output is truncated at 100,000 characters and the binary hex preview shows the first 64 bytes — the reported decoded size and a truncated flag always reflect the full payload.

Developer & Automation Access

Run it from the terminal

Same engine as this page, headless — via the gizza CLI:

gizza tool data-uri-decode "data:text/plain;charset=utf-8;base64,SGVsbG8sIFdvcmxkIQ=="

New to the CLI? Get gizza →

Open it by URL

Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:

https://gizza.ai/tools/data-uri-decode/?uri=data%3Atext%2Fplain%3Bcharset%3Dutf-8%3Bbase64%2CSGVsbG8sIFdvcmxkIQ%3D%3D

Machine-readable descriptor: tool.json — title + parameters JSON Schema for agents.