How to use Data URI to File
The Data URI to File tool decodes any base64-encoded data URI — images, PDFs, audio, JSON, fonts, or binary blobs — directly in your browser and gives you a one-click download. Paste a data:*;base64,... string from an API response, HTML source, or CSS file and retrieve the original file in seconds. Because all decoding uses the Web Crypto and Blob APIs locally, nothing is ever transmitted to a server, keeping your payloads completely private.
- Copy the full data URI string from your source (API response, HTML attribute, or CSS file).
- Paste it into the input field — the tool accepts any data URI starting with data: regardless of MIME type.
- Click "Decode to File" to decode the base64 payload into the original binary.
- Inspect the detected MIME type, file extension, and byte size shown in the result card.
- Click the download button to save the decoded file with the correct extension.
Your data never leaves your device — 100% private processing.
What is a data URI and when is it used?
A data URI (also called a data URL) is a URI scheme defined by RFC 2397 that lets you embed binary file content as base64-encoded ASCII text directly inside a string. The format is data:<mimeType>[;charset=<encoding>];base64,<base64data>. Browsers originally introduced data URIs to embed small images in CSS and HTML without an extra HTTP request, avoiding a round-trip to a server. Today they appear widely in REST API responses that transmit files as JSON strings, in PDF generators that inline image assets, in JWT claims carrying embedded avatars or certificates, and in export formats from design tools. The main trade-off is size: base64 encoding inflates binary data by roughly 33 %, so data URIs are best reserved for small-to-medium assets.
| MIME type | Extension | Typical use |
|---|---|---|
| image/png | .png | Lossless images, logos, icons in CSS/HTML |
| image/jpeg | .jpg | Photographs embedded in API payloads or email HTML |
| image/svg+xml | .svg | Vector graphics in HTML templates |
| application/pdf | PDF documents returned from document generation APIs | |
| application/json | .json | JSON config or schema embedded in a larger payload |
| font/woff2 | .woff2 | Web fonts inlined in CSS @font-face for offline-first apps |
| audio/mpeg | .mp3 | Short audio clips embedded in notification payloads |
How base64 encoding works inside a data URI
The base64 algorithm maps every group of three input bytes to four ASCII characters drawn from a 64-character alphabet (A–Z, a–z, 0–9, +, /). If the input length is not a multiple of three, one or two = padding characters are appended. This means a data URI payload is always a multiple of four characters long and consists exclusively of printable ASCII — safe to embed in JSON strings, HTML attributes, and URL-encoded forms. The URL-safe variant (used in JWTs and some APIs) replaces + with - and / with _ and omits the trailing padding, so it can be used directly in a URL path or query string without percent-encoding. This tool handles both standard and URL-safe variants automatically.
Worked examples
Decode a PNG data URI
Inputs: data:image/png;base64,iVBORw0KGgo...
Result: .png file downloaded — MIME: image/png, ~1.4 KB
Decode a JSON data URI
Inputs: data:application/json;base64,eyJrZXkiOiJ2...
Result: .json file downloaded — MIME: application/json, 12 B
Glossary
- Data URI
- An RFC 2397 URI scheme that encodes file content as a base64 ASCII string prefixed with the MIME type.
- MIME type
- A two-part identifier (type/subtype) that tells browsers and APIs what kind of data a file contains, e.g. image/png or application/json.
- Base64
- A binary-to-text encoding that represents arbitrary bytes using a 64-character ASCII alphabet, adding roughly 33 % overhead.
- Blob
- A browser object that represents raw binary data. This tool converts the decoded bytes into a Blob so the browser can offer it as a download.
- URL-safe Base64
- A variant of base64 that substitutes + → - and / → _ and drops padding, so the string is safe to embed in URLs without percent-encoding.
Related reading
Frequently Asked Questions
Why use Data URI to File?
- Decode any base64 data URI to its original file without a server round-trip
- Automatic MIME type detection sets the correct file extension for download
- Inline preview for images and PDFs before saving to disk
- Handles URL-safe base64 (- and _ variants) transparently alongside standard base64
- Works with any MIME type — images, PDFs, audio, fonts, archives, and binary blobs
Common use cases
- Extract an embedded image from a REST API JSON response for offline inspection
- Save a PDF returned as a data URI from a document generation API
- Recover a font file inlined in CSS as a data:font/woff2;base64 string
- Download a binary attachment from a webhook payload that encodes files as base64
- Preview and verify an image data URI before embedding it in HTML or an email template
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