How to svg data uris: browser compatibility, encoding rules, and troubleshooting
- Step 1Check your MIME type declaration — SVG data URIs must use data:image/svg+xml as the MIME type prefix. Using data:image/svg or omitting the MIME type causes the browser to reject the URI.
- Step 2Validate your encoding — Paste your data URI into the browser address bar and press Enter. If the SVG renders correctly, the encoding is valid. Unescaped # characters in the SVG source are a common failure point.
- Step 3Test the CSS background rendering — Create a minimal test: a div with width, height, and background-image set to your data URI. Test in Chrome, Firefox, and Safari to confirm consistent rendering.
Frequently asked questions
Is SVG data URI supported in all modern browsers?+
Yes. SVG data URIs (both URL-encoded and base64) are supported in Chrome, Firefox, Safari, and Edge. IE11 supports them in img but with inconsistent CSS background-image behaviour.
Why does my SVG data URI work in Chrome but not Firefox?+
Firefox is strict: the # character must be encoded as %23, and the SVG must have a proper namespace declaration. The JAD tool handles both automatically.
Is there a size limit for CSS data URIs?+
Browsers support data URIs of at least 2 MB. The practical limit is CSS file size — large data URIs bloat your stylesheet and slow CSS parsing.
Can I use CSS variables inside a data URI SVG?+
No. SVGs used as CSS data URIs or img src are isolated from the parent document's CSS cascade. CSS custom properties set on :root do not propagate into data URI SVGs.
Privacy first
Every JAD SVG tool runs entirely in your browser using the DOM API and Canvas. Your SVG files never leave your device — verified by zero outbound network requests during processing.