Data URI Scheme - Disadvantages

Disadvantages

• Data URIs are not separately cached from their containing documents (e.g. CSS or HTML files) so data are downloaded every time the containing documents are redownloaded.
• Content must be re-encoded and re-embedded every time a change is made.
• Internet Explorer through version 7 (approximately 5% of web traffic as of September 2011), lacks support. However this can be overcome by serving browser specific content.
• Internet Explorer 8 limits data URIs to a maximum length of 32 KB. (Internet Explorer 9 does not have this limitation)
• In IE 8 and 9 data URIs can only be used for images, but not for navigation or Javascript generated file downloads.
• Data are included as a simple stream, and many processing environments (such as web browsers) may not support using containers (such as multipart/alternative or message/rfc822) to provide greater complexity such as metadata, data compression, or content negotiation.
• Base64-encoded data URIs are 1/3 larger in size than their binary equivalent. (However, this overhead is reduced to 2-3% if the HTTP server compresses the response using gzip)
• Data URIs do not carry a filename as a normal linked file would. When saving, a default filename for the specified MIME type is generally used.
• Referencing the same resource (such as an embedded small image) more than once from the same document results in multiple copies of the embedded resource. In comparison, an external resource can be referenced arbitrarily many times, yet downloaded and decoded only once.
• Data URIs make it more difficult for security software to filter content.