What a Base64 data URI is
A data URI puts a file's contents directly into the place a URL would normally go: <img src="data:image/png;base64,iVBORw0…">. The browser decodes it instead of downloading anything. Base64 represents binary data with 64 safe text characters, which costs about 33% in size — a 30 KB PNG becomes roughly 40 KB of text — but it means the image can never go missing, because it is part of the HTML itself.
When inlining images is the right call
- Single-file pages you will email, share as one attachment or paste into the HTMLtoLink editor.
- Logos, icons and small illustrations under roughly 100 KB.
- HTML email signatures and templates, with the caveat that some email clients block data URIs.
For photo-heavy pages it is the wrong call: a 2 MB photo becomes 2.7 MB of text that must download before anything after it renders. Upload those sites as a ZIP instead — see ZIP website to a link.
SVG gets special treatment
SVG is already text, so this tool URL-encodes it instead of Base64-encoding it. The result is smaller and still readable, and works everywhere an image URL does.