This part of filemerge.net allows you to upload a zip file containing HTML files. Once uploaded, the utility will display the uploaded zip file. Click on the directory with the same name. Next, click the HTML file for which you want the image references replaced with inline base-64 encoded data. The result will be a single HTML file with embedded images that you can save and easily copy, paste, or upload. Images must be coded as <img src="my-image.png"> (other optional attributes, like 'class="whatever"' will remain untouched). No spacing should exist between src and the last double quote. The src value must be enclosed in double-quotes. This utility works handily from Google documents downloaded as zipped HTML files.