Bookmarked Free Background Remover: Remove BG from HD Images for Free | Erase.bg (Erase.bg)
Make the background transparent for images of humans, animals, or objects. Download images in high resolution for free for e-commerce and personal use. No credit card needed.
Seems to do what it says on the tin. The transparent png files are larger. I added a red background and exported as jpg here. Could be useful in school, we normally use keynote & instant alpha. I switched the editor to Blocks added the image compare above and then switched back to classic to use the post kinds plugin.
Bookmarked Web Developer Tools - Programmer Tools - Online - Browserling (browserling.com)
We're obsessed with making web developers' lives easier at Browserling, so we created a collection of the most popular developer tools all in one place. We love simplicity so we made them very simple and obvious how to use. No ads, bloated dialogs, or useless checkboxes. Just tools. All free. Press button, get result. Here they are!

Lots of useful looking tools that work in the browser. EG: Convert TSV to XML, Convert CSV to JSON, URL encode/decode, HTML escape/unescape, huge bunch of text tools…