dotcl — a Common Lisp implementation on .NET — compiled to WebAssembly. Not a subset: 21932 of the 21937 tests in the ANSI test suite pass. Nothing is installed and nothing is sent anywhere; the Lisp runs in the tab.
Chapters you can edit and run. Errors arrive carrying restarts, and any block can be shared as a link.
A canvas filled from Common Lisp, with the source sitting in the page as a
<script type="text/common-lisp"> the browser leaves alone.