You can find my Webmidi apps here: https://www.floydsteinberg.com/extension/www.floydsteinberg.com/webmidi/
Here's a convolution reverb running in your browser: https://www.floydsteinberg.com/extension/www.floydsteinberg.com/webmidi/fx.html
And here's a sequencer running in your browser: https://www.floydsteinberg.com/extension/www.floydsteinberg.com/sequencer/