I’ve used https://www.photopea.com before, pretty good! It’s web based photoshop :)

https://app.diagrams.net/

Edit: https://databasediagram.com/

https://penpot.app/

https://github.com/xibyte/jsketcher

https://app.sketchup.com/app?hl=en

https://www.onshape.com/en/

lucidchart.com, miro.com, witeboard.com are all fantastic. Excalidraw is good too

Do Electron apps count as web-based?

1. VSCode - No explanation needed
2. Obsidian - Note taking app on crack
3. Postman - API designer/debugger

Godot has an online version too

https://editor.godotengine.org/releases/latest/

https://www.plantuml.com/plantuml

https://sourcegraph.com/search

I visit this Unix timestamp converter site way too often… https://www.unixtimestamp.com/index.php

Canva is really good for content creators