Helix

Helix is a modal editor that puts the selection first: you can always see what the next command will act on before you run it. Syntax highlighting, multiple cursors and language support come built in — there are no plugins to install.

The demo opens a small Rust program. Press w a few times and watch each word get selected as the cursor moves, x then c to change a whole line, and % then s to put a cursor on every copy of a name and rename them all at once. Space is the menu key for everything you have not memorised. The VM is private to your browser tab; nothing you type leaves it.