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Lem vs Helix: catalog facts
Lem	Helix
Free Free and open source.	Free Free and open source under the MPL 2.0.
macOS, Linux, Command line	Windows, macOS, Linux, Command line
Extensible in Common Lisp while running Emacs-like and Vim-like modes	Language server and tree-sitter support without installing anything Selection-first editing makes multiple cursors a first-class tool
Extending it requires learning Common Lisp GUI is in transition from SDL2 to a webview version	No plugin system, so anything missing stays missing Selection-first keys are genuinely different from Vim muscle memory
Downloadable app	Downloadable app
Open source	Open source
License not stated	License: MPL-2.0
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 21, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.