Penme is described as 'lightweight open source note taking app focused on privacy! All your data is stored in your device, none of your data never leaves your device (unless the user does something silly 😉 )' and is an website in the News & Books category. There are more than 100 alternatives to Penme, not only websites but also apps for a variety of platforms, including Windows, Mac, Android and iPhone. The best alternative is Joplin. It's not free, so if you're looking for a free alternative, you could try Standard Notes or Notion. Other great sites and apps similar to Penme are Google Keep (Free), Microsoft OneNote (Freemium), Evernote (Freemium) and Simplenote (Free, Open Source).
Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, can be copied, tagged and modified either from the applications directly or from your own text editor.
With so many tools, it's hard to keep everyone on the same page. Notion is a new tool that unifies them all. It's like Google Docs, but everything is organized and discoverable by your team. Real collaboration in real-time.