A full extension list of the official Extended plan

[JokerQyou]

Some of the extensions in Extended plan are not open-sourced. But we could do the remaining.

[JokerQyou]

Editors

• Bold Editor
• Advanced Markdown
• Secure Spreadsheets
• Simple Task Editor
• Simple Markdown
• Plus Editor
• LaTeX Editor (It has different names: LaTeX editor, Math editor, Fancy Markdown Editor. Anyway it's a markdown editor with LaTeX support for math equations and consists of a two-panel split view)
• Minimal Markdown
• Code Editor
• Vim Editor
• TokenVault

[JokerQyou]

Components

• Folders (seems to be somewhat unstable for various edge cases, see its issues for detail. Might not worth bundling)
• Quick tags
• Action Bar
• GitHub Push

[JokerQyou]

Themes

• Midnight
• Focused
• Futura
• Solarized Dark
• Titanium
• Dynamic
• No Distraction

[JokerQyou]

Data Care

• FileSafe (FileSafe is actually open-sourced, see this comment, but it would require self-hosting yet another Ruby server)
• Dropbox Sync
• Google Drive Sync
• Microsoft OneDrive Sync
• Daily Email Backups
• FileSend encrypted sharing (the filesend server is open source software)
• Two-Factor Authentication
• Note History

The cloud drive syncing solutions seems to be included in a single package called CloudLink, but is officially stated as not open-sourced.
Most of these data care solutions are at the core business model of StandardNotes, so they are all close-sourced. If you want these feature, just consider subscribe to their Extended plan.

[JokerQyou]

Actions

• Listed (the listed server is an open source software hosted here)