Org mode - Org: an Emacs Mode for Notes, Planning, and Authoring
Muster - Muster is a grassroots advocacy tool that enables professional associations and nonprofits to engage their membership in the legislative process.
Taskade - Make lists, organize your thoughts, and be inspired to get things done. Taskade is a collaborative space for your tasks.
NationBuilder - The world's first platform for leaders, handcrafted from scratch to help you grow your community and lead them to action.
Simplenote - The simplest way to keep notes. Light, clean, and free. Simplenote is now available for iOS, Android, Mac, and the web.
NGP VAN - NGP VAN offers an integrated platform that combines the best fundraising, compliance, field, organizing, and new media products.