oneheap is described as 'A web based note, task, project and appointment organizer with team features' and is a Task Management Software in the Office & Productivity category. There are more than 100 alternatives to oneheap for a variety of platforms, including Online / Web-based, iPhone, Windows, Android and Mac. Most alternatives are Task Management Software and Team Collaboration Apps. The best alternative is Joplin. It's not free, so if you're looking for a free alternative, you could try Standard Notes or Google Keep. Other great apps like oneheap are Microsoft OneNote (Freemium), Trello (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.
Todoist is a task manager thats useful, fast and easy to use. Accomplish more, every day. Millions of people rely on Todoist to get things done. Todoist lets you manage your tasks anywhere. At home. At school. At work. Online. Offline. And on 13 platforms and devices.