The best alternatives to producteev are Toby, Azendoo, and MeisterTask. If these 3 options don't work for you, we've listed a few more alternatives below.
Toby is an award-winning Chrome extension that you need to have!
Bookmarks are for books, not browsers. Organize your browser tabs into Toby so you can access key resources in one-click instead of seven.
Tobidun is a modern task management app with many useful features in a simple, intuitive interface. - Sync across devices for free - Add tags - Filter by due date - More awesome features are coming (subtasks, projects, you suggestions)