I'm using Asana API and trying to find all tasks in workspace without projects (This refers to the workspace without the project in which tasks are created). Is something like this possible in Asana API?
You can't filter the Asana API to return only tasks without projects. You would need to get every task in the desired workspace and then iterate through them to find the tasks with no project.
We plan to add more filtering options in the future. As of now, you can get /tasks by assignee (within a workspace), project, tag, section (of a board), completed_since, or modified since.