I’ve developed the https://app.spera.io This is the Project Management Website similar Trello and Basecamp. Project is divided into 2 parts: Worker and Client. Worker has 2 types: Admin and Member Admin can create the project, invite the members and assign the tasks to members. Member follow the instruction of Admin. Worker can track the working time and tracked time is used for hourly invoice. After work don or milestone achieved, Admin Worker request the Invoice to Client. Client check the progress of project and release the payment.