An invoicing and billing application, Harvest has received great reviews all over the web. It tracks your projects, making sure you are keeping to deadlines and incorporating time tracking, invoicing and payment tools. They have a human-run customer services department via Twitter. The software integrates with a large number of associated apps and being web-based, you won’t need to download, but this also means you rely on the input of your employees as regards time worked on a project. Apps are available for iOS and Android.