Toodledo is a popular online task manager and a to-do list that can be used by individuals or groups. Toodledo reviews are overwhelmingly positive. Its collaboration capabilities, however, are rather limited. Toodledo does not offer advanced project management tools either - no Gantt chart, no workload planning, time management, work reports or invoicing. It appears that Toodledo is available only online - there is no self-hosted version that you can install on your server for on-premise deployment or open source code that you can modify. If you outgrew Toodledo and need a task and project manager with more tools for group work and collaboration, take a look at Bitrix24.
* Please note that the information may have changed since the publication. For current prices and features please visit Bitrix24 pricing page.