Open Source Alternatives to Missive

A collaborative email client designed for teams to manage shared inboxes. The software allows multiple users to discuss emails internally via a chat layer before sending responses and organize work through shared tasks, tags, and internal statuses. It includes automation rules for repetitive manual tasks and integrates with over 25 external applications to provide additional context within the inbox. The platform is used by small businesses and professional services in industries such as accounting, law, and e-commerce to coordinate communication and track team capacity. Users can turn emails into tasks to see what team members are working on across different timeframes. It is deployed as a cloud-based application accessible via browser and dedicated downloads.

Whether you want to cut software costs or escape vendor lock-in, these open source alternatives to Missive give you an option you fully own. You can self-host them, so your data stays on infrastructure you control. This page lists 1 open source alternative to Missive. The most popular is UnInbox. It uses the AGPL-3.0 license and ships an official Docker image.