InfluxDB is an open source time series platform. This includes APIs for storing and querying data, processing it in the background for ETL or monitoring and alerting purposes, user dashboards, and visualizing and exploring the data and more.
From project planning and source code management to CI/CD and monitoring, GitLab is a single application for the entire DevOps lifecycle.
Joplin - an open source note taking and to-do application with synchronization capabilities for Windows, macOS, Linux, Android and iOS.