There are many popular open source projects built using Go. Here are a few examples:
Kubernetes: A container orchestration platform that automates the deployment, scaling, and management of containerized applications.
Docker: A platform that allows developers to build, package, and distribute applications as containers.
Prometheus: A monitoring system and time series database that collects metrics from configured targets at given intervals.
Etcd: A distributed key-value store that provides a reliable way to store and manage data across a cluster of machines.
CockroachDB: A distributed SQL database that provides high availability and strong consistency.
InfluxDB: A time-series database that is optimized for storing and querying large amounts of time-stamped data.
Hugo: A fast and flexible static site generator that allows you to build websites with speed and ease.
Gogs: A self-hosted Git service that is easy to use, lightweight, and written in Go.
Grafana: A platform for visualizing and analyzing data from multiple sources, including time series databases, logs, and metrics.
Consul: A service discovery and configuration management tool that provides a way to discover and connect services across distributed infrastructure.