OpenFaaS

OpenFaaS (Functions as a Service) is an open-source serverless framework for Kubernetes and container orchestrators, enabling developers to deploy event-driven functions and microservices without managing infrastructure. Created by Alex Ellis in 2017 and now a CNCF Sandbox project, OpenFaaS simplifies the serverless experience by packaging functions as OCI-compatible Docker containers that run on any Kubernetes cluster or Docker Swarm. Key features include: the faas-cli command-line tool for creating, building, pushing, and deploying functions with a single command (faas-cli up), function templates in multiple languages (Node.js, Python, Go, Ruby, C#, Java, Rust, PHP, Swift, Bash, Haskell) with custom templates via template stores, auto-scaling based on request rate using the OpenFaaS queue-worker and Prometheus metrics (scales from zero to thousands of replicas), connectors and event triggers via the OpenFaaS Event Connector SDK (supporting Kafka, NATS, AWS SQS, cron, MQTT, and custom event sources), function-level secrets management via Kubernetes secrets, built-in Prometheus metrics and Grafana dashboards for monitoring function invocations, latency, and error rates, asynchronous execution mode with built-in queuing, custom domains and TLS via Ingress controllers, and the OpenFaaS Cloud platform for GitOps-based continuous deployment (automatically building and deploying functions from the repository on each push). As of 2026, OpenFaaS has over 25,200 stars.