Firecracker is an open-source virtualisation technology for running secure, multi-tenant container and function workloads, such as serverless services. Each workload runs in a lightweight virtual machine called a microVM. At its core is a virtual machine monitor that uses the Linux Kernel Virtual Machine (KVM) to create and run microVMs, deliberately leaving out unneeded devices and guest-facing features to reduce memory footprint and attack surface. It is software that platform operators run on their own Linux hosts, not a hosted service.
Firecracker was developed at Amazon Web Services, a US company, and is used by services such as AWS Lambda and AWS Fargate. It is released under the Apache License 2.0. Because it is software rather than a service, the location of workloads and data depends on where the operator runs it, so a European provider or organisation can use it in its own data centres with inspectable source code.