What this project does

Floci is a free, open source local AWS emulator positioned as a plug and play replacement for LocalStack, used for local development, testing, and CI. It simulates a large number of AWS services locally with no cloud account, no auth token, and no paid feature gates. You just run docker compose up, or use the official CLI with floci start, then point your existing AWS SDK, CLI, Terraform, CDK, OpenTofu, or test suites at http://localhost:4566 and your existing workflow keeps working. To run this kind of containerized local service on Windows, WSL2 with Docker is a common combo, covered in Install and Set Up WSL2 on Windows to Run Linux.

What problem it solves

LocalStack Community Edition announced its sunset in March 2026, requiring an auth token and freezing security updates, so many local cloud development workflows faced a migration. Floci steps into that gap with an "unconditional" alternative: no account or token, continued security updates, and extremely fast startup (native image about 24 ms, idle memory about 13 MiB, Docker image about 90 MB). For Lambda, RDS, ElastiCache, Neptune, ECS, EC2, MSK, EKS, OpenSearch, and CodeBuild it uses real Docker containers rather than shallow mocks, giving higher fidelity.

Language and tech architecture

The primary language is Java on the Quarkus framework. It receives AWS wire protocol requests on port 4566 via an HTTP router (JAX-RS / Vert.x), split into three service classes. Stateless in process services include SSM, SQS, SNS, IAM, STS, KMS, Secrets Manager, Cognito, EventBridge, Step Functions, CloudFormation, and API Gateway. Stateful in process services include S3, DynamoDB, and DynamoDB Streams. Container services run real Docker, covering Lambda, ElastiCache, RDS, Neptune, ECS, EC2, MSK, EKS, OpenSearch, and CodeBuild, while Athena runs real SQL through floci-duck (a DuckDB sidecar). The StorageBackend supports memory/persistent/hybrid/wal modes. Beyond CLI and Docker Compose, native binaries for Linux, macOS, and Windows (about 40 MB) are provided, along with Testcontainers modules for Java, Python, Node.js, Go, and .NET, and compatibility with Terraform, OpenTofu, and AWS CDK.

License

MIT

It lands precisely in the window opened by LocalStack Community Edition's retirement, winning migrating users with a hard contrast of token free, MIT licensed, faster, smaller, and real Docker fidelity, and its drop in compatibility (port 4566, credentials, SDK config all shared) lowers switching cost. It gained about 1,090 stars on its launch day.

Project address

GitHub repository https://github.com/floci-io/floci (official site https://floci.io/floci/ )