Floci is a high-performance, open-source AWS emulator designed to provide developers with a reliable, local AWS environment. Built with Quarkus Native, it achieves sub-second startup times, starting in just 24ms, and maintains a minimal idle memory footprint of 13 MiB. It serves as a drop-in replacement for existing AWS emulation solutions, requiring no authentication tokens or restrictive pricing models, and operates entirely under an MIT license to ensure long-term accessibility and flexibility.

The tool functions as a sophisticated proxy and orchestrator that allows developers to run AWS services locally by mapping requests to a single endpoint. Unlike solutions that rely on mocking alone, Floci leverages real Docker engines for data-intensive services, providing high protocol fidelity for complex components such as databases, caches, and stream processors. This approach enables seamless local development and integration testing with consistent, real-world AWS behaviors.

Some of the key features are:

• Native Performance: Built using Quarkus Native and GraalVM, offering significantly faster startup times and lower resource consumption compared to alternatives.
• True Parity Engines: Uses actual Docker containers for services like RDS (PostgreSQL/MySQL), ElastiCache (Redis), EKS, and MSK to ensure identical behavior to production AWS.
• Drop-in Compatibility: Fully wire-compatible with standard AWS SDKs and CLI tools, allowing integration with zero code changes by simply updating the endpoint URL.
• Multi-Account Isolation: Supports complex local environments by providing isolated storage contexts for different AWS account IDs within a single instance.
• Robust Security Emulation: Provides real IAM authentication and SigV4 signature validation across major services including Lambda, RDS, and ECS.
• Optional HTTPS/TLS: Auto-generates self-signed certificates for local TLS-sensitive code paths without manual management overhead.
• Extensive Service Coverage: Includes 45 AWS services, including exclusive features not found in other community-edition emulators like Route53, Auto Scaling, and Textract.

Operationally, Floci runs as a lightweight Docker container. Developers initiate the service via standard Docker or docker-compose configurations. Once running, it occupies port 4566 and listens for standard AWS API requests. By setting the AWS_ENDPOINT_URL environment variable in their development environment, developers redirect their standard AWS CLI and SDK traffic to the local emulator. For services that require container backends (e.g., RDS or Lambda), Floci automatically manages the lifecycle of these secondary containers, ensuring that the local environment remains clean and ephemeral as required by CI/CD workflows.

Some common use cases include:

• CI/CD Integration: Using Floci in automated testing pipelines to execute integration tests against AWS services without requiring a live cloud account or incurring costs.
• Local Development: Developing and debugging serverless applications locally, including Lambda functions, SQS queues, and S3 buckets, with instant feedback loops.
• Complex Architecture Prototyping: Validating event-driven architectures involving MSK, Kinesis, and EventBridge on a local machine before deploying to production.
• Database Testing: Testing application interactions with RDS and Redis, including full IAM-based authentication flows, locally without the need for managed database instances.