Floci — The Free AWS Local Emulator That Replaced LocalStack

In March 2026, LocalStack quietly ended an era. The community edition — the one thousands of developers relied on to test AWS services locally without burning cloud credits — now requires auth tokens and has frozen security updates. No more free ride. If you weren’t paying, you were out.

The timing was terrible. LocalStack Community had become infrastructure for countless CI pipelines, dev environments, and tutorials. Overnight, teams had to choose: pay up, rip it out, or find something else.

Floci is that something else — and it’s better than what we lost.

What Is Floci?

Floci is a free, open-source local AWS emulator. MIT licensed. No auth tokens. No feature gates. No paid tiers. You pull a Docker image, point your AWS SDK at localhost:4566, and you’ve got AWS running on your laptop.

Sound familiar? It should. Floci is a drop-in replacement for LocalStack Community. Same port, same API surface, same CLI calls. Swap the Docker image and you’re done.

But Floci isn’t just a clone. It’s a ground-up rewrite that’s faster, lighter, and covers more services than LocalStack Community ever did.

Performance: Not Even Close

Here’s the comparison that matters:

Metric	LocalStack Community	Floci
Startup time	~3.3 seconds	~24 milliseconds
Idle memory	~143 MB	~13 MB
Docker image	~1 GB	~90 MB

Floci starts 137× faster and uses 11× less memory. On a MacBook Air, you barely notice it’s running. In CI, those seconds and megabytes add up across hundreds of pipeline runs per day.

Real Docker Integration, Not Just Mocks

This is where Floci diverges from the LocalStack philosophy. Instead of mocking everything in Python, Floci spins up real backing services inside Docker:

• RDS → actual Postgres or MySQL containers
• ElastiCache → real Redis or Valkey instances
• MSK → Redpanda (Kafka-compatible)
• EKS → k3s clusters
• Athena → DuckDB for SQL queries
• EC2 → real Docker containers with SSH access
• Lambda → AWS ECR runtime images, not shims

When you create an RDS instance in Floci, you get a real Postgres database you can connect to with psql. When you launch an EC2 instance, you get a Docker container you can SSH into. This means your local tests exercise the same database drivers, connection logic, and query behavior as production.

Services LocalStack Never Had

LocalStack Community’s service coverage was always limited. Floci fills the gaps with services the free tier never offered:

• Cognito — user pools, identity pools, full auth flows
• RDS — real database instances, not stubs
• ElastiCache — Redis/Valkey clusters
• ECS & EKS — container orchestration with real containers
• EC2 — Docker-backed instances with networking and SSH
• MSK — Kafka via Redpanda
• Athena — SQL analytics via DuckDB
• CodeBuild & CodeDeploy — CI/CD service emulation
• API Gateway v2 — WebSocket and HTTP APIs
• Auto Scaling, Transfer Family, and more

Plus all the staples: S3, DynamoDB, SQS, SNS, Lambda, IAM, STS, KMS, Step Functions, CloudFormation, EventBridge, CloudWatch, Secrets Manager, and SSM.

Architecture

Floci organizes services into three tiers:

1. Stateless services (IAM, STS, KMS) — pure in-memory, instant responses
2. Stateful services (S3, DynamoDB, SQS) — configurable storage backends
3. Container services (RDS, ECS, EKS, EC2) — spin up real Docker containers on demand

Storage backends are pluggable: memory (fastest, ephemeral), hybrid (memory + disk spillover), persistent (survives restarts), or WAL (write-ahead log for durability without performance loss). Pick what fits your workflow.

Migrating from LocalStack

The migration path is deliberately painless:

# Before (LocalStack)
services:
  localstack:
    image: localstack/localstack
    ports:
      - "4566:4566"

# After (Floci)
services:
  floci:
    image: ghcr.io/floci-io/floci
    ports:
      - "4566:4566"

That’s it. Same port, same endpoint. Your AWS SDK and CLI calls don’t change. Floci even auto-translates LocalStack environment variables — LOCALSTACK_API_KEY, SERVICES, DEBUG — so you don’t need to rewrite your docker-compose files from scratch.

The Bottom Line

LocalStack Community served the community well for years. Its sunset left a real gap. Floci fills it with something that’s not just free, but genuinely better: faster startup, smaller footprint, real service backends, and broader coverage.

It’s MIT licensed and on GitHub. No auth tokens. No feature gates. No rug-pull clause. Free forever.

docker run -d -p 4566:4566 ghcr.io/floci-io/floci

That’s your local AWS. Twenty-four milliseconds from now.