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Introducing floci: Local Cloud Emulators, Free Forever

floci brings AWS, Azure, and GCP to your laptop with zero accounts, zero tokens, and sub-second startup. Here's why we built it and what's next.

Why We Built floci

Every developer on a cloud-native team has burned the same afternoon: pushed a small change, waited for CI to spin up real infrastructure, hit an auth error on a resource that worked fine yesterday, filed a ticket, and waited.

The tooling exists to run cloud services locally, but the most popular option, LocalStack, moved key services behind a paid tier and requires an auth token even for basic S3 access. The alternative is mocking, which works until it doesn’t, and it always doesn’t in production.

We wanted a different answer: every AWS, Azure, and GCP service your team actually uses, running on your laptop, with no account, no billing alarm, no token rotation, no tiers. That’s floci.

What floci Is

floci is a suite of open-source, MIT-licensed cloud emulators built with Quarkus Native. Quarkus Native compiles to a standalone binary with no JVM warmup, which is why floci starts in 24 milliseconds and sits at 13 MiB at idle.

There are three products today:

  • floci: 47 AWS services on port 4566, S3-compatible, drop-in LocalStack replacement
  • floci-az: 10 Azure services (Blob, Queue, Table, Functions, App Configuration, Key Vault, Event Hubs, Service Bus, Cosmos DB, AKS) on port 4577
  • floci-gcp: Cloud Storage, Pub/Sub, Firestore, Datastore, Secret Manager, IAM, and Managed Kafka

All three require no cloud account, ship as a single Docker image, and carry an MIT license. Fork it, embed it, ship it in your product.

Drop-In LocalStack Replacement

If you’re already using LocalStack, the migration is one line in your docker-compose:

# before
image: localstack/localstack

# after
image: floci/floci:latest

floci listens on port 4566, the same default as LocalStack CE. Your existing aws-sdk, boto3, @aws-sdk/client-s3, and Terraform configurations work without modification. The difference: no LOCALSTACK_AUTH_TOKEN, no plan limits, and startup in 24ms instead of 6 seconds.

The floci Stack

One of the most useful compositions is floci + floci-duck: pair the S3 emulator with a DuckDB-powered sidecar and you get local AWS Athena. Upload a CSV or Parquet file to your local S3 bucket, then query it with standard SQL. No AWS account, no per-query charges, no data transfer.

services:
  floci:
    image: floci/floci:latest
    ports:
      - "4566:4566"

  floci-duck:
    image: floci/floci-duck:latest
    ports:
      - "3000:3000"
    depends_on:
      floci:
        condition: service_healthy

More on floci-duck in the next post.

What’s Next

Service coverage is expanding across all three clouds. The roadmap is public on GitHub, so open an issue with the service you need most.

floci is free, forever.