Floci is a free, MIT-licensed, open-source local AWS emulator that gives developers, testers, and CI pipelines AWS-shaped services on their own machine without a cloud account, an auth token, or paid feature gates.

What it is

Floci is a Java-based emulator written for the AWS ecosystem. It runs AWS services locally and exposes them at http://localhost:4566, where any AWS SDK, the AWS CLI, Terraform, CDK, OpenTofu, or a test suite can point at it and keep working unchanged. Any region is accepted, and credentials may be any non-empty values unless stricter service-specific auth checks are explicitly enabled. It is the AWS member of the wider Floci emulator family, alongside floci-az for Azure on port 4577, floci-gcp for GCP on port 4588, and floci-oci for OCI on port 4599. The name comes from floccus, the cloud formation that looks like popcorn.

The concrete thing it replaces is LocalStack. Floci is documented as a drop-in replacement for it: an existing LocalStack setup can swap the container image and continue, which is the specific migration the project targets. It removes the need for a hosted or account-bound emulation service in local development and continuous integration, and it removes the feature gates and auth-token requirement that a developer would otherwise hit before running the first aws s3 mb command.

Key capabilities

• Serves AWS service endpoints on a single port, http://localhost:4566, with the covered service set including EC2, ECS, S3, SQS, and DynamoDB among the repository topics and README examples.
• Acts as a drop-in LocalStack replacement, so migration is an image swap rather than a rewrite of test or application configuration.
• Ships a CLI with floci start to launch the emulator and floci env to export the local AWS environment variables into a shell.
• Publishes an official container image, floci/floci:latest, runnable from a minimal compose.yaml that maps port 4566.
• Provides a browser web console at http://localhost:4566/_floci/ui for inspecting resources in the running emulator.
• Runs the console as a sidecar container (floci/floci-ui:latest by default) configured through FLOCI_SERVICES_UI_ENABLED, FLOCI_SERVICES_UI_IMAGE, FLOCI_SERVICES_UI_CONTAINER_NAME, FLOCI_SERVICES_UI_PORT (default 4500), and FLOCI_SERVICES_UI_KEEP_RUNNING_ON_SHUTDOWN.
• Supports a documented console contract, so any console implementing it can be substituted by supplying an image name and listening on the port given in PORT.

Who uses it and how

• Developers who want AWS behaviour on a laptop without a cloud account, an auth token, or network access to a real region.
• CI pipelines that need emulated AWS services in a container rather than credentials and a billed account.
• Teams already on LocalStack that want the same workflows with a self-hosted, MIT-licensed emulator and an image-name change.
• Infrastructure-as-code users testing Terraform, CDK, or OpenTofu plans against endpoints on http://localhost:4566.
• Test-suite authors using Testcontainers to bring emulated AWS services up alongside application tests, as the topic list indicates.
• Users of the sibling emulators who want one consistent local cloud story across AWS, Azure, GCP, and OCI.

Getting started

The fastest route is the official CLI: run floci start, then eval $(floci env) to export the environment. Alternatively, deploy the floci/floci:latest image with docker compose up from a compose.yaml that maps 4566:4566, and set AWS_ENDPOINT_URL, AWS_DEFAULT_REGION, AWS_ACCESS_KEY_ID, and AWS_SECRET_ACCESS_KEY manually.

How it compares

The facts name LocalStack as the product Floci replaces. Floci is licensed under MIT, is self-hosted by definition since it runs on the developer's own machine, and documents itself as free with no account, no auth token, and no paid feature gates, so all emulated resources stay local and no data leaves the host. LocalStack is the incumbent being displaced, and Floci's stated advantage over it is that same free, ungated, drop-in behaviour rather than a different API surface.

When to use it — and when not

A self-hoster must run a Docker daemon, and enabling the web console additionally requires mounting /var/run/docker.sock, which grants the container control of the host Docker daemon. Anyone uncomfortable with that should set FLOCI_SERVICES_UI_ENABLED to false or run without the console. Note also that the former hectorvent/floci image no longer receives updates, so configurations must use floci/floci:latest, and the repository carries 130 open issues, which is worth weighing before adopting it as a critical CI dependency.

floci start

eval $(floci env)

aws s3 mb s3://my-bucket

aws dynamodb create-table \
  --table-name demo-table \
  --attribute-definitions AttributeName=pk,AttributeType=S \
  --key-schema AttributeName=pk,KeyType=HASH \
  --billing-mode PAY_PER_REQUEST

aws dynamodb list-tables

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

docker compose up

export AWS_ENDPOINT_URL=http://localhost:4566
export AWS_DEFAULT_REGION=us-east-1
export AWS_ACCESS_KEY_ID=test
export AWS_SECRET_ACCESS_KEY=test

# Before
image: hectorvent/floci:latest

# After
image: floci/floci:latest

services:
  floci:
    image: floci/floci:latest
    ports:
      - "4566:4566"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock

environment:
  FLOCI_SERVICES_UI_IMAGE: acme/my-console:1.0

environment:
  FLOCI_SERVICES_UI_IMAGE: davireis/stackport:latest
  FLOCI_SERVICES_UI_CONTAINER_NAME: floci-stackport
  FLOCI_SERVICES_UI_PORT: "8080"
  FLOCI_SERVICES_UI_INTERNAL_PORT: "8080"

environment:
  FLOCI_SERVICES_UI_IMAGE: ghcr.io/ofsazib/floci-dash:latest
  FLOCI_SERVICES_UI_CONTAINER_NAME: floci-dash
  FLOCI_SERVICES_UI_ENDPOINT_ENV: FLOCI_URL
  FLOCI_SERVICES_UI_STATUS_PATH: /api/healthz