floci: a free local AWS emulator that replaces LocalStack outright

Local development against AWS means either risking a real account or living inside LocalStack’s account, token and paywall. floci (MIT, 29,648 stars as of November 5, 2026) offers a third way: one docker compose up and your machine runs AWS-shaped services — no account, no auth token, no feature gates. Point your AWS SDK, CLI, Terraform, CDK, OpenTofu or test suite at http://localhost:4566 and keep every existing workflow. It is also a drop-in LocalStack replacement: swap the image name and continue.

Core features

• Zero-gate local cloud: no cloud account, no token; runs in CI, and test environments stay naturally separated from production configuration — no more fighting over a shared account’s concurrency limits.
• LocalStack drop-in: a dedicated migration guide — swap the image, keep the workflows.
• SDK-native: AWS SDK, CLI, Terraform, CDK, OpenTofu and Testcontainers all connect to port 4566 the usual way.
• A family: sibling projects include floci-az (a local Azure emulator) and floci-ui, a web console for the local cloud.

Typical use cases

• Integration tests: spin up S3/SQS-shaped services in CI without spend or external calls; every PR gets its own isolated instance.
• IaC rehearsals: validate Terraform/OpenTofu plans locally before touching the real account, avoiding plan-is-mutation accidents.
• Offline development: travel and air-gapped environments stop being blocked on cloud reachability.
• Testcontainers integration: the repo ships a Testcontainers section, so JVM test suites attach to port 4566 directly.

Quick start

docker compose up

Then point AWS endpoints at http://localhost:4566; LocalStack users can follow the repo’s Migrating section to swap images. Official Docker images publish as floci/floci, releases are built automatically by GitHub Actions with build badges attached, and upgrades can simply track the latest tag. A sibling floci-ui project adds a web console for inspecting whatever state your tests leave behind.

Summary

floci fits test and CI loops that frequently need AWS-shaped dependencies; teams needing the full service catalog or production-fidelity emulation details should still weigh LocalStack’s paid tiers. Facts and limits: MIT, Java implementation, 29,648 stars since the repo opened in February 2026, with official Docker images published as floci/floci; a local emulator does not reproduce real-cloud quotas, throttling and regional behavior, so load tests and cost estimates still belong on real AWS; check the Services section of the repo before migrating to confirm coverage of what you use. It rides the same trend as agent-autoloop on this site — capabilities that used to require the cloud are moving back onto your machine: autoloop pulls the always-running agent onto one box, floci pulls the development cloud into one container.