MiniStack. The best alternative to LocalStack.

We built a free, open-source alternative to LocalStack — and it supports EMR for free

LocalStack is great software. But over time, more and more services moved behind a paid Pro tier — including EMR, EC2, Cognito, and others. For teams running CI/CD pipelines or local dev environments, the cost adds up fast.

So we built MiniStack. The best alternative to LocalStack. .

MiniStack is a pure-Python AWS emulator that runs on a single port (4566), starts in under 2 seconds, and requires zero configuration. No Docker daemon required for core services. MIT licensed, no account needed.

What's supported today:

| Category | Services |

|---|---|

| Storage | S3 (path + virtual-hosted style), DynamoDB |

| Messaging | SQS, SNS, Kinesis, Firehose, EventBridge |

| Compute | Lambda (real Docker containers), ECS, EC2 |

| Data | EMR, Glue, Athena (DuckDB-backed) |

| Database | RDS, ElastiCache |

| Auth | IAM, STS, Cognito (User Pools + Identity Pools) |

| API | API Gateway v1 + v2 |

| Ops | CloudWatch, CloudWatch Logs, Secrets Manager, SSM, SES, Step Functions, Route53 |https://ministack.orghttps://github.com/nahuel990/ministack

We just shipped MiniStack v1.1.0. This is the biggest release since the initial launch — full Amazon Cognito support, a complete test suite overhaul, and a pile of infrastructure fixes that make running MiniStack day-to-day significantly cleaner.

If you're not familiar: MiniStack is a free, open-source local AWS emulator. One port, no account, no license key. A drop-in replacement for LocalStack — which moved its core services behind a paid plan.

This was the most requested feature since launch. v1.1.0 ships complete Cognito support across both planes:

User Pools (cognito-idp)

Identity Pools (cognito-identity)

OAuth2

Stub JWTs are structurally valid base64url tokens — they pass format checks in most SDKs without needing real crypto.

We merged a separate QA test file into the main suite and fixed every test bug we found along the way:

613 tests across all 25 services. Single file. All passing.

This one was subtle. Every RDS (CreateDBInstance) and ElastiCache (CreateCacheCluster) call spins up a real Docker container. The postgres and mysql images declare VOLUME /var/lib/postgresql/data — so Docker was creating an anonymous volume for every container, even after the container was removed.

After 20 test runs: 30+ dangling volumes, 600MB+ of wasted space.

Two fixes:

Clean up what you already have:

Every container MiniStack spins up is labelled ministack=true. The purge target uses that label — it won't touch your other Redis, Postgres, or MySQL containers.

A user reported credentials failing. The README was showing aws configure --profile local but then omitting --profile local from the example commands. Fixed — two working options now documented:

Option A — environment variables

Option B — named profile

GitHub: github.com/Nahuel990/ministack

25 AWS services. Free. MIT licensed. No account required.

Issues and PRs welcome.

LocalStack archived its GitHub repo in March 2026 and now requires an auth token for every image pull. The free Community Edition is gone. If your CI depends on docker pull localstack/localstack without credentials, it's already broken.

After evaluating the alternatives, @MiniStack — Free Local AWS Emulator stood out for one reason: it runs real infrastructure, not mocks.

MiniStack vs @LocalStack

LocalStack moved to BSL licensing and mandatory accounts. The Community Edition is frozen — no security patches, no updates. CI credits are gated by pricing tier.

MiniStack. The best alternative to LocalStack. — Free Local AWS Emulator is MIT licensed. No account, no API key, no telemetry. Same port (4566), same endpoint format. Drop-in swap:

docker run -p 4566:4566 nahuelnucera/ministack

Image is ~150 MB vs LocalStack's ~1 GB. Idles at ~30 MB RAM vs ~500 MB.

The Real Infrastructure Difference

Most AWS emulators fake everything in memory. MiniStack doesn't — not where it matters.

• RDS creates actual Postgres/MySQL Docker containers. Not a mock. A real database you can connect to with psql.

• ElastiCache spins up real Redis containers with IAM auth support.

• ECS runs real Docker containers.

• Athena executes real SQL via DuckDB.

• Lambda runs real Python with warm starts between invocations.

No other free emulator does this. @LocalStack had real databases only in Pro. @Floci and @Moto fake it in memory.

vs @Floci

@Floci is fast and lightweight (~90 MB image, ~13 MB idle RAM, 24ms startup). Solid for quick CI emulation. But everything is in-memory. If integration tests need actual database connections, actual Redis commands, actual container execution — MiniStack is the better fit.

vs @Moto

@Moto is the gold standard for Python unit tests — in-process, no Docker, fast. Right tool for mocking boto3 calls. But it doesn't run a service or provide real endpoints. If tests need actual network calls or work across languages beyond Python, MiniStack fills that gap.

21 Services, One Port

S3, SQS, SNS, DynamoDB, Lambda, RDS, ElastiCache, ECS, Athena, IAM, STS, Secrets Manager, SSM Parameter Store, EventBridge, Kinesis, CloudWatch Logs, CloudWatch Metrics, SES, Step Functions, Glue.

Works with boto3, @AWS CLI, @Terraform, @AWS CDK, @Pulumi — any tool that speaks the AWS API.

Bottom Line

If you need a free, MIT-licensed, drop-in LocalStack replacement that spins up real databases and real containers instead of faking it — MiniStack is it.

GitHub: https://github.com/Nahuel990/ministack

Docker Hub: nahuelnucera/ministack

Website: https://ministack.org