fakecloud
Local AWS cloud emulator. Free forever.

fakecloud is a free, open-source local AWS emulator for integration testing and local development. Single binary, no account, no auth token, no paid tier. Point your AWS SDK at http://localhost:4566 and it works.

In March 2026, LocalStack replaced its open-source Community Edition with a proprietary image that requires an account and auth token. fakecloud exists so teams can keep a fully local AWS testing workflow without one.

[!NOTE] Using fakecloud? Add your team to ADOPTERS.md. Takes 30 seconds, and it helps others see it is real.

Quick start

curl -fsSL https://fakecloud.dev/install.sh | bash   # or: brew install fakecloud
fakecloud

Then point any AWS SDK or CLI at http://localhost:4566 with dummy credentials:

aws --endpoint-url http://localhost:4566 sqs create-queue --queue-name my-queue

Works as a drop-in for LocalStack in CI, with Terraform (endpoints block), CDK (cdklocal), or any AWS SDK in any language. Other install options (Homebrew, Cargo, Docker, Docker Compose, source) and full guides: fakecloud.dev/docs/getting-started.

Why fakecloud

• Free, forever. AGPL-3.0, no paid tier, no account, no token.
• True 100% conformance. 248,319 Smithy-model-generated test variants pass on every commit, validated against AWS's own Smithy models. CI also runs upstream terraform-provider-aws TestAcc* suites to catch waiter/field/drift bugs that SDK tests miss.
• Real cross-service wiring. EventBridge -> Step Functions, S3 -> Lambda, SES inbound -> S3/SNS/Lambda, and 15+ more integrations execute end-to-end.
• Real infrastructure for stateful services. Lambda (23 runtimes), RDS (Postgres/MySQL/MariaDB/Oracle/SQL Server/Db2), ElastiCache (Redis/Valkey/Memcached), ECS, and EC2 run as real containers. Use Docker (default) or native Kubernetes Pods via FAKECLOUD_CONTAINER_BACKEND=k8s. See the Kubernetes backend guide.
• Single binary. ~19 MB, ~10 MiB idle, ~300ms startup. No Docker needed to run fakecloud itself.
• Full Bedrock surface. 216 ops across 4 APIs with real InvokeModel/Converse streaming, guardrails, agents, and flows. Configurable responses + fault injection for deterministic tests. See /bedrock-emulator/.
• First-party test SDKs for TypeScript, Python, Go, PHP, Java, and Rust. Assert on what your code called without raw HTTP.
• Opt-in SigV4 verification and IAM enforcement. Off by default so tests just work; --verify-sigv4 for real signature checking and --iam soft|strict for policy evaluation across IAM/STS/SQS/SNS/S3. See security docs.
• Run your app unmodified. An app that expects an instance/task role resolves the AWS SDK default credential chain against fakecloud with no static keys and no code change: point AWS_CONTAINER_CREDENTIALS_FULL_URI at /_fakecloud/credentials. See Run an app unmodified.
• LocalStack and real-AWS URL compatibility. Both *.localhost.localstack.cloud and *.amazonaws.com Host headers route correctly, including every S3 virtual-hosted variant. Persisted URLs and dev scripts from either system replay unchanged.

Supported services

105 services, 7,396 operations, and true 100% conformance across every implemented service.

Highlights: S3, DynamoDB, SQS, SNS, EventBridge, Lambda, IAM, STS, KMS, Secrets Manager, CloudFormation, SES, Cognito, Kinesis, RDS (6 real engines), ElastiCache, ECS/ECR, EC2, Step Functions, API Gateway v1/v2, Bedrock, and 80+ more.

Full list with per-service op counts, control-plane vs data-plane coverage, and known limitations:

• Parity matrix: fakecloud.dev/docs/parity
• Per-service docs: fakecloud.dev/docs/services

Compared to LocalStack Community

Since March 2026, LocalStack's Community image requires an account and token, and most services are paid-only. fakecloud stays fully free and local.

Full feature-by-feature comparison: fakecloud.dev/vs/localstack.

Performance numbers measured on Apple M1 via time fakecloud, ps -o rss, ls -lh.

First-party SDKs

Normal AWS SDKs handle your application code. fakecloud's own SDKs let your tests assert on what happened: sent emails, SNS messages, Lambda invocations, Bedrock calls, and more.

import { FakeCloud } from "fakecloud";

const fc = new FakeCloud();

// Your app sends through the normal AWS SDK.
// Your test asserts the side effect directly.
const { emails } = await fc.ses.getEmails();
expect(emails).toHaveLength(1);

await fc.reset();

Full SDK reference for all seven languages: fakecloud.dev/docs/sdks.

Use with AI coding tools

Add one of these snippets to your project so AI coding assistants (Claude Code, Cursor, GitHub Copilot) automatically use fakecloud for AWS integration tests.

## AWS Testing

For integration tests, use fakecloud as a local AWS emulator.

- Install: `curl -fsSL https://fakecloud.dev/install.sh | bash`
- Run: `fakecloud` (listens on http://localhost:4566)
- Configure AWS SDK endpoint to http://localhost:4566 with dummy credentials (access_key=test, secret_key=test)
- Docs: https://fakecloud.dev/llms.txt

For AWS integration tests, use fakecloud (local AWS emulator) at http://localhost:4566.
Install: curl -fsSL https://fakecloud.dev/install.sh | bash
Run: fakecloud
Use dummy credentials (access_key=test, secret_key=test).
Docs: https://fakecloud.dev/llms.txt

## AWS Testing

Use fakecloud as a local AWS emulator for integration tests.

- Run: `fakecloud` (listens on http://localhost:4566)
- Configure endpoint_url to http://localhost:4566 with dummy credentials
- Docs: https://fakecloud.dev/llms.txt

Docs and guides

• fakecloud.dev — website
• Getting started — install, first test, SDK setup
• Guides — in-depth how-tos (testing Bedrock, cross-service integration, CI setup)
• Reference — configuration, introspection endpoints, persistence, image signature verification
• Blog — essays and hot takes on testing, AWS, and AI-assisted development

Who's using fakecloud

See the current list in ADOPTERS.md. It is early days, so it is short for now.

Using fakecloud? Add your team: the preferred way is a quick PR adding a row to ADOPTERS.md. If a PR is inconvenient, comment on the "Who's using fakecloud?" issue instead. Self-reported and opt-in.

Contributing

Contributions welcome. Fork, branch, write tests, open a PR.

• Conventional commits (feat:, fix:, chore:, test:, refactor:)
• E2E tests for every new action
• cargo test --workspace && cargo clippy --workspace -- -D warnings && cargo fmt --check

See CONTRIBUTING.md for more.

License

fakecloud is free and open-source, licensed under AGPL-3.0-or-later. Using fakecloud as a dev/test dependency has zero AGPL implications for your application — the copyleft clause only applies if you modify and redistribute fakecloud itself as a network service.

Part of the faisca project family | fakecloud.dev