fakecloud

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.

Quick start

curl -fsSL https://raw.githubusercontent.com/faiscadev/fakecloud/main/install.sh | bash
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

Other install options (Cargo, Docker, Docker Compose, source) are documented at fakecloud.dev/docs/getting-started.

Why fakecloud

• Free, forever. AGPL-3.0, no paid tier, no account, no token.
• 100% conformance per implemented service. Every operation validated against AWS's own Smithy models — 59,000+ generated test variants on every commit.
• Tested against upstream Terraform acceptance tests. CI runs hashicorp/terraform-provider-aws TestAcc* suites against fakecloud. Catches waiter/field-presence/drift bugs that pure SDK tests miss.
• Real cross-service wiring. EventBridge -> Step Functions, S3 -> Lambda, SES inbound -> S3/SNS/Lambda, and 15+ more integrations actually execute end-to-end.
• Real infrastructure for stateful services. Lambda runs in Docker containers (23 runtimes). RDS runs real Postgres/MySQL/MariaDB/Oracle/SQL Server/Db2. ElastiCache runs real Redis/Valkey/Memcached.
• Single binary. ~19 MB, ~10 MiB idle memory, ~500ms startup. No Docker required to run fakecloud itself (only to exercise the services that need real containers).
• Bedrock, the whole surface. 111 operations across runtime + full control plane: InvokeModel/Converse (with streaming), guardrails (real content evaluation + PII detection), custom model jobs, model import, inference profiles, provisioned throughput, async batch via S3, prompt management, agreements, automated reasoning. Configurable responses per prompt + fault injection for deterministic Bedrock tests. LocalStack's Ultimate-tier Bedrock covers 4 ops backed by Ollama; fakecloud is free and covers the full Bedrock shape. See /bedrock-emulator/.
• First-party test SDKs for TypeScript, Python, Go, PHP, Java, and Rust. Assert on what your code called without writing raw HTTP.
• Opt-in SigV4 verification and IAM enforcement. Off by default so tests just work; turn on --verify-sigv4 for real cryptographic signature checking and --iam soft|strict for identity-policy evaluation (Allow/Deny with Deny precedence, Action/Resource wildcards, user/group/role policies, Condition blocks with all 28 AWS operators against global keys like aws:username / aws:SourceIp / aws:CurrentTime, plus resource-based policies for S3 bucket, SNS topic, and Lambda function policies with AWS's cross-account combining semantics) across IAM, STS, SQS, SNS, and S3. See the security docs.
• LocalStack and real-AWS URL compatibility. Both *.localhost.localstack.cloud and *.amazonaws.com Host headers decode to service + region for routing, including every S3 virtual-hosted variant (<bucket>.s3.<region>.…, legacy <bucket>.s3.amazonaws.com with implicit us-east-1, and the older dash-separated <bucket>.s3-<region>.amazonaws.com). Persisted queue URLs, presigned URLs, webhook targets, and dev scripts from either system replay against fakecloud unchanged.

Supported services

33 services, 2,422 operations, 100% conformance per implemented service.

Per-service docs and feature matrices: fakecloud.dev/docs/services.

Common use cases

Full guides: fakecloud.dev/docs/guides.

Compared to LocalStack Community

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 six 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://raw.githubusercontent.com/faiscadev/fakecloud/main/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://raw.githubusercontent.com/faiscadev/fakecloud/main/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
• Blog — essays and hot takes on testing, AWS, and AI-assisted development

Verifying image signatures

Every published image (fakecloud, fakecloud-postgres, fakecloud-mysql, fakecloud-mariadb) is Trivy-scanned and cosign-signed via GitHub OIDC. Verify before pulling:

cosign verify ghcr.io/faiscadev/fakecloud:latest \
  --certificate-identity-regexp '^https://github\.com/faiscadev/fakecloud/' \
  --certificate-oidc-issuer       https://token.actions.githubusercontent.com

See security docs for details.

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