CloudMock runs 100 AWS services on your machine. Same SDKs, same APIs, same behavior. No account, no cost, no network. Your tests work offline and finish in milliseconds.
How it works
CloudMock emulates AWS locally. Your code talks to localhost:4566 instead of real AWS. Same SDK calls, same responses, same error codes. Nothing to configure.
One command. No dependencies, no Docker, no cloud account.
npx cloudmock Override the endpoint in your AWS SDK config.
const client = new S3Client({
endpoint:
"http://localhost:4566",
}); Inspect services, trace requests, and test failure scenarios in the browser.
http://localhost:4500 Performance
Verified benchmarks. Endpoint-fingerprinted. Rust-accelerated DynamoDB. Measured with hey on real HTTP requests.
Geometric mean across 8 core AWS operations
LocalStack: 457 req/s (Docker + Python)
Moto: 795 req/s (Python + Flask)
5,000 SDK calls in 0.1s vs 23s on LocalStack
ROI
23 seconds saved per build × 1,000 builds/day = 6.4 hours of developer wait time eliminated every day. That's 1.1 engineer-years saved annually.
Why CloudMock
100 fully emulated AWS services -- S3, DynamoDB, SQS, Lambda, IAM, EC2, ECS, RDS, and 91 more. Zero stubs. Test your integrations without an AWS account.
See every request, trace it across services, inspect payloads, view topology maps, track metrics, and inject failures. All at localhost:4500 -- no extra setup.
Go, Python, Node.js, Java, Kotlin, Rust, C/C++, Ruby, C#, and Swift. Use your existing AWS SDK -- just change the endpoint.
Full policy evaluation, credential verification, or no-auth mode. Test your IAM policies locally before deploying.
Inject failures, latency, and errors to test your application's resilience before it hits production.
Export state to JSON, commit to version control, and restore on startup. Every developer starts with the same pre-configured resources — no setup scripts needed.
Works out of the box. No Docker required. No cloud account. No YAML files. Start building in seconds.
Services
100 fully emulated AWS services with proper error codes, pagination, state machines, and resource relationships. Zero stubs.
Coming Soon
Install a lightweight agent. See your production AWS topology, traces, and metrics in the same devtools you already use for local development. One UI for local and production.
The topology, traces, and metrics views you already know -- now showing your real AWS infrastructure. Zero learning curve.
Go SDK middleware or reverse proxy sidecar. 5MB binary, zero config. Set one env var and you're collecting data.
$10/seat/month + $0.50 per million events. Compare local vs production latency side by side. No per-host pricing.
Source Available
CloudMock is source-available under the Business Source License. Use it locally, host it internally, run it in CI -- no limits. Converts to Apache 2.0 on April 1, 2030.