AWS released an official local cloud emulator today — free, open source under CC0, and built 100% by autonomous AI agents. The repository has 29,684 commits. The first was three weeks ago. AWS Emulator runs 200+ services on your laptop, dev server, or CI pipeline using the same CLI and SDK commands you already use against the real cloud. No new API surface to learn.
30,000 Commits in Three Weeks #
The story of how AWS Emulator was built is more interesting than the tool itself. Senior Principal Engineer Matt Goldberg gave the agent Kiro a single prompt. Fifteen minutes later, it returned a working SQS emulator. That was the proof of concept. What followed was three weeks of three agent teams running continuously on Amazon Bedrock AgentCore: one team writing fidelity tests from public AWS API models and verifying them against real AWS; one replaying those tests against the emulator and filing issues; one fixing a single issue per agent run. Hundreds of agents work simultaneously. Thousands of issues fixed per day. No human reviewed the production code.
Werner Vogels captured the implication in his post on All Things Distributed: “When agents write the code and check their own work, the engineer’s job is to give them room to work on their own and to build the specs, tests, and merge gates that decide when that work is correct.” AWS Emulator is what that thesis looks like in production.
What It Does #
AWS Emulator runs as a local HTTP server on port 2772. It supports 200+ AWS services through 400+ API models — S3, Lambda, DynamoDB, SQS, and most of what you are likely testing. All state is in memory; it disappears when the emulator stops. Two modes:
- Server mode — point any AWS SDK or CLI at localhost:2772 with an endpoint override. Works with any language.
- Embedded mode — Rust SDK only. Runs inside the test process with per-test isolated state. No shared buckets, no shared queues. Runs in parallel.
Getting started in server mode:
curl -fsSL https://aws.amazon.com/emulator/install.sh | sh
aws-emulator start
aws s3 mb s3://my-local-bucket --endpoint-url http://localhost:2772
aws dynamodb create-table --table-name MyTable \
--attribute-definitions AttributeName=pk,AttributeType=S \
--key-schema AttributeName=pk,KeyType=HASH \
--billing-mode PAY_PER_REQUEST \
--endpoint-url http://localhost:2772
Full setup: AWS Emulator documentation.
Why This Matters Right Now #
In March 2026, LocalStack archived its Community Edition — 64,000 GitHub stars — and moved core services to a paid plan at $39 to $89 per developer per month. Developers reacted poorly. Teams switched to Floci, Testcontainers, and hand-rolled mocks. When AWS Emulator launched yesterday, the first comment on Hacker News was “RIP LocalStack.” That is the market AWS walked into: developers who wanted a free, reliable local cloud and were annoyed they lost one. AWS provided it under CC0, no seat fees, permanently.
The Limitations #
AWS is transparent about where this falls short. Current fidelity is 56.5% of 42,937 test units — that number is public, the evaluation suite is on GitHub, and it updates with every release. Low-fidelity services will behave differently from real AWS, so check per-service scores before relying on them in CI.
More critically: IAM policies are not enforced. A request real AWS would deny might succeed in the emulator. AWS says explicitly — do not use this to test security. For everything else, it works. For permission boundary testing, use a real AWS account.
One more thing: telemetry is on by default. The emulator sends anonymous usage data to AWS. Disable it with --telemetry off or the EMULATOR_TELEMETRY=off environment variable.
The Takeaway #
AWS Emulator is a genuinely useful tool that is free today and will stay free. If you are testing AWS-dependent code locally or in CI, there is no longer a reason to pay for it. Download it, check fidelity scores for the services you need, disable telemetry if you care, and skip it for security testing. The LocalStack-shaped hole in developer tooling has been filled by the company that owns the cloud it was emulating.
The more interesting story is the 30,000 commits. AWS just demonstrated that agents can build, test, and maintain production infrastructure without human code review — not as a research paper, but as a shipped product. That is what the next five years of software development will look like. The Register has more context on the broader implications for the cloud industry.