Is AWS Emulator free and open source?

AWS Emulator has no service fee and needs no AWS account; you pay only for real AWS resources when you deploy. The source code is on GitHub at aws/aws-emulator under the CC0-1.0 public-domain dedication, except the vendor/ directory, which is Apache-2.0. The repository takes bug reports through GitHub Issues but does not accept pull requests.

Can AWS Emulator test IAM permissions?

No. AWS Emulator does not evaluate IAM policies or resource-based policies the way AWS does, so a request that AWS would deny can succeed locally, and AWS says not to use it for security testing. It also keeps one account and does not separate resources by Region; to test several Regions, AWS suggests one emulator per Region on its own port.

How do I run AWS Emulator on macOS or Windows?

On macOS and Windows, AWS Emulator runs in Docker from an image you build with the short Dockerfile in the AWS documentation; AWS does not publish a ready-made image. On Linux it installs as an RPM or Debian package for x86_64 or aarch64. Rust projects using the AWS SDK for Rust can also embed it in the test process with the aws-emulator-embedded crate.

What happens when AWS Emulator does not support an API?

When AWS Emulator gets a call to an operation it has not implemented, it returns HTTP 501 Not Implemented, so the test fails right away instead of passing silently. AWS publishes a fidelity score for each service with every GitHub release, and the repository lists known gaps in an issues/things-that-do-not-work folder.

Did humans review the AWS Emulator code?

No, according to Amazon. Senior principal engineer Matthew Goldberg writes that the team has not written or reviewed any of AWS Emulator's code. Agents check coding standards and security at an automated merge gate, and changes that fail go back for rework. The project began as a weekend experiment in which Kiro built a first version of Amazon SQS in about 15 minutes.

Amazon Web Services · 2026-11-11 · major

AWS Emulator — a free local copy of the AWS APIs, built by AI agents

In short

AWS Emulator is a free, CC0-licensed Rust program that answers AWS CLI and SDK calls on your own machine, with no AWS account. AWS says AI agents wrote all of its code and its engineers did not review it.

Amazon Web Services · 2026-11-11 · 5 sources checked

AWS News Blog header for the AWS Emulator launch post

Point the AWS CLI or an SDK at a local endpoint and test against emulated AWS services without an account.

Key specs

Hn points	484

Quick facts

Maker	Amazon Web Services
License	CC0-1.0 (vendor/ code Apache-2.0)
Language	Rust
Price	No service fee, no AWS account needed
Runs on	Linux (RPM/DEB), Docker on macOS and Windows, embedded in Rust tests
Endpoint	HTTPS on 127.0.0.1:9297

What is it?

AWS Emulator is a local emulator of the AWS APIs that AWS released on November 11, 2026. You start it on your laptop, a dev server or a CI runner, set a few environment variables, and your existing AWS CLI commands and SDK code talk to emulated S3 buckets, DynamoDB tables and other resources instead of real ones. It has no GUI and no service fee.

How does it work?

The emulator serves one HTTPS endpoint for all services, checks SigV4 signatures with keys it generates on each start, and keeps every resource in memory until it stops. Amazon says three teams of AI agents built it from the AWS API models: test writers verify scenarios against real AWS, issue finders replay those fidelity tests against the emulator, and fixers merge one fix per issue through an automated gate for build, review, security and fidelity.

Why does it matter?

Integration tests and coding agents can now exercise AWS code paths with no credentials and no cloud bill, so an agent cannot touch a real account by mistake. The project is also a public test of agent-written infrastructure software: AWS publishes per-service fidelity scores with each release and keeps the failing tests in an open evaluation suite.

Who is it for?

AWS developers, CI pipelines and AI coding agents

Frequently asked questions

Is AWS Emulator free and open source?: AWS Emulator has no service fee and needs no AWS account; you pay only for real AWS resources when you deploy. The source code is on GitHub at aws/aws-emulator under the CC0-1.0 public-domain dedication, except the vendor/ directory, which is Apache-2.0. The repository takes bug reports through GitHub Issues but does not accept pull requests.
Can AWS Emulator test IAM permissions?: No. AWS Emulator does not evaluate IAM policies or resource-based policies the way AWS does, so a request that AWS would deny can succeed locally, and AWS says not to use it for security testing. It also keeps one account and does not separate resources by Region; to test several Regions, AWS suggests one emulator per Region on its own port.
How do I run AWS Emulator on macOS or Windows?: On macOS and Windows, AWS Emulator runs in Docker from an image you build with the short Dockerfile in the AWS documentation; AWS does not publish a ready-made image. On Linux it installs as an RPM or Debian package for x86_64 or aarch64. Rust projects using the AWS SDK for Rust can also embed it in the test process with the aws-emulator-embedded crate.
What happens when AWS Emulator does not support an API?: When AWS Emulator gets a call to an operation it has not implemented, it returns HTTP 501 Not Implemented, so the test fails right away instead of passing silently. AWS publishes a fidelity score for each service with every GitHub release, and the repository lists known gaps in an issues/things-that-do-not-work folder.
Did humans review the AWS Emulator code?: No, according to Amazon. Senior principal engineer Matthew Goldberg writes that the team has not written or reviewed any of AWS Emulator's code. Agents check coding standards and security at an automated merge gate, and changes that fail go back for rework. The project began as a weekend experiment in which Kiro built a first version of Amazon SQS in about 15 minutes.

Try it

aws agent-toolkit add-skill --skill-name aws-emulator --region us-east-1