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AWS Emulator

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Intro

AWS Emulator is the local emulator Amazon Web Services announced as generally available on November 11, 2026, in the official news blog Test your applications against AWS locally with AWS Emulator, by Daniel Abib. The post begins: “Today we’re announcing AWS Emulator, a local emulator for Amazon Web Services (AWS) that you run on your machine.” The AWS CLI, the AWS SDKs, and coding agents speak to it over a local HTTPS endpoint using the same AWS APIs they would use in the cloud. The product page is AWS Emulator, the docs are at docs.aws.amazon.com/emulator, and the source repository is github.com/aws/aws-emulator.

Officially, AWS Emulator has no additional service fee; you pay only for AWS resources when you deploy on AWS. You install it from an RPM or Debian package on Linux (the package adds the aws-emulator command to /usr/bin/), and on macOS and Windows you build a Docker image from the short Dockerfile in the documentation and run it in a container; AWS says it does not publish a ready-made image. When it starts, it serves HTTPS on 127.0.0.1:9297 and writes credentials, a config file, and a certificate to ~/.aws/emulator/9297/. Access key IDs start with EMULATOR, and it rejects requests signed with any other keys. The emulator uses a single account, 000000000000. It is implemented in Rust. It supports the APIs of AWS services that have an API model in the AWS API models repository on GitHub, so requests and errors have the same shape as on AWS. For tests, there is also an embedded mode (aws-emulator-embedded crate, for the AWS SDK for Rust) that you instantiate inside the test process; each embedded instance keeps its own state, so tests can run in parallel. Operations that are not implemented yet return HTTP 501.

On fidelity, the official blog measures the emulator with fidelity tests: short SDK workflows are first verified against real AWS, and a test passes only if the emulator matches AWS on the status code, body, and exact error code and message of every call, and on the resources and data the workflow creates. Each release publishes how many tests pass per service, as k of n. The set, including tests that do not pass yet, is public in aws-emulator-evaluation-suite. The blog notes that a score can go down when new tests are added, even while the emulator improves. On how it is built, the blog says AWS Emulator is built and maintained by agents from the AWS API models using Amazon Bedrock AgentCore Runtime Instances, AWS CodePipeline, and AWS CodeCommit. One group of agents looks for gaps by comparing emulator responses against real AWS and by statically comparing code against published Smithy models; another group writes tests, implements the behavior, and reviews the change for correctness, performance, and security before a pipeline run. Because the code is written by agents, an independent security agent reviews changes adversarially while a fix is being made and again in the release pipeline. Amazon’s official news post How we built the agents that built AWS Emulator (Matthew Goldberg, November 11, 2026) says the team has not written or reviewed any of the code, that the source is released under Creative Commons CC0, and that issues live in issues/things-that-now-work and issues/things-that-do-not-work. Amazon CTO Werner Vogels posted at 2026-11-11T18:02:21Z that “AWS Emulator, launched today and written and tested entirely by agents, gives you that kind of environment for more than 200 AWS services,” and linked to the guest post at https://www.allthingsdistributed.com/2026/11/aws-emulator-and-the-engineers-job-when-agents-write-the-code.html .

On limits, the official blog says the emulator does not evaluate IAM policies and resource-based policies the way AWS does, so a request that AWS denies might succeed in the emulator; each emulator acts as a single account, with no cross-account or cross-Region behavior; how closely it matches AWS varies by service and feature; you should not use it to test whether your application is secure, and you should keep real credentials out of test-job environments. By default it also sends anonymous usage and error data, which you can turn off.

Key points:

Explain

Why it matters

This is a formal product name AWS published as generally available on November 11, 2026, in an official news-blog launch, with a same-day post from Amazon’s CTO, not a rumor or an internal nickname. It turns “test against the same AWS APIs on a laptop or in CI” into a nameable tool, with public source and a public fidelity-test suite. For anyone tracking cloud developer tools and agent-written software, this is a new name that deserves its own entry.

This page only restates public official materials. Installation details, endpoint behavior, the definition of fidelity tests, Vogels’ “more than 200 AWS services,” and the aboutamazon description that agents wrote all of the code and that it is CC0 are official statements; this page does not independently reproduce or audit them.

Limits

AWS is explicit: the emulator does not evaluate IAM and resource-based policies the way AWS does; each instance is a single account with no cross-account or cross-Region behavior; coverage varies by service; unimplemented operations return 501. Do not use it to validate production security settings, and do not put real AWS credentials into test environments. Published fidelity scores are snapshots, not a guarantee of complete API behavior.

Usage

  1. Read the official blog at https://aws.amazon.com/blogs/aws/test-your-applications-against-aws-locally-with-aws-emulator/ , and compare it with the product page at https://aws.amazon.com/products/developer-tools/emulator/ , the docs at https://docs.aws.amazon.com/emulator/ , the source at https://github.com/aws/aws-emulator , Werner Vogels’ post at https://x.com/Werner/status/2120577888844148891 , and the Amazon news post at https://www.aboutamazon.com/news/aws/how-autonomous-ai-agents-built-aws-emulator ;
  2. Follow the official instructions to install an RPM or Debian package on Linux, or run it in Docker on macOS or Windows; point AWS CLI/SDK environment variables at https://127.0.0.1:9297 and the emulator-generated credentials, and do not mix in real AWS keys; fidelity tests are at https://github.com/aws/aws-emulator-evaluation-suite ;
  3. When you cite “more than 200 services,” “written entirely by agents,” CC0, fidelity scores, or IAM differences, attribute them to the 2026-11-11 official blog, the aboutamazon news post, or Vogels’ post, and re-check the upstream source;
  4. Do not describe AWS Emulator as LocalStack, as real AWS, or as an environment you can use to validate production security policy; this page only restates official materials, so re-check the upstream source before you cite it elsewhere.

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