AWS Emulator is a free, open-source tool from Amazon that runs local copies of AWS services on your own computer. You point the AWS CLI or an SDK at localhost and test your app without touching the real cloud. Amazon released it on 11 November 2026.
What is AWS Emulator?
AWS Emulator is a local emulator of AWS services. You run it on your machine to build and test AWS applications (Amazon).
Quick facts:
- Price: free to use. Source is released under a CC0 public-domain dedication (SiliconANGLE).
- Coverage: built from 438 AWS API models, covering more than 200 services (Unite.AI).
- Language: Rust (SiliconANGLE).
- Runs on: Linux, Windows, macOS, or as a Docker container. Linux gets an RPM or Debian package — install it and run
aws-emulator. On Windows and macOS, run it in a container built from a short Dockerfile (GitHub README). - Account needed: none. The README says it plainly: “You don’t need an AWS account. Your requests go to the emulator, not to AWS.” (GitHub README).
Why Amazon built it
AI coding agents such as Kiro and Claude Code write code fast. Checking that code against the real cloud is slow and costs money. A local emulator lets you run the test loop again and again on your own machine (SiliconANGLE).
How it was built
It began as a weekend experiment at AWS. The approach was test-first: write tests based on the AWS CLI, iterate on them until they pass against real AWS, then build a local in-memory implementation that passes the same tests. The first result — a working SQS emulator — came together in about 15 minutes (About Amazon).
Today, three teams maintain it:
| Team | Job |
|---|---|
| Test team | Writes fidelity tests from public AWS API models and checks each one against real AWS |
| Finder team | Replays the tests on the emulator and files issues for failures |
| Fixer team | Takes one issue, fixes the code, and passes a merge gate (build, coding standards, security, no fidelity regression) |
The result is checked by strict guardrails — mainly the tests and the merge gate (About Amazon).
How to use it
The idea is simple: start the emulator, then redirect your AWS CLI or SDK calls to localhost (SiliconANGLE).
- Get it from the official repo: https://github.com/aws/aws-emulator. On Linux, install the RPM or Debian package; on Windows or macOS, use the Docker path. If you use an AI coding agent, install the aws-emulator skill instead:
aws agent-toolkit add-skill --skill-name aws-emulator --region us-east-1(needs AWS CLI 2.35.0 or later). - Start the local server with
aws-emulator. It serves HTTPS on 127.0.0.1:9297 (self-signed certificate). - Set your AWS CLI or SDK endpoint to that local address.
- Run your tests. Valid calls should behave like the cloud.
Limits you should know
- Not a security test. Do not use it to check whether your IAM policies block the right requests. A request that real AWS would deny might succeed locally, and the README says it directly: “Don’t use it for production workloads or to test security.” (GitHub README).
- Known gaps are public. Amazon publishes unfixed issues in the repository folder
issues/things-that-do-not-work. Fixed ones are inissues/things-that-now-work(About Amazon). - Not full AWS. Fidelity varies by service and feature — check the fidelity scores published with each release. Unsupported calls return a 501 “Not Implemented” response. It does not yet simulate throttling, outages, or regional differences in service availability (IDC analyst Devin Pratt, via GeekWire).
- Telemetry is on by default. The emulator reports usage data to AWS — but not your request or response contents, code, credentials, or personal data. Turn it off with
aws-emulator --telemetry offor by settingEMULATOR_TELEMETRY=off(GitHub README). - Read the repo first. The emulator is new — read the code before you trust it with sensitive work.
- Final check still belongs on real AWS. Use the emulator for fast loops, then deploy to a test account.
AWS Emulator vs other local AWS tools
Other local AWS emulators exist. SiliconANGLE says they cover only a small part of the AWS catalog and can drift out of sync as services change. The best-known one, LocalStack, put its free version behind an account requirement this year and limited it to noncommercial use — AWS Emulator has no account requirement and no paid tier (GeekWire).
FAQ
Yes. Amazon released it as free, open-source software under CC0. The README: “AWS Emulator has no additional service fee. You pay only for AWS resources when you deploy on AWS.”
No. The README says you don’t need an AWS account — your requests go to the emulator, not to AWS.
It is built from 438 API models covering more than 200 services. Coverage depth differs by service.
Do not rely on it for that. The README says not to use it to test security, and a request real AWS would deny can succeed locally. Test security rules on real AWS.
Rust.
AWS Emulator is a useful free option for fast, offline test loops, especially if you build with AI coding agents. Treat it as a speed tool, not a final check. Test security and production behavior on real AWS.
By Aditya