Source: simonwillison.net/2026/Nov/11/aws-emulator
AWS has published aws-emulator, an official emulator for running tests against a local copy of its many services without provisioning a paid API key. Simon Willison describes it as written in Rust by a large swarm of agents, and cites 29,684 commits in the first three weeks of the project.
Swaminathan (Swami) Sivasubramanian explains how the project came about in a guest post on Werner Vogels' blog. Willison links to that post as the primary account of the project's origins.
The emulator currently requires Docker to run on macOS or Windows. Willison hopes a future version can be distributed as a single binary that works in standard test suites in other languages and on other platforms.
Why it matters if you build agents
Agent developers can run integration tests against AWS service behaviour locally, without making paid API calls during test runs. Teams on macOS or Windows will still need Docker in their test setup until the requirement is removed. Check which services the emulator covers before relying on it in place of real AWS endpoints.
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