Software Engineer - AWS Emulator Team

As a Software Engineer on the AWS Emulator team, you’ll help expand and harden LocalStack’s AWS emulator by taking ownership of individual services and making them behave as closely as possible to real AWS.

The challenge is genuinely unusual: you’ll reimplement cloud services that you can only observe from the outside. Making a service “work” is one thing; matching AWS behavior — including edge cases and undocumented details — is a very different engineering problem.

We’re looking for someone who learns quickly, enjoys tackling unfamiliar problems, and can turn incomplete information into working solutions. You’ll have end-to-end ownership of your services, from investigating how they behave and deciding what needs to be built through implementation, testing, and ongoing improvements.

AI is a core part of how the team works. You’ll use modern AI coding and agentic tools to make development more efficient while maintaining the quality and reliability expected by LocalStack users. The role offers a clear path to broader service ownership and technical leadership as your scope grows.

What you will be working on/responsible for:

• Internalize services off moto. Independently take AWS services from moto-backed to fully first-party implementations, owning store design for persistence, full API operation coverage, and conformance to LocalStack conventions rather than transplanted moto code. Measured by services shipped and their size.

• Close parity gaps in owned services. Raise snapshot-test coverage against real AWS for the documented API surface for owned services, with a measurable reduction in parity defects reported from the field.

• Own services end-to-end after they ship. Act as first responder for their services: customer-reported parity bugs triaged and turned around within 5 days median, including those that surface through Terraform and CDK rather than direct API calls.

• Raise the team's testing floor. Contribute reusable test infrastructure (conformance harnesses, snapshot tooling, fixtures) that other engineers adopt for services they do not own.

• Grow visibly in scope. By month 12, be trusted to scope and sequence an internalization independently, from API-documentation analysis through to shipped provider, without needing the plan handed to them.

Experience we expect you to bring to the role:

• 3+ years of professional software engineering experience, with strong engineering fundamentals. We’re language-agnostic — prior Python experience is not required.

• Experience working from a written specification against a system you cannot see inside, such as public APIs, protocols, wire formats, parsers, compilers, SDKs, emulators, or reverse-engineering projects.

• A strong testing mindset — you use tests as a tool for understanding and designing systems, not just for checking finished code.

• Hands-on experience with AI coding and agentic development tools. We’re looking for more than basic Copilot usage: you should have used these tools substantially to build and ship real software and understand both their strengths and limitations.

• Fast learning and strong problem-solving skills, with the ability to quickly understand unfamiliar systems and work effectively with incomplete information.

Strong Plus:

• Open-source contribution experience, particularly sustained involvement in an existing project.

• Experience working with AWS, at either application or platform level.

• Experience with distributed systems, storage, or protocol conformance.

Nice to Have:

• Deep AWS expertise.

• Experience with Infrastructure as Code, such as Terraform, CDK, or Pulumi.

• Experience with Kubernetes and microservices architecture.