Aaron Costley
Software Development Manager at Amazon
Chiyoda, Japan
Summary
🤩
Rockstar🎓
Top SchoolAaron Costley is a software development manager with 12+ years of experience who currently leads a 36-engineer, multinational team at Amazon, delivering scalable automation and business-process solutions for Operations across Japan, China, and India. He combines hands-on systems and API design expertise with people leadership—coaching underperformers, running regular career development, and growing his team from 3 to 36 while maintaining remote-first operations. Technically grounded in .NET, Java, and cloud SDKs, he has driven performance and security improvements in high-profile open-source projects such as the AWS SDK for .NET and the jsii runtime used by the AWS CDK. Aaron is pragmatic about engineering trade-offs, pioneers internal AI tooling to accelerate rearchitecture and BRD generation, and balances project delivery with non-saving initiatives like SOX compliance and vaccine inventory management. Skilled at cross-region stakeholder alignment, he thrives in ambiguous environments where technical rigor and operational discipline must meet diverse cultural contexts.
12 years of coding experience
12 years of employment as a software developer
Bachelor of Science (BS), Computer Science, 3.04, Bachelor of Science (BS), Computer Science, 3.04 at Tarleton State University
English, Japanese
Github Skills (17)
net10
dotnet10
cross-language10
security10
aws-sdk10
netframework10
asp-net10
cryptography10
dotnet-core10
csharp10
testing9
nodejs7
typescript7
typescript-types7
typescripts7
Programming languages (9)
Github contributions (5)
aws/aws-sdk-net
Mar 2018 - Aug 2020
The official AWS SDK for .NET. For more information on the AWS SDK for .NET, see our web site:
Role in this project:
Back-end Developer & Security Engineer
Back-end Developer & Security EngineerContributions:65 commits, 8 PRs, 12 pushes in 2 years 6 months
Contributions summary:Aaron made several contributions focused on enhancing the security and reliability of the AWS SDK for .NET. These changes include migrating from `System.Random` to `System.Cryptography.RandomNumberGenerator` for generating random numbers, fixing a security crypto bug, and increasing the ephemeral key length to 1024 bits. The user also implemented security compliance tests for CognitoAuthentication extension library, ensuring modulus and ephemeral key lengths adhere to SRP guidelines. Furthermore, the user addressed a security concern by explicitly enabling TLS 1.1/1.2 when the SecurityProtocol is not set to SystemDefault.
dotnetweb-sitesdkaws-sdkcsharp
aws/jsii
Aug 2018 - Jan 2019
jsii allows code in any language to naturally interact with JavaScript classes. It is the technology that enables the AWS Cloud Development Kit to deliver polyglot libraries from a single codebase!
Role in this project:Back-end Developer
Back-end DeveloperContributions:20 commits, 13 PRs, 4 pushes in 5 months
Contributions summary:Aaron primarily contributed to the .NET code generation and runtime components of the `jsii` project. Their work included adding features for .NET reference documentation generation, enhancing performance with assembly load caching, and fixing issues related to proxy implementations for abstract classes. They also addressed runtime issues, such as EPIPE errors, and improved error handling and debugging capabilities related to the node process. Additionally, the user made updates to the compliance tests for .NET.
aws-cloudany-languagedeliverawscodebase
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