AWS Open Source Blog
We’re excited to share that the Swift AWS Lambda Runtime project has officially moved to the AWS Labs organization. You can now find it here: 👉 https://github.com/awslabs/swift-aws-lambda-runtime
This move marks a new chapter for the project, while maintaining full continuity with its roots.
A thank you to the Swift community
The Swift AWS Lambda Runtime was originally created seven years ago by the Swift community (the initial commit was made the 1st of November 2018), as part of a broader effort to make Swift a powerful choice for server-side development. Since then, the project has been an incubating project as part as the …
AWS Open Source Blog
We’re excited to share that the Swift AWS Lambda Runtime project has officially moved to the AWS Labs organization. You can now find it here: 👉 https://github.com/awslabs/swift-aws-lambda-runtime
This move marks a new chapter for the project, while maintaining full continuity with its roots.
A thank you to the Swift community
The Swift AWS Lambda Runtime was originally created seven years ago by the Swift community (the initial commit was made the 1st of November 2018), as part of a broader effort to make Swift a powerful choice for server-side development. Since then, the project has been an incubating project as part as the Swift Server Workgroup (SSWG).
We want to thank the 58 contributors who have helped shape this project through their code, feedback, and support. Their collective work established a solid foundation that has allowed Swift developers to confidently run their code on AWS Lambda.
Why choose Swift for your server-side workload
Swift has evolved far beyond its origins as a language for Apple platforms — it’s now a robust, high-performance choice for building modern server-side systems. Swift’s combination of type safety, predictable performance, and developer-friendly syntax makes it an appealing option for backend services where reliability, maintainability, and scalability matter most.
Over the past few years, several organizations have successfully deployed Swift in production on the server. According to the Swift.org ecosystem overview, companies migrating from other languages have achieved impressive results: one reported a 4× performance increase after switching to Swift, while another saw 40 % more throughput, 50 % less hardware usage, and 90 % lower memory consumption compared to their Java-based implementation. Web frameworks such as Vapor and Hummingbird have made Swift a first-class option for developing REST APIs, microservices, and event-driven systems.
Whether you’re building a traditional web service, a distributed system, or serverless functions, Swift provides the safety and speed developers expect — without compromising on readability or productivity.
Why choose Swift for your Lambda functions
The Swift AWS Lambda Runtime allows you to write Lambda functions using the Swift programming language, bringing the language’s safety, performance, and expressiveness to the world of serverless computing.
In an event-driven architecture like AWS Lambda — where functions start and stop on demand and billing is measured in milliseconds — every millisecond and megabyte matters. Swift’s design makes it especially well-suited for this environment: it’s fast to start, efficient in memory use, and helps developers produce safe, predictable code that performs consistently under varying loads.
Here are a few of the advantages that make Swift a great fit for Lambda workloads:
- Performance – Swift is fast, leveraging LLVM optimizations and native execution on Amazon Linux environments.
- Memory efficiency – Swift’s small memory footprint and automatic memory management are crucial in Lambda’s constrained runtime environment, directly impacting both performance and cost.
- Type safety – Swift’s strong typing and compiler checks help catch errors at build time, reducing runtime issues.
- Concurrency safety – Swift’s strict concurrency checking at compile time helps prevent data races and concurrency bugs before deployment.
- Modern developer experience – Swift’s concise syntax, rich type system, and expressive APIs make it easy to write, test, and maintain Lambda functions efficiently.
Whether you’re building APIs, event-driven microservices, or data processing functions, Swift offers a powerful, modern option for your serverless workloads.
What changes — and what stays the same
Going forward, governance of the project will transition to AWS, under the AWS Labs GitHub organization. There will be no major changes in how the project works today. The same codebase, APIs, and open source spirit remain intact. The project remains an incubation project as part of the Swift Server Workgroup.
Our goal with this move is to increase visibility for the runtime and make it easier for Swift developers — and the broader serverless community — to discover, use, and contribute to it. By hosting it under AWS Labs, we hope to strengthen the collaboration between the Swift open source communities and AWS teams, and to encourage more experimentation and innovation in this space.
Open source Lambda runtimes
Swift joins a growing family of open source Lambda runtimes maintained by the community and AWS. If you’re working with other languages, you might be interested in exploring all the open source Lambda runtimes in the official documentation.
Get involved
The Swift AWS Lambda Runtime remains an open source project, and community contributions are at its heart. We warmly welcome issues and pull requests from developers who want to help improve the runtime or extend its capabilities.
Visit the repository, explore the documentation, and join us in building the next generation of Swift serverless applications:
👉 https://github.com/awslabs/swift-aws-lambda-runtime