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PSF Developers in Residence

The Python Software Foundation’s Developer in Residence Program supports full-time developers who are focused on improving the Python programming language and its ecosystem. These developers play a crucial role in advancing Python’s core development, maintaining critical infrastructure, and supporting the broader community through mentorship, documentation, and tooling. Their work also addresses essential areas such as packaging, supply chain security, and the continued development and maintenance of PyPI, ensuring Python remains reliable and accessible for users and contributors worldwide.

Our Developers in Residence (DiR) and their work are often funded directly by sponsors. If your organization sees a gap in the Python ecosystem they want to fill with a focused DiR, we are open to additional support for the program. We welcome you to reach out to the [email protected] with inquiries or questions.

Łukasz Langa

Over the years as the PSF's CPython Developer in Residence, Łukasz Langa has played a key role in shaping the future of Python. He’s worked on everything from improving the user experience—like helping introduce a more modern, user-friendly Python shell—to keeping releases on track and stable. As a longtime release manager and core developer, he’s been involved in many versions of Python, making sure things run smoothly behind the scenes. Łukasz also spends time mentoring others and supporting big-picture changes that help Python grow and evolve for the long term.

Łukasz's role is generously sponsored by Meta.

Find Łukasz on all the platforms via his website.

Mike Fiedler

As PyPI’s sole Safety & Security Engineer, Mike focuses on ensuring that all users of PyPI - directly and indirectly - can rest easier knowing that the projects they rely on remain secure. He spends most of his time with the warehouse codebase, the underlying open source project that makes up PyPI.org and serves millions of requests a day. Mike works with communities of security researchers, developing methods to enable rapid response, and increases overall safety of the platform for everyone.

As of 2025, Mike’s role is now sponsored by Alpha-Omega. Mike is likely the person responding to your malicious project reports, say hi sometime!

Find Mike on all the platforms via his lnk.bio.

Petr Viktorin

As Deputy Developer in Residence for the PSF, Petr Viktorin focuses on the unglamorous but important work that keeps CPython running smoothly. He’s spent much of his time triaging Buildbot failures, reviewing PRs, and discussing issues—leaving room for volunteers to step in, but digging in himself when needed. He’s reviewed 100+ PRs, commented on hundreds of issues, and authored 56 PRs, often in less-loved parts of the codebase, like ctypes. He’s active in the C API working group, helped with community efforts like PyPI name retention, and speaks at events like PyCon and EuroPython.

Petr's role is generously sponsored by Bloomberg.

Find Petr on his Mastodon account.

Serhiy Storchaka

As the PSF's Supporting Developer in Residence, there is no single area of interest for Serhiy. He's active in so many parts of the interpreter and standard library that we're suspicious if he's really a single person. Serhiy is often the fastest responder on new issues and a champion of resolving and closing old ones. His quick reactions and consistent output make Serhiy invaluable for fixing crashes, release blockers, and other obscure issues that puzzle the average core developer.

Serhiy's role is generously sponsored by an anonymous donor.

Seth Larson

As Security Developer-in-Residence Seth focuses on the security posture of the CPython language runtime, Python packaging tools, and the broader Python package ecosystem interactions with vulnerability infrastructure, security standards, and public policy such as the Secure Software Development Framework and EU Cyber Resilience Act. Seth’s work primarily involves the authoring, reviewing, and implementation of standards such as Python Enhancement Proposals (PEPs) and guides on security practices for open source projects. Seth also functions as a coordinator for security incidents affecting many projects in the Python ecosystem, such as handling the follow-up from the backdoor of xz-utils.

Seth’s role has been sponsored by Alpha Omega since May 2023.

Find Seth online:

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