The C API Summit aims to bring together various stakeholders of Python’s C API to discuss its current state, address challenges, and align on ongoing work.

Anyone with a valid in-person EuroPython 2025 ticket can join (Tutorials, Conference-only, or combined).
We are particularly looking for contributors and maintainers of:

• Python implementations with a C API (e.g., CPython, PyPy, GraalPy, MicroPython)
• Binding generators and alternative APIs (e.g., HPy, Cython, pybind11, PyO3, SWIG)
• Libraries that use the C API heavily or in innovative ways
• Applications that embed Python
• Similar projects working in this area

Presentations

If there is a topic you would like to present, please indicate it in the registration form and fill it in early.

Summit presentations are brief, intended to get everyone on the same page and start a discussion. Time slots are of 30min at most: maximum of 10 min of presentation, followed 20+ minutes for discussion.

We are looking to discuss advanced topics.

Tentative Agenda (subject to change)

• 9:00: Meet and greet – unconference-style post-it board organization
• 9:30: Presentations
• 9:30 Victor Stinner -- Deprecate the private API and add public functions to replace them
• 10:00 Petr Viktorin -- Are we ready for the revolution?
• 10:30 (TBD -- submissions still open)
• 11:00: Coffee break
• 11:15 Presentations
• 10:30 Stepan Sindelar
• 11:15 Mark Shannon -- What CPython needs from a new C API
• 11:35 Antonio Cuni -- The HPy Dilemma
• 12:15 (TBD -- submissions still open)
• 12:45: Lunch
• 13:45: Unconference-style activities (discussions, hacks, ad hoc tutorials, etc.)
• 15:30: Round-up/plenary session for feedback and planning next steps
• 17:00: Conference room closes
• 18:30: Dinner (in the city)

Registration

To be part of the C API summit, register your interest now! 👈

Please register early. If you are not yet sure if you can come, note it on your registration. You can change your answer later.

If you need help getting a ticket for EuroPython, say so on the form and we'll try to figure something out.

If you can, plan to stay for the whole conference, to have plenty of time to follow up on discussions and new friendships.

We will contact you with confirmations and more details closer to the event.