RDKit User Group Meeting

15th RDKit User Group Meeting 2026

RDKit is an important open-source cheminformatics and machine learning tool that has more than 100,000 users worldwide. This year's RDKit User Group Meeting took place from 16-18 September at Merck's facility in Darmstadt, Germany, and also celebrated their 20th birthday. Elixir Software were once again proud sponsors of the RDKit UGM, and our Senior Back-End Developer, Dr Huw Jones attended last month's event. Here, he shares his insights into the meeting and some of the latest developments.

"Last month I attended my third RDKit User Group Meeting, the fifteenth overall, hosted this year by Merck in Darmstadt. It is an unusual conference; Greg Landrum, who started the toolkit and still leads it, opened by pointing out that the meeting is organised entirely by volunteers and asking people not to expect a professional one, which is both true and rather the point.

The room held academics, people from large pharma, software vendors, and a good number of developers who simply maintain something that depends on RDKit, and valuable conversation moves between those groups without much ceremony.

This year also marked twenty years since the first RDKit release in 2006.

Upcoming Releases

The programme covered a number of changes arriving over the next couple of releases. The Python bindings are being rebuilt on nanobind, a change that should bring better introspection and richer type information to the Python API. That is potentially a significant improvement for anyone building on RDKit in Python, ourselves included. The ring perception code has had bugs corrected that could affect aromaticity perception on complex ring systems. And ChemDraw's own CDX and CDXML parsers, open sourced by Revvity, have now been wrapped for RDKit.

Event Highlights

The real value, though, was being able to put questions directly to the people who maintain the code. We had several things that had been sitting in our notes for months. The answers took minutes rather than the weeks of inference they would otherwise have cost, and in one case confirmed that the approach we had already settled on was the right one. In Greg's case, admittedly, that meant getting up at five in the morning and being able to keep up with him on a run!"

Summary

This year's RDKit UGM proved to be another successful meeting, bringing together over 300 chemists, data scientists and developers in Darmstadt to celebrate 20 years of the open‑source toolkit. It showcased how RDKit has grown from small‑molecule cheminformatics into a foundation for AI‑driven research across modalities like oligonucleotides, peptides and quantum chemistry.