In the UK, we store a lot of data about our health; the NHS has its own databases, and other medical professionals, such as GPs, store their own too. Naturally, we want to use this data to draw conclusions about public health, and make informed decisions about policy and treatment. Unfortunately, it's not as simple as downloading a CSV or arrow file onto your laptop and running some code: we need to care about privacy (obviously) and reproducibility (this is science, after all!).

Existing approaches, such as Trusted Research Environments, address these concerns _to an extent_. But they still require researchers to abide by an honour system when it comes to privacy, and the precise research methodologies and code used for a particular study aren't captured and made public. Enter OpenSAFELY.

Born during early COVID, OpenSAFELY is both a sensitive data research philosophy, and the set of tools built to enable researchers to act upon that philosophy. At the Bennett Institute in Oxford, we've been building the next generation of healthcare data research software, which allows open, reproducible and secure usage of data provided by GPs in the UK.

We've got our own domain-specific query language, our own output checking and file release system, and our own network of researchers and healthcare professionals who are helping us build the right tools for the job. We've also got a lot of problems to solve. Come along to this talk to learn about them, our story, and where we hope to go next.