yreclab is a locally hosted web version of the Yale Rotating Evolution Code (YREC), a fast, performant Henyey-style stellar evolution code with modern microphysics and additional prescriptions for rotation, angular momentum transport, and starspots. That means it runs locally in your own browser, with no data sent to external servers. All run information can be edited in-browser, and all namelists and output files can be downloaded at any point during execution.
In order to build YREC in this fashion, it has first been translated from FORTRAN77 to C with the utility f2c and subsequently compiled to WebAssembly with the emcc toolchain. There are slight differences from the traditionally Fortran-compiled version of YREC as the compiled version of YREC is not strictly F77-compliant; if any major discrepancies arise between the current version of YREC and the publicly available version of yreclab, please report them as an issue at the yreclab Github.
yreclab has the ability to pause and step through runs, as well as custom control through the web console. As a web laboratory, it can serve as a rapid prototyping tool for stellar evolution, a teaching tool for stellar physics, or to save runs which were done in the past.
If you make use of yreclab, please cite the main YREC public release paper (Pinsonneault et al. 2026) and the yreclab paper (Cao & Pinsonneault in prep).
yreclab was originally developed and maintained by Lyra Cao. Contributions and any suggestions for user content are welcome at the yreclab Github.