There is a wide range of freely-available software for simulating and modeling microlensing events. Click a package name to see more details.

Event modeling and simulation

pyLIMA
Lead developer
Etienne Bachelet, Las Cumbres Observatory
Collaborators
Valerio Bozza, University of Salerno, Rachel Street, Martin Norbury, Las Cumbres Observatory
Download
pyLIMA Github Repo
Documentation
pyLIMA documentation
Publications
Bachelet, E. et al. (2017) AJ, 154, 203
VBMicrolensing
Lead developer
Valerio Bozza, Università Degli Studi Di Salerno
Download
VBBinaryLensing Github repo
Publications
Bozza, V. (2010) MNRAS, 408, 2188
Bozza, V. et al. (2018), MNRAS, 479, 5157
Bozza, V. et al. (2021) MNRAS, 505, 126
Bozza, V. et al. (2025), A&A, 694, 219
RTModel
Lead developer
Valerio Bozza, Università Degli Studi Di Salerno
Download
RTModel Github repo
Website
Real time modeling results
Publications
V.Bozza, (2024), A&A, 688, 83,
Documentation
RTModel documentation
MuLAN
Lead developer
Clement Ranc, NASA Goddard Space Flight Center
Collaborators
Arnaud Cassan, Institut d'Astrophysique de Paris
Download
muLAn Github Repo
Documentation
muLAn documentation
MuLensModel
Lead developer
Radek Poleski, Ohio State University
Collaborators
Jennifer Yee, CfA Harvard
Download
MuLensModel Github Repo
Documentation
MuLensModel documentation
Publications
Poleski and Yee et al. (2018)
BAGLE
Lead developer
Jessica Lu, UC Berkeley
Collaborators
Casey Lam (Carnegie Observatories), Michael Medford, Natasha Abrams (UC Berkeley), Sean Terry (University of Maryland and NASA Goddard Space Flight Center), Jeff Chen (UC Berkeley), and Niranjan Bhatia (UC Berkeley)
Download
BAGEL Github Repo
Documentation
BAGEL documentation
eesunhong
Lead developer
David Bennett, NASA Goddard
Collaborators
Sun Hong Rhie, Greg Olmschenk
Download
eesunhong Github Repo
Publications
Several, see in particular:
Bennett and Rhie (1996)
Bennett (2010)
nbi — Neural Bayesian Inference for microlensing
Lead developer
Keming Zhang, UC San Diego
Download
nbi Github Repo
Publications
Zhang et al. (2023)
MAGIC microlensing
Lead developer
Haimeng Zhao and Wei Zhu, Tsinghua University
Download
Github Repo
Publications
Zhao & Zhu et al. (2022) AJ, 164, 192
MicroJax
Lead developer
Shota Miyazaki and Hajime Kawahara
Download
Github Repo
Publications
Miyazaki, S., & Kawahara, H. 2025, ApJ, 994, 144
MicroLux
Lead developer
Haibin Ren
Download
Github Repo
Publications
Haibin, R. & Zhu, W. (2025), AJ, 169, 3
Twinkle
Lead developer
Suwei Wang
Download
Github Repo
Publications
Wang et al, (2025), ApJS, 276, 40

Galactic models and population synthesis

PopSyCLE
Lead developer
Casey Lam, Carnegie Observatories
Collaborators
Jessica Lu (UC Berkeley), Michael Medford, Natasha Abrams (UC Berkeley), Sam Rose (Caltech)
Download
PopSyCLE Github Repo
Publications
Lam et al. (2020)
Rose et al. (2022)
genulens
Lead developer
Naoki Koshimoto, Nunota Kansuke
Download
Github Repo
Publications
Koshimoto, Baba & Bennett (2021), ApJ, 917, 78
SynthPop
Lead developer
Macy Hudson et al.
Download
Github Repo
Publications
Hudson, M. et al. (2026), arXiv: 2603.12219v2

Parameter Inference

Once a microlensing event has been modeled it is possible to combine all information on the system to infer the properties of the lensing system. The following packages exist for this purpose.

PyLIMASS
Lead developer
Etienne Bachelet
Download
Part of PyLIMA's Github Repo
Publications
E. Bachelet et al. (2024), AJ, 169, 24
PopClass
Lead developer
Peter McGill
Download
Github Repo
Publications
G. Sallaberry, et al. (2025), Journal of Open Source Software, vol. 10, id. 7769