deal.II

deal.II
Initial release2000 (2000)
Stable release
9.7.0 / 22 July 2025 (2025-07-22)
Written inC++
Operating systemLinux, macOS, Microsoft Windows
TypeFinite element analysis
LicenseGNU Lesser General Public License 2.1 or later
Websitedealii.org
Repository

deal.II is a free, open-source library to solve partial differential equations using the finite element method.  The current release is version 9.7, released in July 2025. The founding authors of the project — Wolfgang Bangerth, Ralf Hartmann, and Guido Kanschat — won the 2007 J. H. Wilkinson Prize for Numerical Software for deal.II. The library's then-developers also won the 2025 SIAM/ACM Computational Science and Engineering Prize. Today, it is a worldwide project managed by around a dozen "Principal Developers"; over the years several hundred people have contributed substantial pieces of code or documentation to the project.