Currently, prioritizr supports a variety of commerical and open source solvers. Although the open source solvers can solve medium sized problems relatively quickly (e.g., less than 50k planning units), commercial solvers are required for larger problems. Indeed, if using complex penalties or constraints (e.g., boundary penalties, or connectivity penalties), then they may only be able to solve relatively small problems within a short period of time (eg., 10k planning units or fewer). Despite the fact that the Gurobi and CPLEX solvers have state of the art performance, their costs may be prohibitive for small organizations (e.g., CPLEX is 465 NZD per month so 5580 NZD per year*, https://www.ibm.com/products/ilog-cplex-optimization-studio/pricing). As such, it may be worth adding support for other commerical solvers that -- while not being as fast as Gurobi and CPLEX -- may be faster than the open source solvers and have relatively cheap licensing costs.

Is this something people working in consultancies, non-governmental, or governmental organizations would be interested in? Since users affiliated with universities can use academic licenses for Gurobi and CPLEX, I don't think adding this functionality would benefit such users. For example, MOSEK (https://www.mosek.com/) is the cheapest commerical MILP solver that I could find and has a cost structure of paying 2250 USD (~3751 NZD) for the first year and 562.50 USD for subsequent years (~937.90 NZD) (https://www.mosek.com/sales/commercial-pricing/). If MOSEK had decent performance for solving conservation planning problems and prioritizr supported MOSEK as a solver, is MOSEK cheap enough that you would consider using it? Please understand that my goal here is to gauge interest and effectively prioritize development efforts. In other words, if no one's actually interested in this, then I can better spend developmental time on other stuff that would actually help users.

If you're a prioritizr user and working in a consultancy, non-governmental, or governmental organization - could you please let me know what you think? If you don't feel comfortable posting online, please feel free to contact me via email (my email address is in my GitHub user profile, https://github.com/jeffreyhanson).

• I can't see the USD prices for CPLEX - if anyone based in the US wants to tell me this I can add this in.