Language bindings
PROJ bindings are available for a number of different development platforms.
Excel
proj.xll: Excel add-in for PROJ map projections
Fortran
Fortran-Proj: Bindings for PROJ in Fortran (By João Macedo @likeno)
Go (Golang)
go-proj: Go bindings for PROJ.
Java
PROJ-JNI: Java Native Interface for PROJ
Julia
Proj.jl: Julia bindings and idiomatic wrapper for PROJ.
MySQL
fProj4: Bindings for PROJ in MySQL
Perl
Geo::LibProj::FFI: Foreign function interface for PROJ (version 6 and newer) in Perl
Python
pyproj: Python interface (wrapper for PROJ)
Ruby
proj4rb: Bindings for PROJ in ruby
Rust
proj: Rust bindings for the latest stable version of PROJ
TCL
proj4tcl: Bindings for PROJ in tcl (critcl source)
Visual Basic
PROJ VB Wrappers: By Eric G. Miller.