This page is for linking to available Fortran libraries and source code repositories. See Software repositories for collections of libraries and see Library distribution for methods for packaging and distributing Fortran libraries. Modern Fortran Libraries and Awesome Fortran are other lists of libraries.
Libraries linked here are classified as follows:
When available, the above tags should link to the license page for a particular library.
Fortran Standard Library - Utilities (containers, strings, files, OS/environment integration, unit testing & assertions, logging, …) Algorithms (searching and sorting, merging, …) Mathematics (linear algebra, sparse matrices, special functions, fast Fourier transform, random numbers, statistics, ordinary differential equations, numerical integration, optimization, …)(OS: MIT)
BeFoR64 - Base64 encoding/decoding library for FoRtran poor men, is a pure Fortran (KISS) library for base64 encoding/decoding for modern (2003+) Fortran projects. (OS: GPL)
coretran - easy-to-follow library to make Fortran easier in general with wrapped interfaces, sorting routines, kD-Trees, and other algorithms to handle scientific data and concepts.
erloff - make error-handling in Fortran a bit more flexible (OS: MIT)
fdict - native Fortran 90 dictionary with hash tables for retaining any data-type in a Python-like dictionary. (OS: MPL-2)
ferror - library to assist with error handling in Fortran projects.
ffhash generic and fast hash table similar to khash in C, by Jannis Teunissen.
FGSL - Fortran interface to the GNU Scientific Library. (OS: GPL)
FIAT - Fortran Implementation of Abstract Types
flib - standard library, function library, a tridiagonal matrix solver, and code for a doubly linked list, optimization, and interpolation. (OS: GPL-3.0 License)
flink - Flexible Fortran Modules and Subroutines for Scientific Computing. (OS: GPL-3.0 License)
Focal - modern Fortran module library which wraps calls to the OpenCL runtime API with a higher abstraction level appropriate to the Fortran language. (OS: MIT)
forpy - use Python in Fortran and vice versa. (OS:LGPL)
FortCUDA - Fortran interface to the CUDA GPU library. Contains a Python pre-processor to parse the CUDA C headers and creates ISO_C_BINDING interfaces for the method calls. Comes with a fairly complex example. (OS: GPL)
fortranlib - Collection of personal scientific routines in Fortran. (OS: BSD-2-Clause License)
Fortran-Library - Code for geometry transformations, nonlinear optimization, Fourier transforms, clustering, statistics, mathematics, linear algebra, strings, and chemistry. (OS: GPL-3.0 License)
fortran_notes - containers and advanced data structures, hash functions, and design patterns (OS: MIT)
Fortran Template Library (FTL) - generic containers, versatile algorithms, easy string manipulation, and more. (OS: GPL-3)
Fortran Template Library (FTL) - Object oriented implementation of generic containers similar to the C++ STL (Standard Template Library) in native Fortran 2003. (OS: LGPL-3)
fortran-utils - Various utilities for Fortran programs, including types, constants, sorting, saving/loading 2D arrays, meshes, cubic splines, saving/loading PPM images, Lapack interface, HDF5 interface, special functions, and optimization, by Ondrej Certik et al.
ForUtils - Fortran 2008 utility functions and reusable classes
FTObjectLibrary - provides a collection of reference counted Fortran 2003 classes to facilitate writing generic object oriented Fortran programs (OS: MIT)
fycollections - generic collection templates for Fortran
IMSL - most comprehensive mathematics and statistics library available. (C)
JAMS - collection of general Fortran modules offering miscellaneous functions in the categories Computational, Date and Time, Input / Output, Math / Numerics, Screening, Sensitivity Analysis and Optimising / Fitting, and Miscellaneous. Written by Matthias Cuntz, Juliane Mai and Stephan Thober. (OS: MIT)
jsonff - Fortran library for dealing with JSON data (OS: MIT)
json-fortran - Fortran 2003/2008 JSON API. (OS: BSD)
kdtree2 - kd-tree implementation in C++ (and Fortran) by Matthew B. Kennel
NAG - world’s largest collection of robust, documented, tested and maintained numerical algorithms for users of the Fortran programming language. (C)
NEC Numeric Library Collection - collection of mathematical libraries that powerfully supports the development of numerical simulation programs in a wide range of fields. The libraries are available on Vector Engine. (C)
NPY-for-Fortran allows the developer to save Fortran arrays in Numpy’s .npy format. (OS:MIT)
parff - (almost) functional style parser combinator library for Fortran (OS: MIT)
PENF - Fortran (standard 2003) module useful to achieve portable codes. The module makes available portable kind-parameters and some useful procedures to deal with them. (OS: GPL)
petaca - collection of modern Fortran modules that provide broadly useful capabilities – things that the author has found himself using repeatedly across many projects. A unifying feature of the modules is their object-oriented interfaces and implementation. (OS:MIT)
qContainers - container library for Fortran language. It enables to store any internal Fortran data type and any derived data type to the container. It implements containers for key/value pairs: tree table and hash table, and containers for objects: list and vector. (OS: BSD)
Processor - F95 compliant general purpose library version 1.8.6 with HTML documentation. Covers string/array manipulations, stacks, hashes, noise, interpolation, smoothing, physical constants, and dates. Includes wrapper modules for several OS/compiler combinations for specific system access functions.(OS: LGPL)
VectorClass Fortran 2003 dynamic memory array that functions similarly (but not identically) to the C++ Vector class, by Tyler Chang. (OS: MIT)
fortran_pcre - Fortran wrapper around the C PCRE regular expression library. (OS:MIT)
regex-fortran is a Fortran-based basic RegEx package
M_matchis a Fortran-based basic RegEx package
fortran-unix contains a RE interface
M_regex builds on the Wiki example to call Posix RE procedures
GTKcontains a RE interface
regexp provides a RE interface
iso_varying_string - implementation of the ISO standard for varying strings (OS: MIT)
M_strings - modules for processing strings. Routines for parsing, tokenizing, changing case, substituting new strings for substrings, locating strings with simple wildcard expressions, removing tabs and line terminators and other string manipulations are included. (OS)
strff - library of convenient string functions (OS: MIT)
fortran-regex is a full regex module implemented in modern Fortran, with no external dependencies. (OS: MIT)
afnl - Fortran 90 numerical library with modules for numerical types, constants, error handling, integration, optimization, linear algebra, sorting and search, special functions, statistics, polynomials, root-finding, Fourier transforms, and dates and times, by Alberto Ramos (OS: GPL-2.0 License)
ARPREC - C++/Fortran 90 library for arbitrary precision math. Includes a complete interactive high-precision arithmetic computing interpreter (“toolkit”) written in Fortran, that will integrate symbolic expressions etc. (OS: BSD)
datapac - Fortran 77 statistical library written by James Filliben (at NIST) (PD)
Emmix Fits a mixture model of multivariate normal or t-distributions to a user supplied data set via the EM algorithm. With gfortran, must be compiled with -std=legacy option.
faiNumber-Fortran - A fast, flexible, and secure numerical library for Fortran with fast number parsing as one of its features. (OS: MIT)
FMLIB - David M. Smith’s libraries for multiple precision computation. The package performs multiple-precision real, complex, and integer arithmetic, providing the intrinsic Fortran numerical functions, as well as many special functions. An existing Fortran program can be checked by converting it from double precision to FM arithmetic. (NC)
forSISL - Modern Fortran interfaces to the SINTEF Spline Library (SISL)
FURY - Fortran Units (environment) for Reliable phYsical math, by Stefano Zaghi
GMP Fortran library - Fortran binding for GNU Multiple Precision Arithmetic library.
HSL Mathematical Software Library - free for academic use.
lookup_table_fortran A module for linear lookup tables. Supports multiple columns and various ways to read values from the table.
MP - Fortran multiple-precision arithmetic package by Richard Brent.
MPFUN2020 - thread-safe arbitrary precision package by David H. Bailey
MPFUN90 (broken link) - a pure Fortran 90 library for arbitrary precision math. Includes a complete interactive high-precision arithmetic computing interpreter (“toolkit”) written in Fortran, that will integrate symbolic expressions etc. (OS: BSD)
Muesli - A free numerical and graphical Fortran 95 library written by Edouard Canot at Univ of Rennes (?)
National Wind Technology Center Subroutine Library - A library of general-use Fortran 2003 routines used in many NWTC computer-aided engineering tools (OS: GPL)
NumericalHUB - Set of modern Fortran numerical libraries covering: zeroes of Systems of Equations, Lagrange Interpolation, Finite Differences, Cauchy Problems, Boundary Value Problems, and Initial Boundary Value Problems, associated with book How to learn Applied Mathematics through modern FORTRAN
Numerical methods in Fortran - solving linear, nonlinear equations, integral, ordinary differential equations, … using numerical methods in Fortran, by Carlos Planelles Alemany
Numerical methods in Fortran - numerical analysis and statistics algorithms, by Murat Koptur.
Numerical Methods for Scientists and Engineers, code in Fortran 77 and C from book by H. M. Antia (OS: GPL-2.0 License)
Numerical Methods of Statistics, Fortran 95 code from book by John Monahan.
SLATEC - Common Mathematical Library: a comprehensive software library containing over 1400 general purpose mathematical and statistical routines written in Fortran 77. (PD)
SLATEC - Fortran 90 version by John Burkardt. (?)
SLICOT - The Control and Systems Library (GPL)
stspac, A Fortran 77 statistical library written by Charlie Reeves (at NIST) (PD)
physunits - Automated Computation and Consistency Checking of Physical Dimensions and Units in Scientific Programs, by Grant Petty
quaff - A library for making math with units a lot easier and more convenient (OS: MIT)
SciFortran - A library of fortran modules and routines for scientific calculations (in a way just like scipy for python). (OS: LGPL-3.0 License)
Simfit - package for simulation, statistical analysis, curve fitting and graph plotting, using models from a compiled library or from ASCII text files supplied by the user. Source code for over two hundred NAG library subroutines called by the Academic version of the Simfit package is available.
Tensor Toolbox for Modern Fortran (ttb)(OS: MIT License)
arpack-ng is a collection of Fortran77 subroutines designed to solve large scale eigenvalue problems.
BLAP95 (broken link) - a Fortran 95 interface to the Level 3 BLAS routines and key LAPACK computational and driver routines. (?)
DBCSR - Distributed Block Compressed Sparse Row matrix library (OS: GPL-2.0 License)
ELPA - Eigenvalue Solvers for Petaflop Applications (OS: LGPL-3.0)
LIBXSMM - library for specialized dense and sparse matrix operations as well as for deep learning primitives such as small convolutions.
linalg - linear algebra library that provides a user-friendly interface to several BLAS and LAPACK routines. (OS:GPL-3.0 License)
Fortran_Davidson - Modern Fortran implementation of the Davidson diagonalization algorithms. (OS:Apache-2.0 License)
fortran_lsp - Fortran routines from “Solving Least Squares Problems” by C. Lawson and R. Hanson, with improved interfaces.
JADAMILU - computes eigenvectors of large sparse symmetric matrices. Provided as a precompiled library
MUMPS - parallel sparse direct solver
NTPoly - massively parallel library for computing the functions of sparse matrices.(OS: MIT License)
qrupdate - library for fast updates of QR and Cholesky decompositions.
qr_mumps - package for the solution of sparse, linear systems on multicore computers
Sparskit - basic tool-kit for sparse matrix computations (Version 2)
UMFPACK Fortran interface - mUMFPACK module provides a Fortran-2003 implementation of the full UMFPACK interface closely corresponding to that defined in the UMFPACK User Guide.
Alan Miller’s Fortran Software for subset selection in regression, random number generation, logistic regression, linear least squares, and other topics.
apstat, a collection of subroutines (AS1 - AS319) published in the journal Applied Statistics 1968-1994. Most are Fortran. Personal favourites include AS319 and AS164. Many have been translated to Fortran 90 by John Burkardt and Alan Miller
BMSL mathematical and statistical libraries, geared toward environmental / hydrological applications, by Ben Renard.
Climate time series analysis by Manfred Mudelsee.
CONFINT - sample size calculation for confidence intervals
datapac, A Fortran 77 statistical library written by James Filliben (at NIST) (PD)
Fast Statistical Methods, by Rybicki and Press.
Fortran Programs for Global Optimization, etc programs for econometric analysis such as Non-linear Least Squares, Robust Regression, Robust Two-Stage Least Squares, Ordinal Canonical Correlation, Ordinal Principal Component Analysis, Hybridization of canonical correlation and principal component analysis, fitting origin-displaced logarithmic spiral to data, solving the nearest correlation matrix problem, completing the correlation matrix, construction of composite indices by linear aggregation, etc. some of which are based on global optimization.
MCMC f90 library - do Markov chain Monte Carlo simulation from a posterior distribution of unknown model parameters defined by a likelihood function and prior
MISCLIB, a library of statistical and support routines, written by Barry Brown (M.D.Anderson Cancer Institute) - open source
Modified Burg Algorithms in Multivariate Subset Autoregressive Modeling by A. Alexandre Trindade
MultiNest - Bayesian inference tool which calculates the evidence and explores the parameter space which may contain multiple posterior modes and pronounced (curving) degeneracies in moderately high dimensions, by Farhan Feroz and Mike Hobson
Multitaper Spectrum Estimation Library by Germán A. Prieto.
Multivariate Data Analysis Software in Fortran (and C) by Fionn Murtagh
Nonsmooth Clustering by Napsu Karmitsa. Also codes for regression and imputation
Oak Leaf - robust statistical estimates by Filip Hroch
ParaMonte - Plain Powerful Parallel Monte Carlo and MCMC Library for Python, MATLAB, Fortran, C++, C (OS: MIT License)
Random by Richard Brent. ranut is a uniform pseudo-random number generator which uses recurrences based on primitive trinomials, or in some cases trinomials which have large primitive factors (over the field GF(2)). rannw is a Fortran 77 pseudo-random number generator which uses a variant of Chris Wallace’s method to generate normally distributed (i.e. Gaussian) numbers.
RANDLIB - routines for nonuniform random number generation
SLICE, efficient N-Dimensional Monte Carlo inversion algorithm.
STATPACK - Fortran 95/2003 library for solving the most commonly occurring mathematical and statistical problems in the processing of (huge) climate model outputs and datasets, and more generally in data analysis
stspac, A Fortran 77 statistical library written by Charlie Reeves (at NIST) (PD)
SEQBIN - Bayesian/Frequentist Designs for Sequential/Group-Sequential Trials of a Single Binomial Parameter
STPLAN - performs power, sample size, and related calculations needed to plan frequentist studies
TIMSAC package for analysis, prediction and control of time series
Applied Statistics algorithm 298 Hybrid minimization routine using simulated annealing and a user-supplied local minimizer.
Applied Statistics algorithm 319 Variable metric unconstrained function minimization without derivatives.
cobyla.f90 Mike Powell’s routine for minimization of non-linear functions with smooth non-linear constraints, using local linear approximations to the constraints.
conmin.zip The classic CONMIN package for constrained minimization updated to Fortran 90.
CUTEst - Constrained and Unconstrained Testing Environment with safe threads for optimization software
DualSimplex Fortran 90 module for solving linear programs of the form max c^T x s.t. A x <= b where, c is a cost vector and A x <= b is a system of linear inequality constraints, by Tyler Chang.
FilterSD - Fortran 77 subroutines for solving nonlinear programming problems and linearly constrained problems in continuous optimization
GALAHAD is a library of modern Fortran modules for nonlinear optimization. (OS: lgpl-3.0)
libga - genetic algorithm optimisation library by Alberto Ramos
lm.zip Levenberg-Marquardt algorithm for non-linear least squares (unconstrained). This is a translation of the MINPACK routines, LMDER & LMDIF.
minim.f90 The Nelder-Mead simplex algorithm for unconstrained minimization. It does NOT require or use derivatives.
minuit - Fortran 77 library for function minimization and error Analysis by F. James (OS: GPL-2.0)
NLopt - NLopt is a free/open-source library for nonlinear optimization, providing a common interface for a number of different free optimization routines available online as well as original implementations of various other algorithms. By Steven G. Johnson (OS: GNU LGPL)
NonSmooth Optimization (NSO) Software by Napsu Karmitsa and coworkers
Optimization codes by Andrei Neculai THREECG: A simple three-term conjugate gradient algorithm which satisfies both the descent and the conjugacy conditions. DESCON: Conjugate Gradient Algorithm with guaranteed descent and conjugacy conditions for large-scale Unconstrained Optimization. ASCALCG: Accelerated Scaled Conjugate Gradient Algorithms for Unconstrained Optimization. AHYBRIDM: Accelerated Hybrid Conjugate Gradient Algorithm with Modified Secant Condition for Unconstrained Optimization. CONMIN: Shanno Conjugate Gradient with Beale restart memoryless variable metric algorithm for Unconstrained Optimization. ASA: Anticipative Scalar Approximation of Hessian for Unconstrained Optimization. RELAXED: Relaxed Gradient Descent Method with Backtracking for Unconstrained Optimization. UNO Fortran subroutines library for unconstrained optimization using searching methods.SPENBAR Sparse PENalty BARrier package for solving general nonlinear programming problems with equality and inequality constraints and simple bounds on variables. All the constrained are penalized. Minimization of the penalty function is given by TN package of S. Nash. FIBO Fibonacci method for function minimization. MAXFUN Powell direct search method for function maximization. ZERO Simple algorithms for computing zeros of a nonlinear function of a variable in a given interval.
PCx - interior-point predictor-corrector linear programming package
pikaia - Modern Fortran Edition of the Pikaia Genetic Algorithm by Jacob Williams
PowellOpt is a collection of derivative-free optimization algorithms by M.J.D. Powell.
qnstop suite of serial and parallel Fortran 95/2003 codes for deterministic global optimization and stochastic optimization by Layne Watson.
RALFit - non-linear least squares solver that is primarily developed by the Numerical Analysis group at STFC Rutherford Appleton Laboratory.
Roots of a real function in Fortran 90 by J-P Moreau
simulated-annealing - Simulated Annealing with Modern Fortran by Jacob Williams
tapenade - tool for automatic differentiation (forward/reverse) of Fortran and C programs
TENSOLVE contains both TOMS 739 (UNCMIN) for unconstrained minimization, and TOMS 768 (TENSOLVE) for the solution of sets of non-linear equations.
TOMS algorithm 778 solves bound-constrained optimization problems by using the compact formula of the limited memory BFGS updates.
TOMS algorithm 813 is for local minimization, with or without convex constraints. It requires the user to supply first derivatives. This version is in standard Fortran. It uses the so-called spectral projected gradient (SPG) method.
tn.zip Stephen Nash’s truncated-Newton code for the minimization of continuous functions. It can use differences instead of derivatives, and bounds may be imposed on the parameters.
tron.zip Newton’s method for large bound-constrained optimization problems by Chih-Jen Lin & Jorge More’, a MINPACK-2 project.
uobyqa.f90 Mike Powell’s package for unconstrained minimization when derivatives are not available.
VTDIRECT95: Fortran 95 implementation of D. R. Jones’ deterministic global optimization algorithm called DIRECT, which is widely used in many multidisciplinary design optimization problems
autofit is a Fortran code for fitting permutationally invariant polynomials (PIPs). (OS: Apache-2.0 License)
FortLearner - linear regression, logistic regression, stochastic gradient descent, decision trees, ensemble trees, boosting trees, and dimension reduction.
gpf - small Fortran library for Gaussian process regression. It currently implements value predictions with dense Gaussian processes, and projected-process approximate Gaussian processes. (OS: Apache-2.0 License)
neural-fortran is a parallel neural net microframework. (OS: MIT)
NN_MOD - Fortran 2008 Module/Class for training neural network regressors
accis - Fortran plotting and graphics library
cairo-fortran: Fortran bindings for libcairo. (GPL v3)
DISLIN - high-level scientific data plotting library. (NC)
EGGX/ProCALL - X11 graphics library for C and FORTRAN created to achieve extreme simplicity. Uses only (OS: GPL)
gtk-fortran - cross-platform library to build Graphical User Interfaces (GUI). It is a GTK / Fortran 2003 binding based on the ISO_C_BINDING module. (OS: GPL)
GNUFOR2 - Fortran 90 interface to Gnuplot which helps to plot graphs, surfaces, histograms and images. (?)
F03GL - Fortran 2003 bindings for OpenGL, GLU and GLUT (?)
F90GL - Fortran 90 bindings for OpenGL and the GL Utility Toolkit (GLUT) (PD)
g2 - easy to use, portable and powerful 2D graphics library. Currently supported devices: PostScript, X11, PNG and JPEG (using gd) and Win32 (xfig in development). g2 is written in C (ANSI) and has a Fortran interface. (OS: LGPL)
g95gl - alternate Fortran 95 (interop) bindings for OpenGL and the GL Utility Toolkit (GLUT)
giza - scientific plotting library for C/Fortran, meant as a replacement for pgplot, by Daniel Price
GrWin - Windows graphics library for FORTRAN and C.
libvogle - basic vector-based graphics library in C, but Fortran-callable
Lib_VTK_IO - pure Fortran library to write and read data conforming the VTK standard. This library is not a porting or a wrapper of the VTK code, but it is only an exporter/importer of VTK data format written in pure Fortran language (standard Fortran 2003). (OS: GPL)
MathGL - library for making high-quality scientific graphics under Linux and Windows via Qt, FLTK or OpenGL. (OS: GPL)
plotterf90 - graphics subroutine library producing Postscript written by Masao Kodama. (?)
pltFor - Fortran-Python interface library to plot figures directly in Fortran, by DamienMinenna
Pyplot-Fortran - simple module for generating plots from Fortran using Python’s matplotlib.pyplot.
text_viz - Text-mode 2D-Graphics for Fortran. (?)
Fortran and Matlab Codes for differential equations - from Ernst Hairer
FOODIE - Fortran Object-Oriented Differential-equations Integration Environment.
ODEPACK is a systematized collection of ODE solvers. (PD)
PETSc The Portable, Extensible Toolkit for Scientific Computation (PETSc, pronounced PET-see; the S is silent), is a suite of data structures and routines developed by Argonne National Laboratory for the scalable (parallel) solution of scientific applications modeled by partial differential equations.
PoisFFT - Free parallel fast Poisson solver.
numerical-anal boundary value problems and heat transfer.
Differential equations in Fortran by J-P Moreau
dop853 - Modern Fortran Edition of Hairer’s DOP853 ODE Solver, by Jacob Williams
ddeabm - Modern Fortran implementation of the DDEABM Adams-Bashforth algorithm, by Jacob Williams
INTEGRAL - routines for the integration of functions of various types and for integration of systems of ordinary differential equations (ODEs)
Quadrule - sets up a variety of quadrature rules, used to approximate the integral of a function over various domains in 1D, by John Burkardt. He has many other quadrature codes linked there
quadrature-fortran - Adaptive Gaussian Quadrature with Modern Fortran, by Jacob Williams
stroud - routines from the book Gaussian quadrature formulas by Stroud & Secrest (1966), translated to modern Fortran by Ivan Pribec
Fortran-parallel-sort Fortran library to perform parallel sorts using OpenMP, by Corentin Cadiou (OS: CC0-1.0 License)
hs-sort sorting routines in Fortran 77 by Houlsby & Sloan, with a modern Fortran wrappers by Ivan Pribec
ORDERPACK - library with routines for unconditional, unique, and partial ranking, sorting, and permutation. (?)
DelaunaySparse serial and parallel codes, written in FORTRAN 2003 with OpenMP 4.5, for performing interpolation in medium to high dimensions via a sparse subset of the Delaunay triangulation.
bspline-fortran - multidimensional B-spline interpolation of data on a regular grid, by Jacob Williams.
finterp - multidimensional linear interpolation with modern Fortran, by Jacob Williams.
WenOOF - WENO interpolation Object Oriented Fortran library
NIST Digital Library of Mathematical Functions has a software index for special functions
Special_Functions translated code from book “Computation of Special Functions” by Shanjie Zhang and Jian-Ming Jin to Fortran 90 by John Burkardt. Links to other codes for special functions are provided.
FFTPack provide an easily usable package of functions using FFTPack library (Fortran 77).
fftpack51 computes the Fast Fourier Transform, using double precision arithmetic, translated to Fortran 90 by John Burkardt
fortran-csv-module - read and write CSV Files using Modern Fortran.
csvio-f90, the CSVIO F90 module, is a Fortran 90 module for easily reading and writing CSV files. (OS: BSD)
xml-fortran (OS: BSD)
fortranposix - An implementation of some POSIX functions in Fortran 90/95. (OS: LGPL)
fortyxima/filesys - Modern Fortran wrappers around the file system interface of libc as part of the Fortyxima library: rename and remove files, recursively create and remove directories, obtain filenames in a directory, check whether a given file exists and if a directory or a symbolic link, obtain the current working directory and change to a directory, create hard links and symbolic links, resolve the target of symbolic links, canonize path names. Fortyxima/filesys replaces the old modfilesys library. (OS: BSD)
Posix90 - The Fortran 90 Posix interface project. (OS: GPLv2+)