Aliquot A DOS tool to compute aliquot chains with small starting numbers, by Ivo Düntsch.
apfloat High-performance arbitrary precision arithmetic package for C++ and Java.
ARIBAS An interactive interpreter for big integer and multi-precision floating point arithmetic with a Pascal/Modula like syntax. It has several builtin functions for algorithmic number theory.
BIG_INT A library of functions to handle arbitrary length integers, written on ANSI C99.
CALC A calculator program for doing arbitrary precision integer arithmetic, written in ANSI C and Yacc, with a number of built-in functions for number theory, by Keith Matthews.
ECMNET Project to factor numbers using the elliptic curve method. Client and server software.
Encyclopedia of Integer Sequences Seeker EIS-Seeker is a libguile-based scheme interpreter devoted to the study of the Encyclopedia of Integer Sequences database. It is intended to help find new relations between sequences. C/Scheme, Posix.
Factorizer A Windows program to find all factors of any positive integer less than 2^31 - 1; decompose numbers into their prime constituents; find prime numbersand pairs of primes; and to plot Erdos-Kac and Palmen Color histograms. Down load free demo, order full version online.
GNU MP Home Page Free library for arbitrary precision arithmetic.
GNUBC Supports arbitrary precision integer arithmetic calculations with interactive execution: it is a superior version of the basic bc program which comes with the UNIX operating system. Keith Matthews has written several number-theoretic programs.
HiPiLib - High Performance Libraries Home of PIOLOGIE, a library for arbitrary precision arithmetic, operating on natural, integer and rational numbers.
HiPiLib - High Performance Libraries Home of PIOLOGIE, a library for arbitrary precision arithmetic, operating on natural, integer and rational numbers. Also used for calculating pi.
KANT / KASH KANT is a software package for sophisticated computations in number fields and in global function fields. With KASH you are able to use the powerful KANT V4 functions within a shell.
Kaprekar Series Generator A java application for determining the Kaprekar Constants and Series for numbers in various radixes.
L A C++ class library, datasets and command line program for computing zeros and values of L-functions, by Michael Rubinstein.
LiDIA C++ Library For Computational Number Theory.
LiDIA Group Based at the Darmstadt University of Technology, Germany. LiDIA is a C++ library for computational number theory which provides a collection of highly optimized implementations of various multiprecision data types and time-intensive algorithms.
NTL: A Library for doing Number Theory A high-performance, portable C++ library providing data structures and algorithms for manipulating signed, arbitrary length integers, and for vectors, matrices, and polynomials over the integers and over finite fields.
SAGE System for Arithmetic Geometry Experimentation: a framework for number theory, algebra, and geometry, initially designed for computing with elliptic curves and modular forms, by William Stein. Open source under GPL.