Pythagorean Triples in JAVA
- A JavaScript applet which reads a and gives integer solutions of a^2+b^2 = c^2.
- http://www.hbnweb.de/pythagoras/pythagoras.html

Developing A General 2nd Degree Diophantine Equation x^2 + p = 2^n
- Methods to solve these equations.
- http://oas.ucok.edu/OJAS/98/T98/THIENDO.HTM

Linear Diophantine Equations
- A web tool for solving Diophantine equations of the form ax + by = c.
- http://www.thoralf.uwaterloo.ca/htdocs/linear.html

Diagonal Quartic Surfaces
- Articles, computations and software in Magma and GP by Martin Bright.
- http://www.boojum.org.uk/maths/quartic-surfaces/

Rational and Integral Points on Higher-dimensional Varieties
- Some of conjectures and open problems, compiled at AIM.
- http://aimath.org/WWN/qptsurface2/

Diophantus Quadraticus
- On-line Pell Equation solver by Michael Zuker.
- http://www.bioinfo.rpi.edu/~zukerm/cgi-bin/dq.html

Pell's Equation
- Record solutions.
- http://www.ieeta.pt/~tos/pell.html

Solving General Pell Equations
- John Robertson's treatise on how to solve Diophantine equations of the form x^2 - dy^2 = N.
- http://hometown.aol.com/jpr2718/pelleqns.html

Rational Triangles
- Triangles in the Euclidean plane such that all three sides are rational. With tables of Heronian and Pythagorean triples.
- http://grail.cba.csuohio.edu/~somos/rattri.html

Diophantine m-tuples
- Sets with the property that the product of any two distinct elements is one less than a square. Notes and bibliography by Andrej Dujella.
- http://www.math.hr/~duje/dtuples.html

Quadratic Diophantine Equation Solver
- Dario Alpern's Java/JavaScript code that solves Diophantine equations of the form Ax^2 + Bxy + Cy^2 + Dx + Ey + F = 0 in two selectable modes: "solution only" and "step by step" (or "teach") mode. There is also a link to his
- http://www.alpertron.com.ar/QUAD.HTM

Hilbert's Tenth Problem
- Given a Diophantine equation with any number of unknowns and with rational integer coefficients: devise a process, which could determine by a finite number of operations whether the equation is solvable in rational integers.
- http://www.ltn.lv/~podnieks/gt4.html

Pythagorean Triplets
- A Javascript calculator for pythagorean triplets.
- http://www.faust.fr.bw.schule.de/mhb/pythagen.htm

Diophantine Geometry in Characteristic p
- A survey by José Felipe Voloch.
- http://www.ma.utexas.edu/users/voloch/surveylatex/surveylatex.html

Thue Equations
- Definition of the problem and a list of special cases that have been solved, by Clemens Heuberger.
- http://finanz.math.tu-graz.ac.at/~cheub/thue.html

The Erdos-Strauss Conjecture
- The conjecture states that for any integer n > 1 there are integers a, b, and c with 4/n = 1/a + 1/b + 1/c, a > 0, b > 0, c > 0. The page establishes that the conjecture is true for all integers n, 1 < n <= 10^14. Tables and software by
- http://math.uindy.edu/swett/esc.htm

Egyptian Fractions
- Lots of information about Egyptian fractions collected by David Eppstein.
- http://www.ics.uci.edu/~eppstein/numth/egypt/

Bibliography on Hilbert's Tenth Problem
- Searchable, ~400 items.
- http://liinwww.ira.uka.de/bibliography/Math/Hilbert10.html