RELVIEW, developed in Kiel (formerly in Munich)
RELVIEW is an interactive tool for computer-supported manipulation of relations represented as Boolean matrices or directed graphs, especially for prototyping relational specifications and programs.

CrocoPat, developed in Lausanne, Berkeley, and Cottbus
CrocoPat is a tool for simple and efficient relational computation, manipulating relations of any arity.

PCP - Point and Click Proofs, developed in Orange, California
The interactive "Point and Click Proof" (PCP) environment allows the investigation of algebraic theories, such as groups, rings, lattices, and others, including relation algebras.

RATH, developed in Munich
RATH is a collection of Haskell modules that allow exploration of (finite) relation algebras and several weaker structures such as categories, allegories, and Dedekind categories.

RelAPS, developed in St. Catherines, Ontario
RelAPS is an interactive system assisting in proving relation-algebraic theorems.

Libra, developed in Adelaide
Libra is a relational programming language that explores the different values yielded by relations by back-tracking rather than parallel execution.

RALF, developed in Munich, currently not maintained
RALF is a relation-algebraic formula manipulation system and interactive proof checker. Its meta language is first-order predicate logic in calculational style. Proofs are manipulated via a graphical user interface: theorems are represented as trees and the subexpression to be transformed can be selected by mouse click.

RALL, developed in Munich, currently not maintained
RALL embeds the theory of abstract relation algebras in Isabelle.