UEML is supported by a set of prototype tools used to maintain and evolve the web of languages. There are currently four tools in the set: * The UEMLBase is a Protege-OWL repository that implements the representation meta-meta model described earlier. * The UEMLBase Manager is a Java-plugin for Protege-OWL that adds merging, reporting and other housekeeping functions to the repository. * The UEMLBase Verifier is a set of Prolog rules and a Prolog rule checker, which together provide formal verification of the UEMLBase repository. * The UEMLBase Analyser uses the repository to compute similarity measures between UEMLBase constructs, paving the way for consistency checking, automatic update reflection, model-to-model translation across languages, as well as other integrated model uses.