This is a tool that uses randomized testing to find under-invalidation bugs in web browsers. It's already found a lot of bugs in Chrome (1137427, 1166887, 1189755 [fixed], 1189762, 1190220 [fixed], 1219641, 1224721, and 1229681) and Firefox (1721719, 1724991, 1724982, linked to metabug 1724999). As of writing, sifting through bugs and preparing bug reports is the most time-intensive part of this process.
You can run the project in selenium. See the docs here Or with Mozilla's Fuzzing Framework, Grizzly. See the docs here
Licensed for use through the MIT License.