Bundler Reporting
bundle outdated is a naive report of what’s older than current (and what the current versions are).
next_rails ships with some additional tooling - bundler_report outdated will enhance the previous with release dates.
libyear for Python inspired libyear-bundler which will sum up the diff between the current version’s release date and the latest version’s release date, and tell you how many lib-years you are behind latest. It has a few runtime modes, but libyear-bundler --all does everything.