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How about a subscription service? Email me as soon as my installed gems are getting vulnerable.

Hah, well, okay, I didn't expect that page to read as too subtle.

It is a service! Visit https://appcanary.com for more deets.

Part of it might be the link to your site is only clearly marked "we have a service" after you open a Gemfile.lock.

Gemnasium.com offers this. (as does OP, see sibling comment)