Show HN: A tool that alerts when 404s silently return 200)

Hey HN,

I recently ran into a scenario where a page that used to return a 404 suddenly started returning 200 — without warning. This led to the discovery of a forgotten admin endpoint being accidentally reactivated.

I wrote a short post about this issue and how it can surface subtle security or logic flaws.

Along the way, I built a small tool (ReconSnap) to help monitor this kind of thing — basically, it tracks web changes, auto-saves pages, and can react to specific conditions like status code flips, keyword appearance, or DOM mutations. It’s aimed mostly at security folks, OSINT researchers, and curious developers.

I realize this may seem like a bit of a promo, but I genuinely use it myself and figured it might be useful to others too. Feedback is welcome!

Here’s the post: https://medium.com/@heberjulio65/when-an-404-suddenly-turns-...