We spent the last article making the app fast. This one is about making sure it's still standing when someone tries to break it. That's the uncomfortable truth about security work: nobody notices it when it's done right, and everybody notices the one gap you missed.
This is part of the Full Stack SaaS Masterclass, a series that builds a multi-tenant SaaS end to end. Security is a mindset that touches auth, the database, the API layer, and the infrastructure around all of it, not a single article's worth of work. What follows is the checklist I actually run through before calling something production-ready, with the reasoning behind each item so you can decide what applies to your own app.
I'm resisting the urge to list forty things here. Most of the OWASP Top Ten is either handled by your framework already or irrelevant until you've earned the complexity that creates the risk. What follows is the subset that actually bites SaaS teams in practice.
Authentication and session handling
Get this wrong and nothing else matters. If someone can impersonate another user, your rate limiting and your input validation are decorating a house with an open front door.
