The SaaS Security Checklist Every Solo Founder Needs

Shipping fast is the default mode for solo founders, but speed creates blind spots. Most SaaS apps built with AI-assisted coding tools share a common set of security gaps: unauthenticated API routes, missing rate limiting, overly permissive database rules, and secrets baked into client-side bundles. The good news is that these issues are predictable, which means you can check for them systematically before they become incidents. This checklist distills the 12 highest-impact items we see across hundreds of scanned apps into a single pass you can run before any launch.

Start with authentication and authorization. Verify that every API route checks for a valid session token, not just the pages that render user data. A surprising number of apps protect the frontend with login gates but leave the underlying API endpoints wide open. Next, confirm that your database enforces access control at the data layer. If you use Supabase, that means Row Level Security policies on every table that holds user data. If you use Firebase, it means Firestore rules that deny reads and writes by default and only allow them for authenticated, authorized users. These two layers, API auth and database auth, should be independently secure so that a failure in one does not expose everything.

Move on to secrets and payment integrations. Search your entire codebase (including git history) for any API key, database URL, or webhook secret that appears outside of environment variables. Then verify your payment webhook endpoints: Stripe and LemonSqueezy both send a signature header with every webhook event, and your handler must verify that signature before processing the payload. Without verification, an attacker can forge payment events to grant themselves free access or manipulate subscription states. Finally, check your CORS policy and Content Security Policy headers. Overly permissive CORS settings can let malicious sites make authenticated requests on behalf of your users.

The remaining items on the checklist cover operational basics: enable HTTPS everywhere (Vercel and Railway do this by default, but custom domains need verification), set secure cookie flags (HttpOnly, SameSite=Strict, Secure), add rate limiting to login and signup endpoints, configure error handling to never leak stack traces or internal paths to the client, and set up monitoring so you know when something goes wrong. None of these steps require deep security expertise. They are concrete, mechanical checks that take an afternoon to complete and prevent the vast majority of real-world attacks targeting early-stage SaaS products.