How to Secure a SaaS Before Launch

Launching a SaaS means asking strangers to trust your code with accounts, data, money, and sometimes decisions that affect their business. A last-minute scan is useful, but it is not a security plan. The useful question is: which paths can hurt the user or the business, and have they been tested before launch?

This is the practical review I use before a small product goes live. It is intentionally focused on the surfaces that create the most risk for an early SaaS.

1. Start with trust boundaries

Map who can do what before looking at tools. A regular user, an administrator, a support operator, a webhook, and a background worker should not all have the same authority. Write down the boundary around each role and test the boundary directly.

• Can a user read another user's record by changing an ID?
• Can a client-side flag unlock a paid feature?
• Can a support or admin route be reached with a normal account?
• Can a background job be triggered with untrusted input?

2. Protect authentication

Use short-lived access tokens, carefully rotated refresh tokens, strong password-reset flows, and explicit authorization checks. Authentication proves who someone is; authorization decides whether that person may perform this action. The second check is where many real bugs live.

3. Treat payments as state

Never let the browser decide whether a subscription is active. Verify webhook signatures, make handlers idempotent, and let the server own entitlements. Test successful payment, delayed webhook delivery, cancellation, refund, duplicate events, and failed renewal paths.

4. Keep secrets and dependencies boring

Secrets belong in the platform secret store, not in the repository, client bundle, screenshots, or chat history. Lock dependencies, scan them, and have a rotation path for the moment a credential is exposed. A secret that might have leaked is a secret to rotate.

5. Know how you will recover

Monitoring is not just a dashboard. Know what alerts, who receives them, how to revoke access, how to pause a risky integration, and how to restore data. A launch is safer when the team knows what to do after the first surprise.