Its a SaaS web app so feature flags are stored in the DB for easing flipping by biz people so they can rollout features w/o having to involve engineers. Simple homegrown solution of a table, name of feature flag and a boolean, corresponding object with handy methods and a simple UI. Feature flags are commits as blocks of feature flagged code. There might be a dozen or two at a time so querying an indexed DB table with < 50 rows is not an issue.

Blocks of code around the intended feature flag find the feature flag boolean and do whatever they are supposed to do. If a feature flag is not found it defaults to false/off. Later on after features are rolled out and have become the default, an engineer removes the FF code, related tests, and DB row.

I don't see how a tool/SaaS could be any better for this scenario. There is a DB dependency but honestly if the DB isn't available then shit is on fire in a very bad way and I don't care about feature flags in that moment.

Other options could be ENV variables loaded at app startup, this can get unwieldly though if you have a lot of them and requires an engineer to be involved. Putting feature flags in an external system seems like purposely introducing more failure modes to your app.