I built a SaaS around one frustrating moment every freelancer knows

You know that moment when a client says "looks great, just one small tweak" - and three weeks later you've done 40% more work than you quoted?

I spent years as a freelancer thinking the solution was better contracts or clearer proposals. It wasn't. The problem was structural: once work starts flowing, there's no natural point where payment kicks in until the end.

So I built a tool around one simple mechanic: stage locking.

Break project into stages. Each stage has a price. Client can't access the next stage until they pay for the current one. That's the whole product.

Why I think this works as a microSaaS:

The problem is universal but underserved. Every freelancer deals with scope creep and payment delays. But existing tools are either invoicing software (pay after work is done) or massive all-in-one platforms that try to do everything.

Nobody was doing payment-as-workflow. So that's the gap I went for.

What I learned building it:

The feature I thought would be the sell - automated reminders - turned out to be secondary. The stage locking is what clicks with people. When I explain it, freelancers immediately get it because they've all lived the problem.

Simple mechanic, strong emotional hook. That combination seems to work better than a feature list.

The boring stuff:

Stack is React, Supabase, Stripe Connect, Vercel. Built it with AI tools as a non-technical founder. Zero transaction fees (flat subscription) because taking a cut of payments felt like the wrong model for this audience.

Still early - just launched and onboarding beta users. No idea if it'll become a real business or stay a side project, but the validation so far has been interesting.

The site is milestage.com if anyone wants to poke around.

Curious if others here have built around a single core mechanic like this, or if you've found more success going feature-heavy from the start. Still figuring out where the line is between "focused" and "too simple."