OPERATORSTACK

FOR ECOMMERCE OPERATORS

Plenty of stores lose money on every sale. The owners find out months too late.

Margin Killer is an AI agent that audits your real margin in 90 seconds. Every fee. Every dispute. Every refund. Your true breakeven CPA.

Built running my own live store · Battle-tested across 300+ real product audits

45-second demo: Margin Killer runs a full store audit, start to finish

45-second demo: a full store audit, start to finish.

Instant delivery · Works with Claude · All sales final

Before

The dashboard said +$2.24 per order.

After

Margin Killer found −$1.87. Every fee, itemized, in 90 seconds.

Same store. Same numbers. One audit.

The 3 numbers nobody calculates

Your dashboard shows revenue. These three decide if you keep any of it.

4–6%

The real payment-fee stack

You plan for 2.9% + 30¢. On a typical $40 order, the real stack often lands at 4–6% once currency conversion, payout and app fees pile on. That can be double what you budgeted.

$25+

What one dispute really costs

A chargeback takes the product, the shipping, and the ad spend that bought the order. Then the processor adds its standard $15–$25 dispute fee on top. One dispute can erase the profit of several clean orders.

?

Your real breakeven CPA

Most owners set their target CPA from gross margin. Add fees, refunds, and disputes, and the real ceiling is often meaningfully lower than the number you're using. Scale ads against the wrong number and you scale the loss.

Margin Killer calculates all three from your store's numbers. In one run. Here's what that looks like.

See what it catches

Real output from the agent. Your numbers in, your economics out.

Margin Killer output: full fee breakdown for one order
Every fee on one screen. No more "roughly 30% margin" guesses.
Margin Killer output: worst, median and best case scenarios
Worst, median, best case. Know your downside before you scale spend.
Margin Killer output: true breakeven CPA calculation
Your true breakeven CPA. The one number your ad account has to beat.

What you get for €17

  • The Margin Killer agent file. Install it in Claude once. Run it on any store, any time.
  • Setup guide. Five minutes. A screenshot for every step. No code.
  • Three worked examples. Dropshipping, print-on-demand, and a branded store — audited end to end.
  • Full prompt source. See exactly how it thinks. Edit it if you want. Nothing hidden.
  • Free v1 updates. Improvements land in your inbox. No re-buying.

Instant delivery · Works with Claude · All sales final

Who this is for

For you if…

  • You run a store with real orders and real ad spend.
  • You buy traffic and need a CPA target you can trust.
  • You want the true number, even when it stings.
  • You can paste numbers into a chat. That's the whole skill requirement.

Not for you if…

  • You're looking for a magic winning-product button. This isn't it.
  • You want income promises. We don't make them.
  • You have no store and no numbers yet.
  • You want a course. This is a tool, not content.

Still here? You're who this was built for.

Why this exists

Javi — the operator behind Operatorstack

I run my own store. I built Margin Killer because I kept finding fees after the money was already gone. Now it's the audit I run before scaling anything. No guru team. No rented Lamborghini. Just the tool I needed.

— Javi Pérez · @javiperezbuilds

If you've ever found a fee after the money was gone, you already know what this is worth.

What €17 replaces

An hour of a freelance media buyer's time $75–150+
The spreadsheet you keep meaning to build — and it still misses fee lines ~6 hours
Margin Killer — 90 seconds, unlimited runs €17

Instant delivery · Works with Claude · All sales final

Questions, answered

How is it delivered?

Instantly. After checkout you get an email with the agent file and the setup guide. Five minutes later you're running your first audit.

What do I need?

A paid Claude plan (Pro) — that's where the agent runs. The setup guide shows exactly where to install it. No other tools. No code.

Does it work for my niche?

Yes. It audits unit economics: COGS, fees, disputes, refunds, breakeven CPA. Every store has those, in every niche.

What's the sales policy?

All sales are final. This is digital content delivered instantly — watch the demo above, read what's included, and check the "Not for you if" list before buying. If your download fails or the file is defective, email us and we fix it or replace it.

Is this a course?

No. It's a tool. You install it, feed it your numbers, and it gives you answers. Nobody talks at you for six hours.

Are updates included?

Yes. All v1 updates are free and land in your inbox.

One question left: does your store actually make money?

Plenty of stores lose money on every sale. Find out today if yours is one of them.

90 seconds. Your real margin, your real breakeven CPA, your worst case.

Instant delivery · Works with Claude · All sales final