Why I Built MultiTally

If you sell on Amazon, Walmart, or Shopify, there's a good chance you don't actually know how much money you're making. Not really. You see your sales dashboard showing strong revenue numbers, but the “your sales” number on the marketplace dashboard is not your profit. It's the starting point of a long subtraction problem — referral fees, FBA fulfillment charges, storage costs, advertising spend, return processing, payment gateway fees. A product that looks like 30% margin is often closer to 8% once you account for all of it.

Most sellers who try to track real profitability end up in spreadsheets. And not tidy little workbooks — 40-tab monstrosities with VLOOKUP chains that break every time Amazon changes a column name in their settlement reports. Hours of manual data entry every month, and the numbers are still approximate because the spreadsheet can't keep up with fee changes, COGS updates, or the complexity of selling across multiple marketplaces simultaneously. It's a problem that gets worse the more successful you become.

Existing SaaS tools don't solve it either. Most cover one marketplace at best, and the ones that try to calculate profit are estimating fees based on category averages instead of using the actual fee data sitting right there in settlement reports. As an accountant, that distinction matters. Estimates are fine for projections. They're not fine for P&L statements. I built MultiTally because sellers deserve real numbers — the kind an accountant would stand behind.

Look at the ecommerce tools landscape and you'll find plenty of options — for different problems. Jungle Scout and Helium 10 are product research tools. They help you find products to sell, not figure out whether you're actually making money on the ones you already sell. Sellerboard does solid per-SKU profitability — but only for Amazon. If you also sell on Shopify or Walmart, you need a separate tool, a separate login, and a separate mental model for how each one calculates profit. Good luck comparing margins across channels.

On the Shopify side, Triple Whale and Lifetimely focus heavily on DTC brands and ad attribution. They're built for a different seller profile — someone spending $50K/month on Facebook ads who needs to know their customer acquisition cost. That's not the same problem as “Amazon charged me 17 different fee types last month and I don't know which of my 200 SKUs are actually profitable.”

Nobody builds for the multi-channel seller who needs to compare profitability across Amazon, Walmart, and Shopify in one dashboard. That's the gap. And the reason the gap exists is because it's genuinely hard. Each marketplace has its own fee structure, its own settlement format, its own API quirks. Amazon alone has over 50 distinct fee types. Walmart uses a completely different referral fee model. Shopify charges processing fees that vary by plan and payment gateway. Normalizing all of that into a single, accurate P&L requires someone who understands both the accounting and the engineering. That's what I decided to build.

MultiTally maps all 114 fee types across Amazon, Walmart, and Shopify to a single canonical data model. That means every referral fee, fulfillment charge, storage cost, advertising deduction, return processing fee, and payment processing fee gets categorized the same way regardless of which marketplace it came from. We don't estimate based on category averages — we use your actual settlement data. The same source your marketplace uses to calculate your payout is the same source we use to calculate your profit.

The result is a true per-SKU P&L that shows every fee broken down, every cost accounted for, and a net profit number you can actually trust. Sell the same product on Amazon and Shopify? MultiTally shows you the profitability side-by-side so you can see exactly where you make more per unit and why. Maybe Amazon's referral fee is eating your margin but the volume makes up for it. Maybe your Shopify store has lower fees but higher return rates. Those are the insights that change how you run your business.

COGS management is built in with temporal date ranges, because costs change over time and your profit calculations need to reflect that. If your supplier raised prices in February, your January margins should use January costs and your March margins should use March costs. That's how accounting works, and that's how MultiTally works. I built this tool the way I'd build a set of books for a client — because that's exactly what it is. A proper financial record for a business that happens to sell on multiple marketplaces.

Shopify is live right now. You can connect your store, and MultiTally will pull in your orders, products, and transaction fees automatically. Amazon and Walmart integrations are built and entering final testing — both will be live in Q2 2026. If you want to get a feel for the product before connecting anything, the Marketplace Simulator is free and doesn't require an account. Plug in a product's details and see how profitability compares across all three marketplaces with real fee schedules.

We're also running a founding member program: the first 50 users get 50% off their subscription for life. Not a temporary discount — a permanent rate lock as a thank you for being early. If cross-marketplace profitability is a problem you deal with, this is the cheapest it will ever be to solve it.

The data foundation is solid. What comes next is making that data work harder for you. AI-powered margin alerts that don't just tell you your profit dropped — they explain why. Monthly P&L reports generated automatically with charts and key takeaways. Natural language queries so you can ask “which products lost margin this month?” and get a real answer from your own data. And a Chrome extension for quick profitability checks while you're browsing product listings.

The goal is simple: make every ecommerce seller as financially informed as they'd be if they had their own accountant looking at the numbers every day. I happen to be that accountant, and I happen to write code. MultiTally is what comes out of that combination.