A reseller inventory app, and what it has to get right

Most inventory software is built for a shop that holds forty identical units of one product. Reselling is the opposite: forty different things, each bought once, each with its own cost and its own story. That difference decides whether an app helps you or fights you, and it shows up in three places.

One row per physical unit

A warehouse system stores "Nintendo Wii, quantity 5". That is the right shape when the five are interchangeable and cost the same. Yours did not: three came out of a house clearance at an average of four pounds each, one was eighteen from a car boot sale, one was free with something else.

So when one sells for forty, "what did I make?" has five different answers, and a quantity field cannot tell you which. Every unit needs its own row, with its own cost, its own condition and its own days in stock. That is the only arrangement in which "mark this one sold" means something specific.

It matters for the boring cases too. One of the five has a cracked hinge and sells for twelve, not forty. One has been sitting for eleven months. A quantity field averages all of that into a number that describes none of them.

Cost belongs to the purchase, not the item

You rarely buy one thing. You buy a box for sixty pounds and it turns out to hold nine sellable items and some rubbish. There is no honest per-item price in that transaction until you decide how to split it.

Apps that put a cost field on the item force you to invent that number at the moment you are typing, usually by dividing by nine and moving on. Then you sell the one good thing in the box for eighty and the app tells you the box made a loss on eight items and a fortune on one, which is arithmetic rather than information.

Recording the purchase as the event it was, and hanging items off it, keeps the real shape: sixty pounds went out, these nine things came in, and the purchase is in profit once eighty has come back. Per-item splits are a view you can take afterwards, not a decision you should be forced into at the till.

The failure case is worse than imprecision. An item with no purchase attached has no cost at all, so whatever it sells for is booked as pure profit. A month of those and your margin looks wonderful and is fiction.

Profit means after fees, and fees are not a guess

Sale price minus purchase price is not profit. Between them sit the platform's cut, the postage you paid, the packaging, the petrol to the pickup, and sometimes a partial refund months later.

Fee structures differ by marketplace, by category and by country, and they change. An app that quietly applies a built-in percentage will be wrong for somebody, and you will not be told which somebody. Recording what actually left your account is slower by a few seconds and correct permanently.

The other number worth having is return on what you spent, measured against the purchase price rather than against every cost you can think of. It answers a question you can act on: was that sixty pounds well spent, and should I buy the next box like it?

What Flippo does with all that

Flippo records purchases, splits them into individual units, tracks where each one is listed, and works out profit, ROI, days on hand and sell-through per item and per platform. You can photograph a haul and let it identify the items and estimate what they resell for, which is the part that makes cataloguing tolerable.

It runs in any browser, including a phone browser. An iPhone app is in review with Apple and an app for ChatGPT is in review with OpenAI; neither is live yet.

When it is the wrong tool

Worth saying before you spend anything.

If your problem is listing, not accounting. Flippo does not post listings for you or push one item to five marketplaces. If the hours are going on writing the same description repeatedly, a crosslisting tool solves more of your day than this does. We wrote about where those tools fit and what they cost.

If a spreadsheet is still coping. It often is, for longer than people admit. The honest signals that it has stopped are in this piece: per-item questions you cannot answer, and receipts living somewhere other than the numbers.

If you want a permanently free tool. Flippo is paid, with a 14-day trial of the full app. Several competitors run a free tier with row limits. If cost is the deciding factor, they are a reasonable place to start, and this comparison lists what each one charges.