--- title: What this app does summary: > Mossery is the app that keeps track of every physical thing the business owns, from the moment it is ordered to the moment it ships. It covers buying, receiving, storing, making, selling, fulfilling and updating your online channels. Every stock movement is written to a permanent ledger, so any number on any screen can be traced back to the event that produced it. type: concept group: overview permission: null prerequisites: [] related: - /help/fulfil/when-stock-actually-moves - /help/store/the-stock-ledger - /help/reference/glossary last_updated: 2026-08-07 --- **This app keeps track of every physical thing the business owns, and every event that changed it.** Boxes arrive from suppliers, sit on shelves, get built into other things, get sold, and leave again. Somebody has to know how many of each are where, right now, and be able to explain how that number came about. That is the whole job. This page covers: - [What it is for](#what-it-is-for) - [The seven stages](#the-seven-stages) - [Every number traces to an event](#every-number-traces-to-an-event) - [Stock leaves at one moment](#stock-leaves-at-one-moment) - [What it is not](#what-it-is-not) - [Where to start](#where-to-start) ## What it is for It replaces the commercial inventory system the business used to rent. That system was expensive, and worse, it was not trustworthy: numbers moved without an explanation anyone could find, stock got reserved by orders that no longer existed, and reconciling it took days that nobody had. Replacing it was about accuracy first and cost second. So this app is built around a single promise. Every number is traceable. If a figure looks wrong, you can open its history and find the event that changed it, with a date, a quantity, a location and a person. There is no state that "just happened". It is an internal working tool, used daily by the people who keep stock accurate and orders moving. It is not a shop, and customers never see it. ## The seven stages Stock moves through the business in one direction, and the app is organised the same way. | Stage | What happens | Start here | | --- | --- | --- | | **1. Buy** | Deciding what to order, and ordering it | [Buy](/help/buy) | | **2. Receive** | Goods arrive and go on the books | [Receive](/help/receive) | | **3. Store** | Where stock lives, and counting it | [Store](/help/store) | | **4. Make** | Parts become finished goods | [Make](/help/make) | | **5. Sell** | Orders come in from your channels | [Sell](/help/sell) | | **6. Fulfil** | Stock leaves. Only here | [Fulfil](/help/fulfil) | | **7. Sync** | Channels get the new number | [Sync](/help/sync) | Not every business uses all seven. A business that buys finished goods and resells them never touches Make. The order still holds: nothing reaches stage 5 that has not been through stage 2. To walk the stages one at a time, with the numbers that change at each step, use the [step-by-step explorer](/help/overview). ## Every number traces to an event The app keeps two things, and only one of them is the truth. - **The ledger** is a permanent list of movements. Twenty units received here on Tuesday. Three written off there on Friday. Entries are added, never edited and never deleted. - **The stock figure** you see on screen is calculated from that list. It is a convenience, not a record. Delete it and it could be rebuilt from the ledger exactly. This ordering is the reason a mistake never becomes a mystery. Correcting an error means adding an opposing entry, so both the error and the correction stay visible. Nobody can quietly retype a number into being right. It also means the question to ask about a suspicious figure is never "what is the number". It is "which event last changed it", and the answer is always on the product's movement history. See [The stock ledger](/help/store/the-stock-ledger). ## Stock leaves at one moment Stock is deducted at fulfilment, and nowhere else. Placing an order does not move stock. Neither does picking it, nor packing it. Those steps allocate units, which lowers what you can still sell while leaving what you physically hold untouched. Only shipping consumes them. The alternative, deducting when an order is created, sounds tidier and is the source of a whole class of ghost numbers: cancelled orders, failed payments, duplicated carts and abandoned checkouts all have to be reversed, and a reversal that fails silently leaves stock the app thinks it does not have. Deducting once, at the moment goods physically leave, removes the entire problem. See [When stock actually moves](/help/fulfil/when-stock-actually-moves). ## What it is not Four honest limits, so nothing here is a surprise later. - **It is not the storefront.** Your online stores hold their own stock numbers, which are copies of these ones, pushed out after the fact. When the two disagree, this app is the original. - **It is not accounting.** It knows what stock cost and what it is worth; invoices, ledgers and tax live in your accounting system. - **It is not a warehouse robot.** It records what people did. If the shelf and the app disagree, the fix is a physical count, not a clever calculation. - **It is not customer-facing.** No shopper ever opens it. ## Where to start Pick the door that matches why you are here. - **You do a job every day and want the steps.** Go to the stage you work in from the table above. - **You want to understand the model.** Read [the stock ledger](/help/store/the-stock-ledger), then [when stock actually moves](/help/fulfil/when-stock-actually-moves). Those two carry most of the design. - **A number looks wrong.** Start at [Something looks wrong](/help/wrong). - **A word on a screen means nothing to you.** The [glossary](/help/reference/glossary) has one or two sentences on each. ## Explore **Walk the seven stages.** An interactive tour of what changes at each step. [Learn more →](/help/overview) **When stock actually moves.** Why an order does not reduce your stock, and fulfilment does. [Learn more →](/help/fulfil/when-stock-actually-moves) **The stock ledger.** The permanent record every number on every screen is derived from. [Learn more →](/help/store/the-stock-ledger)