Fashion, footwear, and apparel retail lives and dies by the size/color grid. A single style ships in dozens of variants, and ERPNext models each one as a distinct Item Variant under an Item Template with has_variants and its own Item Attributes. That data model is correct, but the native UI was never designed for a merchandiser thinking in matrices: adding a new season means creating variants one at a time, receiving stock means hunting through a flat item list, and the standard POS Awesomebar makes a cashier type to disambiguate "black / M" from "black / L" mid-queue. ERPNext core gives you the ledger; it does not give you the grid. That gap is where apparel retailers stall, resort to spreadsheets, or mis-count inventory at the variant level.

We build a proper Frappe app — a versioned, bench get-app-installable module, not a pile of customizations — that layers matrix merchandising and a fashion POS on top of your existing ERPNext without forking core. The heart is a size/color matrix grid: a client-scripted UI where a merchandiser picks a Style/Item Template and enters quantities, prices, or barcodes across a rows-by-columns grid (for example size down the side, color across the top), and a whitelisted server method (frappe.whitelist()) fans that grid out into the correct Item Variants, Item Barcodes, and stock or price rows in one transaction. Barcode-per-variant generation is wired through a hooks.py doc event so every variant that comes into existence gets a scannable code (EAN-13 / Code128) attached to its Item Barcode child table, and the POS is extended so a scan resolves straight to the exact variant line — no cashier lookup. A Matrix Stock View DocType and Query Report roll Bin quantities back up into the same grid across every Warehouse/store, so a buyer sees the full size curve per store at a glance and spots the broken sizes before they become markdowns. Season/collection and style attributes are added as custom fields and a Collection DocType so you can merchandise, filter, and report by season the way the industry actually works.

Everything is built to ERPNext conventions so it survives upgrades and audits: real DocTypes with fixtures, Server Scripts and app hooks rather than hand-edits, Client Scripts for the grid UX, permissions expressed through Role Profiles and DocType permissions (a cashier role sees POS, a merchandiser role sees the matrix, a buyer sees the stock view), and Scheduler Events for any nightly reconciliation such as re-syncing barcodes or flagging negative variant stock. The matrix grid and stock view are also reachable over the Frappe REST API and custom whitelisted endpoints, so a Shopify/marketplace connector or a mobile stock-count tool can read and write the same variant data. It targets Frappe/ERPNext v15 and v16.

Because this is build-to-order, nothing here is a one-click marketplace download. After a short scoping call we confirm your exact attribute structure (your real size runs, color libraries, and season taxonomy), your store/warehouse layout, and your POS workflow, then quote a fixed scope. We build on a staging bench, hand you the code for User Acceptance Testing, and — on your sign-off — install into production with a documented rollback path. Typical delivery is 2 to 4 weeks from confirmed scope, depending on how many attributes, stores, and integrations are in play. You receive the source, the git repository, technical and user documentation, a training session, and a post-go-live support window.