If you sell on OnBuy and run ERPNext, the two systems don't talk. New OnBuy orders get keyed into ERPNext by hand (or copied from a CSV export), stock counts drift between the marketplace and your Bin balances, and tracking numbers are pasted into two places. When a boxing week rush lands you get oversells, cancelled orders, and OnBuy performance-metric penalties — and ERPNext core has no OnBuy integration to fall back on, because OnBuy simply isn't a supported channel out of the box. This is the gap ECOSIRE closes.

We build a proper Frappe app — installed on your own ERPNext v15 or v16 bench — not a spreadsheet macro or a brittle Zapier chain. The app ships its own module with dedicated DocTypes: an OnBuy Settings single DocType holding your API credentials and channel defaults, an OnBuy Order / channel-order mapping so every marketplace order links back to the ERPNext Sales Order and Delivery Note it created, an OnBuy Listing DocType tying each OnBuy SKU/OPC to an ERPNext Item, and a OnBuy Sync Log for full auditability. Credentials and secrets are stored using Frappe's encrypted password fields, and access is governed by a purpose-built role profile so warehouse staff, finance, and admins each see only what they should.

Order ingestion runs on Frappe scheduler_events (configurable cron, typically every few minutes) via whitelisted server-side methods that call the OnBuy API, deduplicate against already-imported orders, and create Sales Order documents with the correct customer, currency (GBP), tax template and item lines. Inventory and price sync is two-way: hooks.py doc events on Stock Ledger Entry / Bin and on Item Price push updated available quantity and prices back to OnBuy, while inbound changes are reconciled on schedule — with buffer/ring-fence rules so you never publish more stock than you can safely fulfil. When you ship, a doc event on Delivery Note submission writes the carrier and tracking number back to the OnBuy order. Settlement files and payout data are imported and reconciled against ERPNext, mapping OnBuy commission, fees and payouts to the right accounts so finance can tie every payout to its orders. Optional client scripts add "Sync now" buttons and status indicators directly on the relevant ERPNext forms, and everything is exposed through the Frappe REST API for your other tooling.

Because this is build-to-order, we start from your actual OnBuy account, catalogue structure and ERPNext configuration rather than a one-size-fits-all binary. After a short scoping call we confirm exact field mappings, tax handling, warehouse/stock rules and edge cases, then build, test on a staging bench, run UAT with you, and deploy to production. Typical delivery is 2–4 weeks from confirmed scope. You receive the full source in a git repository you own, technical and user documentation, a training session, and a post-go-live support window — no lock-in, no black box.