ERPNext ships a basic Subscription DocType, but SaaS and membership businesses quickly hit its ceiling. Native subscriptions generate invoices on a schedule and stop there: there is no mandate capture, no automatic payment collection, no dunning cascade when a card fails, no mid-cycle proration when a customer upgrades, and no metered usage. Teams end up chasing failed payments in spreadsheets, manually raising credit notes for plan changes, and watching involuntary churn eat into MRR. The moment you need eMandate, SEPA, or stored-card collections with retries, ERPNext core runs out of road.

We build a proper Frappe app (its own module, installed via bench get-app and bench install-app) that layers a real billing engine onto ERPNext without forking core. New DocTypes model the domain cleanly: Billing Plan (interval, price, trial, proration rule), Subscription Mandate (gateway token, mandate reference, status, scheme — card/UPI eMandate/SEPA), Dunning Cascade (ordered retry steps with delays and actions), and Usage Record for metered lines. hooks.py doc events on Sales Invoice and Payment Entry keep ERPNext ledgers authoritative — every collection still posts through standard accounting, so your GL, AR aging, and tax reports stay correct.

Collection and retries run on Frappe's scheduler. Scheduler events (hourly and daily) walk due subscriptions, capture against the stored mandate through your gateway, and on failure advance the Dunning Cascade — retry with backoff, send templated reminders, then suspend or cancel per policy. Proration is computed server-side when a plan changes mid-cycle, raising the correct debit/credit adjustment automatically. Gateway calls go through whitelisted server-side methods (@frappe.whitelist()) and a webhook endpoint that validates signatures, so payment status is reconciled inbound as well as outbound. Client Scripts add the subscription cockpit to the customer and Subscription forms; role profiles and permission rules keep billing operators, finance, and read-only support scoped correctly. Everything is reachable over the Frappe REST API for your app or portal, and the build targets Frappe/ERPNext v15 and v16.

Because this is build-to-order, nothing is pre-listed for instant download. We start from your actual plans, gateways, and dunning policy, agree the scope, then build against it. Typical delivery is 2-4 weeks from confirmed scope. You get the installable source for your version, a staging UAT pass with a rollback plan, installation and configuration on your bench, technical and user documentation, a training session, and a post-go-live support window — plus the git repository handed over so your team owns the code.