---
title: "Build an App with AI Agent"
space: "Integrations"
url: "https://integrations.frappe.cloud/building-custom-gateway"
updated: "2026-09-10"
---

Payment Core includes an agent guide that helps developers research, build, test, and document a new payment-provider app for Frappe and ERPNext.

  The complete instructions are maintained in [`AGENTS.md`](https://github.com/aerele/payment-core/blob/develop/AGENTS.md).

  > Payment Core remains provider-neutral. Credentials, API clients, checkout pages, webhooks, branding, and provider-specific logic
  are created in a separate provider app.

  ## Demo

  ![Building a payment provider app with Payment Core](/files/phonepe-complete-merged.mp4)

  ## Supported Development Tools

  - **Codex** and **Cursor** automatically discover `AGENTS.md`.
  - For **Claude Code**, explicitly ask it to read and follow `apps/payment_core/AGENTS.md`.

  ## Before You Start

  Use a Frappe Bench containing:

  - Frappe
  - ERPNext
  - Payment Core
  - A local development site for testing

  Payment Core supports Frappe and ERPNext from `version-16` through `develop`.