Overview

Build ERP is a construction operations platform that began as the internal system of a US construction subcontractor and has since been reshaped into a multi-tenant SaaS product. It keeps a project's paperwork, field reporting, purchasing and billing in one place and connects them to the accounting system, so the office stops re-keying the same numbers into several tools.

My role

I worked on Build ERP as a developer on the team that builds it. The copies of the code I have are source snapshots without commit history, so this page describes the platform as a whole rather than attributing individual modules to me.

What it does

• Project documents: RFIs, submittals, transmittals, drawings, specifications and closeout, organised per project.
• Field reporting: daily logs, equipment logs, material tracking and inventory.
• Cost and billing: estimating, change orders, a purchase-order log, bill tracking, and AIA-style pay applications with retainage tracking.
• People: a company and contact directory, plus HR modules for employee profiles, leave and an internal bulletin.
• Integrations: QuickBooks Online accounting sync, and imports of projects, RFIs, daily logs, drawings and pay applications from Procore.
• SaaS layer: self-serve trial signup, workspaces, invitations, roles, per-module feature flags and Stripe subscriptions, fronted by a React landing page.

How it's built

The backend is a Django 5 monolith with one app per module, server-rendered with Django templates and django-cotton components, and Google sign-in through django-allauth. Every authenticated request passes a tenant-context middleware that resolves the active workspace, then an onboarding gate. Permissions have three layers: organisation role, which projects a member can see, and module-level permission packs. QuickBooks data lives in a separate PostgreSQL database behind a Django database router, and the landing page is a React 19, Vite and Tailwind build served by Django.

Highlights

• Incremental QuickBooks sync: bills, vendors, accounts, invoices, payments, journal entries and other entities are pulled by a last-updated cursor or by change data capture (including deletions), transformed, and bulk-upserted one row per line.
• Webhook-driven billing: Stripe webhooks are the source of truth for subscription state, with an idempotent event log, an out-of-order guard on event timestamps, and status codes chosen so Stripe retries only transient failures.
• Fail-closed tenancy: a request without a resolved workspace never reaches an app view; browsers are sent to a workspace picker and AJAX calls get a machine-readable JSON reason instead.