Custom ERP Development for US Companies, Built on a Proven Core

When custom ERP development makes sense

An ERP is the system where sales, purchasing, inventory, production, finance and people agree on the same numbers. Custom ERP development is the right call when that system has to follow how your business actually works, not the other way round.

In our experience it pays off in four situations:

• Your workflows are your advantage. Unusual quoting, made-to-order production, consignment or service contracts that a package handles only through workarounds.
• The package needs too much customization. When a NetSuite, Odoo or SAP Business One implementation needs so many custom scripts that every upgrade becomes a project.
• Per-user costs scale badly. Subscription seats for warehouse, shop-floor and field staff can cost more over a few years than a system you own.
• Your data is spread across tools. A CRM, a spreadsheet for stock, a separate POS and an accounting package that nobody reconciles in real time.

If none of these apply, buy a package. We will tell you that in the first call.

Starting from a proven core, not a blank page

RAIN Design Studio is a senior studio in Casablanca, Morocco, working remotely with US companies. What makes our custom ERP solutions different is that we did not learn ERP on client budgets. We built our own.

RIVER ERP is a self-hosted business system on Laravel 13, Vue 3 and Tailwind CSS v4, with:

• 23 activatable modules, 12 suites and 154 screens, from CRM and sales documents to inventory, production, POS, treasury, accounting and HR
• 16 business document types, so a quote becomes an order, a delivery note and an invoice without re-keying
• Real-time updates over WebSockets, role-based permissions and an activity log
• Adapters for 18 AI providers, including local models for data that should not leave your servers
• One codebase that ships as a web app, PWA, iOS and Android wrappers, and a desktop app for macOS, Windows and Linux

Starting from that experience means the unglamorous parts, such as permissions, numbering, document flows, audit trails and POS, are solved problems. Your budget goes on the workflows that are specific to you. Our custom ERP development service covers the core in more detail.

What a US ERP needs that a Moroccan one does not

RIVER ERP was built Morocco-first: Moroccan e-invoicing, the Moroccan chart of accounts and local tax identifiers. A US build replaces that localization layer, and we scope it explicitly:

• Chart of accounts and reporting aligned with how your accountant closes the books under US GAAP.
• Sales tax: there is no VAT in the US, and state and local sales tax rules vary. Since the Supreme Court’s 2018 Wayfair decision, remote sellers can have obligations in states where they have no physical presence. For multi-state sellers we usually integrate a dedicated sales tax service rather than maintain rate tables in the ERP.
• Accounting integration: many US companies keep QuickBooks or another accounting package for the general ledger and let the ERP handle operations, syncing invoices, bills and payments.
• Payroll: US payroll is best left to a specialist provider; we integrate it rather than rebuild it.
• Payments and channels: Stripe, ACH, Shopify and marketplaces connect through their APIs and webhooks.

None of this is legal or tax advice; your accountant decides the rules, and we implement them.

Custom ERP software vs off-the-shelf

Criterion	NetSuite	Odoo	SAP Business One	Custom ERP on a proven core (RAIN)
Fit to your workflows	Configurable, scripts for the rest	Configurable, custom modules for the rest	Configurable via partners	Built around your workflows
Licensing model	Subscription, typically per user	Community edition or paid subscription	License or subscription via partners	Fixed-scope build from $10,000; no per-seat fees by default
Implementation	Partner or vendor services	Partner or in-house	Partner	RAIN designs and builds, one senior lead
Hosting	Vendor cloud	Vendor cloud or self-hosted	Partner cloud or on-premises	Self-hosted on servers you control, or a cloud of your choice
Upgrades	Vendor schedule	Version migrations	Partner-led	On your schedule, in your repository
Best fit	Standard processes at scale	Budget-conscious, standard processes	Partner-supported SMBs	Processes that are your advantage

Packages are good software. The question is whether your business fits them, or has to be bent to fit. If your ERP is one part of a wider platform, such as a customer portal or a field app, our page on custom software development for US companies covers that broader work.

Proof: vertical ERP and migration work

GoldERP: rebuilding a legacy ERP without losing a feature

GoldERP is a vertical ERP for gold and jewelry workshops, tracking raw gold, silver and stones through workers to finished pieces and sales split across cash, checks and customer credit. We rebuilt it from a 2020 CodeIgniter application into Laravel 13 and Filament 4: 15 workflow screens, 11 history pages and 5 reports, with 41 test files running in CI.

The migration discipline is the part US buyers should care about. A legacy importer and a parity harness run the old system’s formulas against the new ones in CI, and a parity matrix accounts for every legacy feature: 90 done, 24 deliberately dropped, 0 missing. The rebuild is feature-complete against the legacy system; production cutover is the next step.

ERPStore: billing and CRM at the core

ERPStore is our subscription store, billing and CRM platform with 10 payment methods, 76 API endpoints and a client portal in 32 languages. Its upgrade was validated on a real database of 1,023 users, 354 orders and 483 payments, without data loss. It is licensed per domain with signed license keys, the same approach we use for self-hosted ERP builds.

How a custom ERP project runs

1. Free 15-minute call to understand your operation and what is not working today.
2. Discovery: process mapping with the people who do the work, a data audit and a written scope with a fixed price.
3. Design of the key screens and document flows in Figma, reviewed with your team.
4. Build in two-week increments, with a working release and a Loom walkthrough every Friday.
5. Migration and parallel run: import, reconcile balances, and switch over only when the numbers match.
6. Support on a retainer, or a handover to your own team.

A custom platform typically takes 8–16 weeks, with a focused first release at the shorter end.

Working with a US company from Casablanca

Casablanca is 5–6 hours ahead of the US East Coast and 8–9 hours ahead of the West Coast, so East Coast teams share around four hours of their morning with us, and West Coast projects run async-first. We have no US office; discovery workshops on site can be arranged for larger projects. We invoice in US dollars, sign your NDA, and agree ownership of custom modules and the core in writing before kick-off.

Talk to us about your ERP

Book a free 15-minute call or write to rain@mrzakaria.com. Tell us what your team runs on today, where the numbers stop agreeing, and what you have already tried. Projects start at $10,000, retainers at $7,500 per month, and we will tell you honestly whether a custom ERP or a package is the better answer.