The Modular ERP Buyer's Guide

This is the long version of what to look for in an ERP. Use it with a vendor in the room: each section ends with questions you can ask and what a good answer sounds like.

Who this is for

Businesses that have outgrown spreadsheets and separate tools but do not need a multi-year enterprise programme. Typically 20 to a few hundred employees, with sales, purchasing, stock, payroll and invoicing as daily work, where reconciling between systems has become a measurable cost.

If you are weighing the largest enterprise suites with a dedicated implementation team, the architecture and security sections still apply. The rollout and cost sections will look different.

Part 1. Architecture

1.1 Shared data, or shared login

Modular can mean pricing or architecture (the difference). Test it directly.

• Create a customer in CRM. Does it appear, without action, in quotations, invoices and any industry module?
• Enable a module you have not used. Does it need an import or a mapping of your customers and items?

A good answer: modules read the same records, and enabling one is a setting.

1.2 Dependencies stated

Modules depend on each other. Accounting needs Finance. Payroll-based billing needs HR. A vendor should have a clear list and block a bad combination at setup.

1.3 One transaction

Ask whether a document and the entries it produces commit together. If a bill can save but its ledger entry fail, you will spend months finding the difference.

Part 2. Rollout

2.1 Time to first real month

For a business of this size, a first real month-end inside a quarter is a reasonable target. Ask what a typical customer did in the first 90 days, not what the brochure says.

2.2 Order of adoption

A sensible order for most businesses:

1. Customers, items, suppliers and opening stock.
2. Sales and procurement, so documents start flowing.
3. Finance and invoicing in parallel with the old process for one cycle.
4. Accounting, with a go-live date and an opening journal (guide).
5. Industry modules and payroll, once the core numbers are trusted.

2.3 Getting your data in

Ask which records can be imported, in what format, and who corrects errors. Opening balances and stock are the difficult ones.

Part 3. Money, tax and language

If you operate in more than one currency or country, check each of these.

See the currency and tax setup guide.

Part 4. Controls and security

• Permissions per module with separate rights to view, create, edit, delete and approve.
• Approvals where money leaves: purchase requests, large discounts, payroll, returns at a till.
• Audit trail on documents: who created, received, issued or paid, and when.
• Immutability of issued invoices and posted journals. Corrections should be new documents.
• Tenant isolation enforced in the database, not just in application code.
• Sensitive data: who can see salaries, how bank details are stored.

Ask to see the role list and what each role can do, not just that roles exist.

Part 5. Fit for your industry

Industry modules are where vendors are weakest, and where the limits matter most. For each one you need, ask:

• What is the workflow from the first document to the last?
• What does the module not do? Ask for specifics.
• Which of those missing things would you have to run outside the system?

A vendor with a specific list of limits has looked at them. Examples of the kind of answer you want: "receipts are sales receipts, not tax invoices", "no bank reconciliation", "no customer portal".

Part 6. Cost

Per-seat pricing is easy to compare and often wrong for how you work. Ask:

• What is included at each price, and what is a separate charge?
• How does price change when you add a module, a company or a user?
• Is anything priced that you cannot use today?
• What does it cost to leave: export format, retention of your data?

Part 7. Scorecard