Articles · ERP

2026-11-12 12 min EN / FR

Odoo or custom software? How to decide

"Should we take an ERP or have something built?" is one of the most expensive questions a small company asks, and it is often answered by whoever pitched last. A better approach is to look at your processes first and the tools second.

The core idea

An ERP is a bet that your business looks like most businesses. You adopt its logic in exchange for not having to build it. Custom software is the opposite bet: your business is specific enough that fitting it into someone else's logic costs more than building your own.

Most companies sit in between, which is why the answer is usually a standard ERP plus a few targeted custom pieces, not one extreme.

Step 1: Describe your processes in plain words

Before looking at any product, write down how work flows from first contact to payment:

  • How does an order or request arrive?
  • Who validates it, and what do they check?
  • How is stock, time or capacity reserved?
  • How do you invoice, and on what basis?
  • What do you need to report on each month?

Mark each step as standard (every company in your sector does it this way) or specific (it is how you win, or it is forced on you by a client or regulation).

Step 2: Read the result

  • Mostly standard, a few specifics: ERP, with a few custom modules or integrations.
  • Mostly standard, one big specific: ERP for the standard part, plus a separate custom application connected through an API for the specific part.
  • Mostly specific: custom software, or an open source base you adapt heavily.
  • Small and simple, few people: neither. A good accounting tool and some well-chosen automation may be enough.

Cases

A shop or distributor with stock

Products, variants, purchasing, stock levels, shipping, invoicing, and possibly an online shop. This is the classic ERP use case, and a standard ERP covers most of it. The value is having stock, sales, purchasing and accounting in one place, so nobody re-enters data. Custom software rarely makes sense here, except for unusual pricing rules or integrations with a specific logistics partner.

A service company (consulting, agency, installation)

Quotes, projects, timesheets, invoicing based on time or milestones, and sometimes subscriptions. An ERP handles this reasonably well if your invoicing logic is conventional. If you bill using complex rules (tiered rates, shared budgets between clients, usage-based formulas), check those rules early, because that is where standard tools start to bend.

A small manufacturer

Bills of materials, work orders, production planning, stock of components and finished goods. Standard ERP manufacturing modules can cover a lot, but this is where a workshop with your real process matters most. The risk is not the software, it is modelling your shop floor accurately and getting people to record data consistently.

A business with an unusual core process

Examples: a booking logic tied to physical resources, regulated workflows, pricing driven by technical configuration. If this process is your competitive advantage, it deserves software built around it. Connect it to a standard back office for invoicing and accounting rather than rebuilding those.

A team that outgrew spreadsheets and no-code tools

A tool that started as a simple table and now runs the business. Often the right move is not a full ERP but a small custom application with a proper database, which reproduces what already works and removes what does not. Compare the cost of that against an ERP that will force you to change your habits.

Stuck between ERP and custom?

We can map your processes with you and propose a scope that stays ownable: Odoo, a custom piece, or a mix.

Describe your case Custom solutions

Questions that settle most debates

  • How many of our processes are genuinely different from our competitors'? If the honest answer is "one or two", you want an ERP.
  • Who will own the system internally? Both options fail without a named person.
  • How often do our processes change? Frequent changes favor a configurable platform. A stable, specific process favors custom.
  • What must integrate with it? Shop, marketplace, payment provider, logistics, accountant, existing tools. Check each integration before choosing.
  • What happens in five years? Consider upgrades, maintenance, key-person risk, and your ability to change provider. Put that in an exit plan.
  • What are we ready to change in our organisation? An ERP asks you to adapt. If you cannot, custom is more honest.

What you give up with each choice

ERP (standard platform)

  • Faster start, mature accounting, stock and reporting
  • You inherit the platform's logic, and its upgrade cycle
  • Heavy customisation makes upgrades harder and costlier
  • Licensing or support costs may grow with users or modules

Custom software

  • A fit to your process, and full control of the logic
  • You carry the full build and maintenance cost
  • You must handle everything: accounting rules, reports, permissions, backups (see backups that actually restore)
  • Documentation and code ownership become critical

Open source ERP adapted by a provider

A middle path. The base is shared and inspectable, you can host it yourself or under accounts you own, and customisation is possible. The condition is that customisations are written cleanly, kept limited, and documented. Odoo is often in this category when you keep Community or a controlled Enterprise setup under your accounts.

Rules of thumb

  • Configure before you customise. Every custom module is something to maintain and migrate at each upgrade.
  • Customise to remove work, not to copy the past. "That is how we have always done it" is a poor reason for a custom development.
  • Keep the accounting standard. Local tax and accounting rules are the worst place to be creative.
  • Start with a small scope, then extend. Companies that try to cover everything on day one rarely finish.
  • Insist on ownership: your hosting account, your database, your code repositories, your keys. The 30-minute account audit is a useful checklist before you sign.

When you probably need neither

  • You have fewer than a handful of users and simple invoicing
  • Your pain is one specific task, not the whole workflow
  • Nobody has time to own and maintain a system

In these cases, a good accounting tool, a few integrations and a couple of automations will serve you better and cost less.

A simple decision flow

  1. Are your processes mostly standard? Yes: go to 2. No: go to 4.
  2. Do you have someone who can own the system? Yes: go to 3. No: fix that first.
  3. Choose an ERP, with minimal customisation and a limited first scope.
  4. Is the specific process your competitive advantage? Yes: build custom for that process and connect it to a standard back office. No: try to simplify the process until an ERP fits.

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