Odoo with custom work or six tools side by side: what does it really cost?
Odoo's licences are rarely cheaper than those of your separate tools. The difference lies in everything you don't see on an invoice today.
Short answer. On licences alone, Odoo usually doesn't win. The difference is in integrations, double work, administration and the missing overview. In our worked example that adds up to €250,000 a year. If your landscape sits at the low end, the overview is the only reason to switch. And we'll say so.
A situation we come across often: an installation company that installs and repairs across the country. About 150 vans, 350 technicians, its own logistics. The company is growing fast and acquired a few companies along the way, each with its own tools. The ERP has been running for fifteen years. Around it, in the parent company alone, sit six applications. The question is simple: what does it cost to keep it this way, and what does it cost to bring everything into one system?
How it piles up
Nobody chooses six tools on purpose. The ERP doesn't do what after-sales service needs, so ticketing comes along. Planning 350 technicians doesn't fit in the ERP, so a planning tool with an app comes along. An acquired company brings its own accounting. Maintenance contracts stay on paper. And because nobody can see in one screen how the company performs, a dashboard tool is added. That's tool number seven, not a solution.
What you see: the licence invoices
For a company this size, the visible invoices quickly add up to €190,000 – €315,000 a year. A worked example with common market prices, not a quote: replace the assumptions with your own numbers.
| Item | Assumption | Per year (excl. VAT) |
|---|---|---|
| Planning and technician app | 350 users × €25–40 a month | €105,000 – €168,000 |
| Fifteen-year-old ERP | maintenance contract and hosting | €40,000 – €60,000 |
| After-sales ticketing | 30 users × €50–90 a month | €18,000 – €32,000 |
| Tools of acquired companies | own accounting and planning | €20,000 – €40,000 |
| Dashboard tool | 20 to 40 readers | €5,000 – €15,000 |
| Contract management | paper and Excel | €0 |
| Total | €188,000 – €315,000 |
That €0 for contract management is the most expensive line in the table.
What you don't see: four hidden costs
In this example the hidden costs run between €85,000 and €250,000 a year. They're on no invoice, because they sit in wages and in missed revenue.
Integrations. Six tools that have to talk to each other need integrations, and every update can break one. Count on a middleware subscription and 20 to 40 development days a year: €20,000 to €55,000.
Double work. An intervention is planned in the planning tool, closed in the app, retyped in the ERP and checked in Excel. Spread across planners, accounting and after-sales, that's quickly half to two full-time people: €30,000 to €120,000.
Administration and security. Six systems means creating and closing accounts six times for every new or departing employee, and six vendors in your security review. Half to one full-time person in IT: €35,000 to €75,000.
The missing overview. The biggest cost and the hardest to measure. Contracts on paper don't get indexed. Interventions under contract get invoiced anyway, or don't. An acquisition is never really integrated, because nobody can put the numbers of both companies side by side.
What Odoo with custom work honestly costs
In this example about €240,000 to €250,000 a year in licences and hosting. That's in the same range as the licences of the six tools together, and we'd rather say so straight away.
Licences. For custom work, multiple legal entities in one database and external integrations you need the Custom plan: at the time of writing €44.90 per user per month billed yearly (€35.90 with the current promotion). For 430 users that's about €232,000 a year. Odoo 20 also has a €7.90 light licence, among other things for self-service and barcode scanners. Check who really qualifies: whoever works fully in the software counts as a full user.
Hosting. On Odoo.sh or on your own network: count on €10,000 to €20,000 a year at this size.
Maintaining custom work. Building a module is easy today. Maintaining it through every new version is the real work. With us, that's part of the subscription. If you work with another partner, ask who tests and repairs the custom work after an upgrade, and what that costs.
Implementation. That comes on top, once or spread out, and has to be earned back by the difference in yearly costs. So it isn't in the yearly comparison below, but it is in your decision.
Side by side
At the low end both routes cost about the same per year. At the high end Odoo with custom work is up to €250,000 a year cheaper. That difference comes almost entirely from the hidden costs, not from the licences.
| Cost per year | Six tools side by side | Odoo with custom work |
|---|---|---|
| Licences | €188,000 – €315,000 | €232,000 |
| Hosting | in licences and ERP contract | €10,000 – €20,000 |
| Integrations | €20,000 – €55,000 | €0 – €10,000 |
| Double work | €30,000 – €120,000 | €0 – €20,000 |
| Administration and security | €35,000 – €75,000 | €15,000 – €25,000 |
| Total | €273,000 – €565,000 | €257,000 – €307,000 |
Two honest caveats. If your landscape sits at the low end of the range, Odoo isn't cheaper and the overview is the only reason to switch. And the fourth hidden cost, the missing overview, isn't in this table. In practice it's often the biggest.
From practice: and then come the smart little apps
What we see in practice is that another layer comes on top of the six tools. At an installation company with a few hundred vans, three AI proposals were on the table to close the gaps between the systems: a planning agent working between the ERP, the calendar app, an Excel file and the mailbox, a control app that checks manual time registrations against track-and-trace and fuel card data, and a chatbot for customer questions. Together about €65,600 to implement and €52,500 a year, for one company in the group, with nine integrations to seven systems. The licences of those seven systems simply keep running.
Each of those apps is defensible. But they make the fragmented landscape more expensive to leave, not cheaper to keep. Read: baling wire between the applications →
Not everything has to go
A separate tool is sometimes the better choice, such as very deep warehouse management or complex finite scheduling. Then we integrate that one tool well, instead of six tools badly. The test: does this tool do something Odoo can't, and does your team like using it? Two yeses, and it stays.
Integrate acquisitions per domain, not per company. First the accounting in the same database, as a separate legal entity. Then planning and after-sales service. That way, after the first phase, you already see the numbers of the whole group side by side.
Do the sums yourself
Odoo prices for Belgium checked on 18 October 2026 via oec.sh; Odoo adjusts its prices regularly, so always check the current price. The amounts from practice come from real, anonymised proposals (excl. VAT, rounded). All other amounts are indicative market prices for a worked example, not a quote.
If the answer to the last question is days rather than minutes, you know where the real cost lies.
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