Custom ERP vs Odoo vs ERPNext: An Honest Guide to Build or Buy

I build custom ERPs for a living, so you'd expect this article to end with "build custom". Often it doesn't.

Odoo and ERPNext are good software. Thousands of businesses run on them happily, and for many companies they're the right answer: live sooner, cheaper to start, and maintained by someone else. The trust hospital behind our EHMS looked seriously at SAP and Odoo before choosing us, and they were right to.

So here is how I'd decide if I were in your seat, including the cases where I'd tell you not to hire us.

The three options in one paragraph each

Odoo is a modular business suite: accounting, inventory, sales, manufacturing, HR and dozens more apps that share one database. There's a free open-source Community edition and a paid Enterprise edition priced per user, with hosting from Odoo or a partner. Customisation ranges from point-and-click (Studio, on Enterprise) to custom Python modules, usually written by an implementation partner.

ERPNext is an open-source ERP built on the Frappe framework, strong in accounting, inventory and manufacturing. The software is free; you pay for hosting, either Frappe's own cloud or a server you run, and for whoever implements and customises it.

A custom ERP is built for your business from the data model up. You pay for the build and for support, but no per-user licences, and every screen exists because someone in your business needed it. For the systems we build, that's typically $15,000 to $56,000 over 7 to 14 weeks. I've broken that down in what a custom ERP costs.

Where off-the-shelf wins

Be honest with yourself about these, because they're common.

• Your processes are standard. You buy, stock, sell and invoice the way most businesses in your industry do. That's precisely what Odoo and ERPNext were designed around.
• You need it running next month. Standard modules can be configured and live in days or weeks.
• You want a large ecosystem. Apps, integrations, partners and other users to ask, in most countries.
• Your budget is small and your team is small. A few users on standard modules is where packaged ERPs are cheapest.
• You don't want to own software. Upgrades, hosting and security are someone else's job.

If most of those describe you, buy. Spend the money you saved on a good implementation partner and on training, which is where packaged ERP projects usually succeed or fail.

Where custom wins

Custom earns its cost in a different set of situations.

Your money-making rules don't fit

Every business has a few rules that make it different, and they're usually the rules that touch money.

At the trust hospital, zakat, sadqa, trust and charity-box funds each had to sit on its own ledger, so a zakat discount could never draw from sadqa. In Turner 10, our real estate ERP, one plot sale can involve a freelancer, a sales officer and an investor's agent, each paid differently, so the system has five kinds of agent. In Ophir, every piece of jewellery carries its weight and karat from purchase to a sale at that day's gold rate.

You can build any of those into Odoo or ERPNext with custom modules. The question is whether you'd end up with a packaged ERP plus a large custom layer, paying for both, and owning the hardest part anyway.

Per-user fees meet a growing team

Licence costs that look small for ten users look different for two hundred across several branches. A custom system has no per-user fee. Do the maths for your own numbers: users × monthly per-user price × 36 months, plus partner fees, against a custom build plus three years of support.

Customisations and upgrades collide

This is the cost people discover in year two. Packaged ERPs release new major versions regularly, and heavy custom modules often have to be reworked to move to them. Skip upgrades and you drift away from security fixes and new features; keep up and you pay for the rework each time. The more you customise, the bigger that bill. A custom ERP has upgrades too, but they're your upgrades, on your schedule, made by people who know the code.

Your people need it in their language

Odoo and ERPNext support many languages, including right-to-left ones. Translation of standard screens is the easy part. A custom ERP lets you design the daily screens for the people who use them: Turner 10 and EHMS run in English, Urdu and Arabic, with layouts, fonts and printed documents designed for right-to-left rather than mirrored.

Support from the people who built it

When the trust hospital chose us, part of the reason was simple: nobody from a global ERP partner was going to drive to Chishtian. I went there, stood at the counters, sat with the accounts staff, and learned how trustee funds were handled before writing a screen. On go-live we moved the running data and the staff across in person, and the hospital didn't close for a day.

The middle path most people miss

It doesn't have to be all or nothing.

• Packaged core, custom edge. Run accounting in Odoo or ERPNext, and build a small custom app for the one workflow that doesn't fit, connected through their APIs.
• A ready product for your industry. Industry-specific software, built once and reused, often fits better than a generic ERP and costs far less than a custom one. That's what our own EHMS hospital software and X3 retail ERP are for.
• Custom later. Start on a packaged ERP, learn where it hurts, and build custom only for those parts once you know exactly what they are.

A 10-question scorecard

Answer each with yes or no.

1. Do your core money rules (funds, commissions, pricing, units of stock) match the standard way your industry works?
2. Could you live with the standard screens for most daily work?
3. Do you need to be live within a month?
4. Will your user count stay small (say, under 25) for the next three years?
5. Do you want someone else to handle upgrades and hosting?
6. Is there a strong implementation partner near you?
7. Are your integrations mostly with popular tools that already have connectors?
8. Is your budget for the first year under the cost of a custom build?
9. Are you comfortable adapting some processes to the software?
10. Would losing a feature in an upgrade be an inconvenience rather than a crisis?

Mostly yes: buy Odoo or ERPNext. Mostly no: a custom ERP is likely worth it. Split down the middle: look at the middle path, a packaged core with a small custom app, or an industry product.

What we'll tell you on a call

If your answers point to Odoo or ERPNext, we'll say so in the written plan. We'd rather lose a project than build an expensive system you didn't need, and the plan is yours to keep either way. If they point to custom, we'll show you what the first version would include, what it costs and how long it takes, using the same estimator as every price on our custom ERP development page.

If you run a housing scheme or sell plots on installments, our Odoo vs real estate ERP comparison covers that case in detail. To put numbers on the build side, use the real estate ERP, retail ERP and POS and hospital management system estimators. If you would rather start from a ready product, X3 is the retail ERP we built ourselves, one of our ready-made products, with packages from PKR 350,000.

Common questions

Is a custom ERP better than Odoo? Not in general. Odoo is better for businesses with standard processes that want to be live quickly. A custom ERP is better when your core rules don't fit, when per-user fees will grow large, or when heavy customisation would make upgrades expensive.

Is ERPNext really free? The software is open source and free to use. You still pay for hosting, implementation, customisation and support, which are where most of the cost of any ERP lies.

How much does it cost to customise Odoo? It depends on how far your processes are from the standard modules. Small changes can be configuration; large ones become custom modules that also need maintaining through upgrades. Get a partner's estimate for both the build and the upgrade cost.

Can a custom ERP work alongside Odoo or ERPNext? Yes. A common pattern is to keep accounting in the packaged ERP and build a custom application for the workflow it can't handle, connected through APIs.

How long does a custom ERP take compared with Odoo? Standard Odoo or ERPNext modules can be live in days to weeks. The custom systems we build take 7 to 14 weeks, with a working demo every week.

Not sure which side you're on? Get a free project plan. We'll tell you honestly whether to build, customise or buy.