Should you adopt an off-the-shelf product available online by subscription (SaaS), or have custom software built? The question comes up for a CRM, a job-management tool, an HR system, a customer portal or a scheduling tool. Both options have merit. The right choice depends less on technology than on how central the process is to your business. Here is a practical way to decide.
Two models, two logics
SaaS software is designed for thousands of companies. It covers the most common needs of a trade, evolves according to its publisher’s roadmap and is paid for by subscription, usually per user. You adopt it as it is, within its settings.
Custom software is designed for your organisation. It mirrors your processes, rules and vocabulary, and integrates with your other tools. You own it; it evolves according to your priorities. The upfront investment is higher, but there is no per-user fee set by a publisher.
The comparison
| Criterion | SaaS | Custom software |
|---|---|---|
| Time to get started | Fast | A few weeks to a few months |
| Upfront cost | Low | Higher |
| Recurring cost | Subscription, often per user | Hosting and maintenance |
| Fit with your processes | Limited to configuration | Complete |
| Integration with other tools | Depends on available connectors | Designed around your tools |
| Evolution | Up to the publisher | Up to you |
| Ownership and data | With the publisher, export varies | Yours |
| Main risk | Dependence on the publisher | Quality of development and maintenance |
When to choose an off-the-shelf product
SaaS is almost always the right call when:
- the process is standard and does not set you apart (general accounting, payroll, email, office tools);
- a well-established product covers most of your needs without contortions;
- the number of users stays modest, keeping subscription costs in check;
- you need a tool right away.
In those cases, building an equivalent would be reinventing the wheel. Better to invest in configuring the tool properly and connecting it to the rest of your systems.
When to choose custom software
Custom software is justified when:
- the process is at the heart of your value: the way you produce, serve customers or plan is what makes you different;
- off-the-shelf products force you to work around the tool: side spreadsheets, re-keying, manual steps;
- you need to connect several tools that don’t talk to each other and move data without re-entering it;
- a SaaS product’s per-user cost becomes disproportionate as the team grows;
- your confidentiality or hosting requirements are incompatible with a shared service;
- you want to build AI into your processes in ways standard software rarely allows.
The third way: hybrid
In practice, the best answer is often hybrid: keep off-the-shelf products for standard functions, build what makes you distinctive, and connect it all.
- A custom customer portal drawing on your off-the-shelf management system.
- A field mobile app feeding your existing ERP.
- A management dashboard consolidating data from several SaaS tools in one place.
- An AI layer that works with your existing software through its APIs or the Model Context Protocol, without replacing it.
This approach limits investment to the part that creates value and leaves publishers to do what they do well.
Comparing over time: total cost of ownership
Comparing a monthly subscription with a development quote makes little sense. The meaningful comparison is the total cost of ownership over three to five years, which adds up:
- for SaaS: subscriptions (multiplied by the number of users and its growth), paid options and modules, initial configuration, connectors, and the time spent working around what the tool cannot do;
- for custom software: initial development, hosting, maintenance and enhancements, and staff training time.
On top of that, in both cases, comes the time gained or lost by users every day. It is often the biggest item and the most overlooked: a few minutes lost per person per day, across a whole team and several years, outweighs the gap between two quotes.
Finally, factor in the exit cost: retrieving your data and switching tools has a price, and it is high when a publisher only offers partial exports.
Questions to ask before deciding
- Does this process set us apart from competitors? If not, an off-the-shelf tool will probably do.
- How much time do we lose working around our current tools? Re-keying, spreadsheets, errors: the hidden cost of the status quo.
- What will the subscription cost in three or five years, with team growth and price increases?
- Can we easily get our data back if we switch? In what format?
- Who will maintain the custom software, and on what terms?
- Which integrations are essential: accounting, banking, email, website?
Signs that it is time to switch
Some warning signs suggest an off-the-shelf tool has reached its limits: the team keeps a parallel spreadsheet “because the software can’t do it”; the same information is typed into two or three systems; reports are rebuilt by hand every month; new staff need weeks to learn the workarounds; or the subscription keeps rising while use stays the same. None of these alone justifies a rewrite, but together they usually mean a custom component — or a well-designed integration — would pay for itself.
What makes a custom project succeed
Successful custom software is not software that does everything. It is software that does well what matters, and can evolve.
- Start small: a first version focused on the most costly process, put into service quickly, then expanded.
- Involve users from the mock-up stage: they are the ones who will bring the tool to life.
- Insist on clean, documented code, on standard technologies, so you are not tied to a single supplier.
- Plan for maintenance: security updates, enhancements, backups, monitoring.
- Keep ownership of the code and data, in the contract.
These are the principles we apply to every piece of custom software and every web application we build.
One last piece of advice: whichever option you choose, keep control of your data. Regular exports in an open format, documented business rules, an inventory of integrations — these are what will leave you free to change tools tomorrow.
Frequently asked questions
Is custom software always more expensive?
More expensive up front, yes. Over several years, the comparison depends on the number of users, the time saved and the cost of current workarounds. An honest calculation includes all three.
Can you move from SaaS to custom software gradually?
Yes: you often start by building add-ons connected to the SaaS (a portal, a mobile app, automations) before deciding whether to go further.
What happens if the developer disappears?
That is the main risk of custom software, and it can be managed: code ownership in the contract, source code held by you, documentation, standard technologies. Another developer must be able to take over the project.
Does AI change the equation?
Yes, in two ways: it speeds up custom development, and it lets you get more out of existing software by driving it intelligently rather than replacing it.
Step By Step, a software and AI studio based in Ajaccio, Corsica, helps you decide and builds the part that really matters. Let’s talk about your project.