# Custom software vs SaaS: when to build

> When to buy a SaaS and when to build custom software: three-year costs, flexibility, vendor dependence and a simple way to decide.

URL: https://codegea.com/en/custom-software-vs-saas-when-to-build
Web · 2026-10-08 · Carolina Dávila

Buying a SaaS (subscription software) is almost always the fastest way to solve a problem. Building custom is the way to solve the one no SaaS covers well. The right question is not which is better, but **at what point one option stops being worth it compared to the other**.

> If your process is like everyone else's, buy. If your process is what sets you apart, build. And if you are somewhere in between, start by buying and build what hurts.

## What each one is

- **SaaS:** a ready-made product you use for a monthly or yearly fee. The vendor maintains it.
- **Custom:** a system built for your operation. The code and the data are yours.

## Advantages and limits

|  | SaaS | Custom |
| --- | --- | --- |
| Time to start | Days | Weeks or months |
| Initial cost | Low | Higher |
| Long-term cost | Fees that grow with users or features | Maintenance and evolution |
| Fit to your process | You adapt | It adapts to you |
| Integrations | Those the vendor offers | Those you need |
| Data | In the vendor's system | In your infrastructure |
| Dependence | High (prices, changes, shutdowns) | Low (the code is yours) |

## Signs a SaaS suits you

- The process is standard: basic accounting, email, video calls, generic project management.
- You need to be running now and have no time to build.
- You have no team to maintain software.
- The integrations you need exist and work.

## Signs it is worth building

1. **You pay for several SaaS tools and glue them with spreadsheets.** The real cost is the time of whoever copies data from one place to another.
2. **You adapt your process to the program**, and that adaptation costs you efficiency or quality.
3. **The software is part of your value proposition.** Your differentiator should not live inside someone else's product.
4. **The fee grows with your success.** If they charge per user or volume, the cost shoots up just as you grow.
5. **You need control of your data** for privacy, regulation or deep integration.
6. **Local particularities** the SaaS does not cover well, such as SRI electronic invoicing ([integrated invoicing guide](/en/sri-electronic-invoicing-integrated-with-your-system-or-store)).

## How to compare with numbers

Do not decide on the first month's fee. Do this calculation over **three years** for each option:

- **SaaS:** fee × users × 36 months, plus extra modules, plus the manual work it does not eliminate, plus the cost of migrating if you ever switch.
- **Custom:** initial development, plus hosting, plus maintenance and improvements. To understand how that budget is built, read [how much custom software costs](/en/how-much-does-custom-software-cost-and-how-it-is-quoted).

And add what you do not see: the cost of an error from a manual process, the lost time and the risk of the vendor changing terms or shutting down.

## The middle path

Many companies do not choose "all or nothing":

1. **They start with a SaaS** to validate the process.
2. **They build custom the module that hurts most**, connected to the SaaS through an API.
3. **They replace in stages** whatever makes sense.

It is a low-risk route: you never bet everything on a big development from day one. A clear example is companies that grow with an [off-the-shelf ERP and custom modules around it](/en/custom-erp-vs-off-the-shelf-erp-for-smes-in-ecuador).

## Risks of building (and how to reduce them)

- **Fuzzy scope:** define in writing what goes into the first version.
- **Dependence on whoever builds it:** demand code and documentation in your name.
- **Forgotten maintenance:** budget for support and evolution; a [retainer plan](/en/retainer) covers that.
- **Reinventing the wheel:** do not build what a SaaS solves well (email, payments, chat).

## Our stance

We do not sell custom software to those who do not need it. If a SaaS solves your case, we will tell you. If your process is what makes you different, we build it in stages with deliveries you can test. Learn about our [custom software development](/en/services/custom-software-development) service or tell us your case from [contact](/en/contact).