Still running on the old system?Let's plan its last day.
It still runs the business, so replacing it always looked like a project too big to start. We move it across one part at a time while your business keeps working on it, with your own team alongside ours, so it can keep up with whatever the business wants next, AI included.
- 100+
- products shipped
- 3 in 100
- applicants make the team
- 3×
- voted SA’s best software development company (MyBroadband, 2024–2026)
- Lesaka
- Tiger Wheel & Tyre
- Romans Pizza
- City Lodge
- Absa
- Old Mutual
- DP World
- Peermont
- Hyundai
- Nestlé
The legacy way was always too big to start
The system works, so it stays. Every change takes longer than it should, fewer people know how it works, and anything new has to be built around it. Replacing it the old way meant a long project before anyone saw a result, so it kept moving down the list.
“If we try and do it the old legacy way, it would have taken us 12 to 14 months.”
“Software that just works for the business. I feel for the people that work here.”
Your team keeps it running every day. What's been missing is a way to replace it that doesn't put the business on hold.
The slowest part of modernising has changed
The slow, risky part of modernising was always understanding the old system: years of code, and business rules nobody wrote down. That's where AI has changed the work most, and where we lead with it.
"It was not possible five years ago." (an IT leader, on what has changed)
- 01
Mapping what you have. AI agents read the old code and list every screen, rule and integration they find. An experienced engineer confirms each one before anything moves.
- 02
Building the new part. AI does the groundwork. Our engineers design every part and review every line before it ships.
- 03
Proving it behaves the same. Automated tests check each new part against what the old one did, before your people switch over to it.
Nothing reaches your business until one of our engineers has signed it off.
Keep, modernise or rebuild, decided part by part
We start by finding out exactly what you have, and give your leadership the evidence to decide. Most systems need a different answer for different parts, and sometimes the honest answer is to keep what works and build what's required.
- 01
Keep and improve. The foundations are sound and the trouble sits in a few places. We fix those and leave the rest running.
- 02
Modernise step by step. It runs the business and can't stop, but parts of it hold everything back. We replace those parts in turn.
- 03
Rebuild. Its technology has run out of road, and patching only delays the cost. We plan the new system around the rules the old one taught you.
Your business keeps running while each part moves across
The legacy way waited for one big switch-over. Here the new system grows around the old: the two run side by side, and each part switches over when it's ready and proven.
- 01
One part at a time. Your people move to each new part as it's ready, and the old one keeps covering everything else.
- 02
Your data and rules come with you. Years of data and the business rules nobody wrote down move across intact.
- 03
The safety net goes in first. Proper releases come before the first part moves, so every part after it moves faster and more safely.
- 04
Your team alongside ours. Your developers know the old system better than anyone. They work with ours throughout and own the new one with us.
How we work with your team →
Every part that moves across brings the old system's last day closer.
The route that fit each system
- 01
Modernise step by step · Jumpstart. A customer engagement platform in service since 2013, rebuilt screen by screen while campaigns kept going out every day. Rework stayed at 1%.
Read the Jumpstart story → - 02
Rebuild · Romans Pizza. The business had outgrown its ordering platform, so we started again on one foundation for app, web and call centre. It was live in a few months.
Read the Romans story → - 03
Rebuild · InsideData. Our independent code audit gave their leadership the evidence to decide on a rebuild. We then worked with them to plan what the new platform must do.
Who is Codehesion?
Codehesion is a software development company of 65+ engineers, designers and analysts, founded in 2017 and based in Centurion, Gauteng. We build, rescue and modernise software for companies like Lesaka, Tiger Wheel & Tyre, Romans Pizza and City Lodge. MyBroadband readers have voted us South Africa's best software development company three years running.
Not quite your situation?
What people ask us first.
Will the business keep running while you modernise?
Yes. Old and new run side by side, and each part switches over only when it's ready and tested.
Will we lose data, or the rules nobody wrote down?
No. We map every rule and integration before anything moves, and your data comes across intact.
Can our own developers stay involved?
We'd like them to. They know the system best, and they work alongside ours from the first part to the last.
Our system is very old. Is that a problem?
No. However old the technology, we start by finding out exactly what it does.
Where do we start?
Usually with a code audit, so you decide with evidence. If you already know what the new system must do, we can start with a Discovery week instead. → `/services/discovery/`
Can we do it in phases?
Yes, that's how we prefer to work. Each part goes live on its own, so you see progress early and can plan the budget part by part.
Will the new system work with AI and modern tools?
Yes. It's built to connect, so what the business wants next can plug straight in.
What does it cost?
It depends on what you have and which route fits each part. We'll give you a clear price after the first conversation.
One morning the old system is switched off, and nobody misses it. Your people are already working faster on the new one.
Let's set a date for its last day.
Tell us what's holding you back.