What does it cost to modernise a legacy system?

Because nobody can price a system they haven't looked inside. Two order-processing systems can look identical from the outside, and one can take several times the work of the other to modernise, depending on what's in the code and the data. A developer who gives you a range from a phone call has priced what they imagine your system to be, and the difference between that and what it is arrives later as a variation order.

So we price the other way round. A few days inside the system first, then a fixed price for each option. An overrun is then our risk, not yours.

In roughly the order they matter:

• How many processes the system runs. Orders, quotes, invoicing, stock, scheduling, reporting. Each is a stage, and each stage has a price. A system that does three things costs less than one that does fifteen, however old either is.
• The state of the data. Clean, constrained data moves quickly. Data with duplicates, free-text fields that mean four things, and twenty years of half-finished migrations takes longer to move and reconcile, and the reconciliation is where the time goes.
• What it connects to. Sage, Xero, a warehouse system, a customer portal, a scheduled export someone relies on. Every integration has to be understood and either kept working or replaced.
• Whether the source code exists. With source, the rules can be read. Without it, they have to be rediscovered from behaviour and data, which is slower.
• How many people use it, and how. Six users at desks is one problem. Sixty users, some on phones, some customers, is another.
• Regulation. Audit trails, retention, access controls. Legal, financial and healthcare systems carry more of this, and it has to be designed in from the start.
• Where it needs to run. Staying on your server, moving to the cloud, or both for a while.

What doesn't drive it much: the age of the technology. A well-structured VB6 system can be cheaper to modernise than a badly structured one from 2021.

The hard part is already paid for. Working out what a system needs to do is the most expensive part of any software project, and your current system has already done it. It's a living specification. Your team knows what they'd change. Your data comes with you.

Stages help too. Modernising one process at a time means the first price is for one process, and the business gets something working before committing to the next. And small systems are often the quickest wins: an Access database with six users can be the first project.

1. A free consultation. An hour on the system. From it we size the assessment and give you an exact price for that.
2. The assessment. From £395 + VAT, payable in advance. A few days inside the system, then a written report.
3. The report. Each option, stabilise and extend, modernise in stages, or replace, with a fixed price and a recommended first stage. Real numbers, days after we start.
4. Each stage. Priced before you commit to it. 40% on signature, 40% at the first working version, 20% on handover.

The report is yours. Take it to us, another developer, or nobody.

Everything with a defined scope has a price on the site:

• The assessment, from £395 + VAT, sized on the consultation.
• The care plan, 18% of a stage's build cost a year, covering support, hosting, small changes and priority access, monthly by direct debit, 30 days' notice to cancel.
• Work outside an agreed scope, £850 a day, quoted before you commit.
• Included in every build: 30 days of fixes after launch, data migration, full source code and ownership on final payment, handover documentation.

The full terms are on the pricing page.

Three things to look for. A day rate with no fixed scope, which means the risk of an overrun sits with you. A price that was given before anyone looked inside the system, which means it's a guess. And a "phase two" that holds everything you asked for, which means the phase one price isn't the price.

None of those makes a supplier dishonest. They make the number provisional.

Understand first, then price. Marc Allington leads every assessment, and the price in the report is the one you pay. Everything we build runs on open, widely used technology, in your own accounts, with full source code and ownership transferring to you on final payment, so what you pay for is yours.