Legacy application modernization services, phase by phase

Signs your system needs modernization

Legacy software is rarely broken. It still runs the business, which is exactly why it is hard to touch. Legacy system modernization becomes urgent when the cost of leaving it alone starts to show:

• Small changes take weeks because nobody is sure what else they will affect.
• Only a few people understand the code, and they will not be around forever.
• The framework, language version or database no longer receives security patches.
• The system cannot connect to the tools your team and customers now expect.
• It runs on servers that are expensive to keep or hard to replace.
• Users keep spreadsheets on the side because the system cannot do what they need.

Any one of these is a reason to look at the system closely. Several together usually mean that a plan now costs less than a rescue later.

Audit first: what we look at

Every software modernization project starts with an audit, because the right approach depends on what is inside. We review:

• The code: structure, test coverage, dependencies and the parts that change most often.
• The data: its model, quality and volume, and every process that reads or writes it.
• The integrations: each system that sends data in or takes data out.
• The infrastructure: where it runs, how it is deployed and how it is backed up.
• The people: who uses which features, and which features nobody uses any more.

The result is a written report and a roadmap: what to keep, what to rebuild, what to retire, in which order, and what each phase delivers. You can carry it out with us or with your own team.

An audit also tells you when modernization is not worth it yet. If the system is stable, rarely changed and still supported, we will say so, and suggest the few changes that keep it safe in the meantime.

The strangler approach, explained plainly

Replacing an old system in one big switch-over is the riskiest way to modernize: months of work go live on a single day, and anything missed shows up in front of your users. We prefer the strangler approach, named after the strangler fig, a plant that grows around a tree until it can stand on its own.

In practice, we put a thin routing layer in front of the old application that decides where each request goes. We rebuild one area at a time, such as customer accounts, invoicing or reporting, and point the layer at the new version once it is tested. The old system keeps doing everything else. Area by area the new system takes over, until the old one has nothing left to do and can be switched off.

Each phase is small enough to test properly and to roll back if needed, and your users get improvements along the way instead of waiting for one big launch.

Data migration without losing history

The data is usually the most valuable part of a legacy system, and the part that needs the most care. We map every table and field to the new model, clean up duplicates and broken records together with your team, and write migration scripts that run again and again on copies before the real move.

While old and new systems run side by side, we keep the data in sync between them, so users can work in either during the transition. Before each cutover we compare record counts and key totals between the two, and we keep a rollback plan ready until you confirm that everything matches.

We also plan for the data the old system does not hold: documents in shared folders, spreadsheets kept on the side and records that only exist in email. The new system should start complete, not with a second set of side files.

Refactor, rebuild or move to the cloud?

Application modernization is not one technique. Depending on the audit, each part of your system may be:

• Kept as it is, with tests and documentation added around it
• Refactored: the same behavior, cleaner code and supported versions
• Rebuilt on a current stack where the old code cannot be saved
• Moved to AWS, Azure or Google Cloud with our cloud migration and DevOps team
• Replaced by an off-the-shelf product, where one now does the job well

Most projects mix these. When a new system is the better answer, our custom software development team builds it, with the same audit and data migration work behind it.

Along the way we add what old systems usually lack: automated tests, a deployment pipeline and monitoring, so every future change is safer than the ones before it.

How to work with us

Modernization usually starts with the audit as a fixed-scope piece of work, followed by the phases in the roadmap, each with its own written scope. Long programs often suit a dedicated development team that learns the old system once and stays with it. After the final cutover, we can stay on for maintenance, or hand over to your team with documentation and tests in place.

You can also start small. If one part of the system causes most of the pain, the first phase can deal with that part alone, and the rest of the roadmap can wait until you have seen the result.

To start, contact us with a short description of the system, roughly how old it is and what it does for your business.