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Legacy application modernisation

For teams running software that still works but nobody wants to touch. We take on applications we did not build, make them safe to change again, and stay on to run them.

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What this covers

Legacy application modernisation, end to end.

Codebase and infrastructure assessment

We read the code, the database, the deployment setup and whatever documentation survived. You get a written picture of what the system does, where it is fragile, and what it would cost to leave it alone.

Dependency and platform upgrades

Old framework versions, unsupported runtimes, end-of-life databases. We plan the upgrade path, take it in steps that can each be released, and keep the application working the whole way through.

Incremental rebuild

Where a rewrite is warranted, we do it a piece at a time behind the existing interface. Users stay on the old system until each new part is proven, so there is no single switchover day.

Test coverage and CI

Most legacy systems have no tests, which is why nobody dares change them. We add coverage around the parts you change most, then a build pipeline that runs it on every commit.

Data migration and clean-up

Years of a system in production leave duplicate records, orphaned rows and columns nobody can explain. We map what is there, agree what is kept, and move it with a rehearsed, reversible migration.

Integrations and API layer

Legacy systems are usually isolated. We build an API in front of the existing data so newer tools, reporting and AI agents can read and write to it without a rewrite underneath.

How it runs

Plan. Build. Run.

01

30 minute call

You tell us what the system does, what breaks, and what you are trying to change. We tell you whether modernisation is the right call or whether you should replace it outright. No charge for this.

02

Assessment

We get access to the code and the running environment and spend a fixed period reading both. The output is a written report: risks in priority order, the work required, and what each option costs you.

03

Fixed scope and price

You choose a path from the report. We turn it into a scope with a timeline and a fixed price before any build work starts. If the scope changes later, we price the change before doing it.

04

Build, then run

We do the work in releasable steps rather than one long branch. When it is done you can take it in-house, or we move onto the managed retainer and keep running it.

Why infoloop

We do not hand over and leave.

  • We stay on afterwardsOur retainer covers monitoring, fixes with response targets, security updates and a monthly report. Modernised software goes stale again if nobody owns it, so we keep owning it.
  • We work on systems we did not writeReading someone else's code is normal work for us, not a special case. We do not ask for a rewrite because the existing code is unfamiliar.
  • You get an assessment before a quoteNobody can price legacy work honestly from a phone call. We look at the system first, write down what we found, and quote the work against that.
  • Nothing switches over in one nightWe release in steps that can each be reversed, and rehearse data migrations against a copy first. If a step goes wrong you lose one change, not the application.
  • We hand over properly either wayDocumentation, credentials and runbooks are yours from the start. Staying with us should be a decision you make, not one the handover forces on you.

What you get

Every engagement includes these, in writing, before work starts.

  • A written assessment of the codebase, database and hosting, with risks ranked
  • An upgrade or rebuild plan with each step sized, sequenced and independently releasable
  • Automated test coverage over the areas of the system you change most often
  • A build and deploy pipeline that runs tests and can roll a release back
  • A rehearsed data migration with a verified rollback, run against a copy first
  • Runbooks, architecture notes and credentials handed over in your own accounts

Who this is for

Three situations where this is the right call.

The original developer is gone

An agency or a single contractor built it, then moved on. It still runs, but nobody left in the business knows how, and every small change turns into a negotiation about risk. You need someone to take custody of it.

The platform under it is end of life

The framework, runtime or database version you are on no longer receives security patches, or your host has given you a date. The application is fine; the ground under it is not, and the deadline is real.

A rewrite has been quoted and you flinched

Someone has told you the only option is to build it again from scratch. You want a second read on whether that is true, and a costed comparison against upgrading what you already have.

Proof

Software we built, and still run.

We run: the managed retainer

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Machinery ERP, rebuilt and run

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Questions

What buyers ask us first.

Do you modernise the existing system or rebuild it from scratch?
Whichever the assessment supports. Rebuilding is right when the data model itself is wrong, when the platform has no upgrade path left, or when the business rules have moved so far from the original design that you fight the code on every change. Otherwise upgrading in place is cheaper and less risky, because the existing system already encodes years of edge cases nobody wrote down. We read the code before forming a view, put both options in writing with what each costs, and let you choose. We will say when a rebuild is not warranted, even though it is the larger piece of work for us.
What does an engagement cost and how is it structured?
It runs in two parts. First a paid assessment: we take access to the code and the running environment, spend a fixed period on it, and produce a written report with risks in priority order and costed options. That part is deliberately small, and the report is yours whether or not you continue. Second, the build work, quoted as a fixed scope with a fixed price and a timeline once you have chosen an option. We do not bill open-ended hours on the build. If the scope changes mid-project, we price the change and you approve it before we start. The managed retainer afterwards is priced separately, monthly.
Will the application stay running while you work on it?
Yes. We work in steps that can each be released and reversed rather than one long branch that lands months later. Where a piece is being replaced, the new version usually goes in behind the existing interface, so users carry on with the old path until the new one is proven, then we switch that one piece over. There is no single cutover night where everything moves at once. For data migrations we rehearse against a copy of production first, verify the result, and keep a tested rollback ready before we run the real one.
What happens after the work is finished?
You choose. Everything sits in your own accounts and repositories from the start, with runbooks, architecture notes and credentials handed over, so taking it in-house or to another supplier is a clean exit. Or we move onto our managed retainer, which is what most of this work is really for: monitoring, fixes with agreed response targets, security and dependency updates, small improvements, and a report each month covering what changed and what needs attention. Modernised software goes stale again if nobody owns it. The point of the retainer is that somebody does.
How much access do you need, and what about our security?
For the assessment we need read access to the source code and enough visibility of the running environment to see how it is deployed and where the data lives. Read-only is fine at that stage. For build work we need write access to a repository and a non-production environment. We work in your accounts rather than ours, so access can be revoked at any point and nothing depends on us holding it. We do not need production data to work with: a masked or anonymised copy is enough for development and for rehearsing migrations, and we will ask for that first.
What if the system has no tests and no documentation?
That is the normal condition of the systems we are asked to take on, and it is usually the reason nobody dares change them. We do not try to document everything or reach full coverage, because that spends a lot of money on parts of the system nobody touches. Instead we add tests around the areas you change most and the paths where a failure costs you money, so those become safe to work on first. Documentation is written as we go and kept to what someone would actually need to run the thing: how it deploys, what it depends on, and what to do when it breaks.

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Find out what your system actually needs

Thirty minutes on a call, no charge. Tell us what the software does and what breaks. We will tell you whether it is worth modernising, whether it should be replaced, and what an assessment would involve.

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