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Legacy application modernization services

Legacy application modernization services

Senior LATAM engineers who rebuild the systems your business runs on while your business keeps running on them, at 30-50% below US rates.

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Applebees
KPMG
Mastercard
Microsoft
NetJets
Toyota
  • 15+
    years delivering software
  • 100+
    senior engineers across LATAM
  • 6-8h
    daily overlap with US teams
  • 6+
    Fortune 500 & global brands trust us
Who we are

Senior engineers who modernize systems that cannot stop running

The applications worth modernizing are the ones the company depends on daily, which is exactly why the project keeps getting postponed.

FusionHit is an application modernization company with senior engineers across Latin America who work in stages, on your hours, so nothing goes dark while it happens.

Two FusionHit engineers working together in a meeting room \
WHAT WE DELIVER

Application modernization services we deliver

What US teams hand us when the system still works but has stopped keeping up.

Modernization assessment

A structured read of the codebase, the dependencies and the operational risk, delivered as a recommendation per component with the effort and the sequence to do it.

Monolith to microservices

Monoliths split along domain boundaries and moved out one service at a time, with the original system serving traffic until each piece is proven.

Application re-platforming

Applications moved onto supported runtimes, frameworks and databases, which is often the cheapest way to end the security and licensing exposure.

Legacy system integration

An API layer built over systems that cannot be replaced yet, so new products can be developed against them instead of waiting for them.

Data modernization

Schemas, stored procedures and reporting migrated onto modern data platforms, with reconciliation at each step so the numbers keep matching.

UI modernization

Aging front ends rebuilt in a current framework, screen by screen, so users get a modern interface before the back end finishes changing.

STRATEGY

Rehost, replatform, refactor or rebuild, and how to tell which

Every provider lists these four. Almost nobody tells you how to choose, so here is the honest comparison. Most estates need more than one of these. The assessment decides per component rather than for the whole system, because applying a single strategy across everything is how modernization budgets disappear.

Rehost
Replatform
Refactor
Rebuild
What changes

Where it runs

Where it runs and on what

How it is built inside

The application itself

Effort

Lowest

Low

High

Highest

Disruption risk

Lowest

Low

Managed, stage by stage

Highest

Ongoing cost impact

Little or none

Some

Substantial

Substantial

Choose it when

Hardware is end of life or a datacenter exit has a date

The application is healthy but the runtime is unsupported

The code works and still cannot scale or change fast enough

The business model moved and the old design cannot express it

What changes

Rehost

Where it runs

Replatform

Where it runs and on what

Refactor

How it is built inside

Rebuild

The application itself

Effort

Rehost

Lowest

Replatform

Low

Refactor

High

Rebuild

Highest

Disruption risk

Rehost

Lowest

Replatform

Low

Refactor

Managed, stage by stage

Rebuild

Highest

Ongoing cost impact

Rehost

Little or none

Replatform

Some

Refactor

Substantial

Rebuild

Substantial

Choose it when

Rehost

Hardware is end of life or a datacenter exit has a date

Replatform

The application is healthy but the runtime is unsupported

Refactor

The code works and still cannot scale or change fast enough

Rebuild

The business model moved and the old design cannot express it

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Why FusionHit

Why US companies choose FusionHit for modernization work

  • Senior engineering talent

    Vetted nearshore engineers with production experience across industries and modern stacks.

  • Real-time collaboration

    Nearshore teams aligned with US time zones for synchronous planning, reviews, and delivery.

  • Flexible engagement

    Scale engineering capacity up or down as your roadmap and priorities evolve.

  • Integrated partnership

    We work as an extension of your engineering and product teams, not as a detached external vendor.

FusionHit senior nearshore engineers working with a US client team
CASE STUDIES

Systems we modernized while they stayed in service

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Your system can get there too, without a weekend outage.

Talk to an expert, 30 minutes, no commitment.

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INDUSTRIES

Modernization under the constraints of your sector

What makes a system hard to replace is rarely the code. It is what depends on it.

Fintech

Core systems modernized with the reconciliation and audit evidence your regulator will ask for afterwards.

Healthcare

Clinical systems updated without interrupting care, and without touching PHI outside a HIPAA-aligned path.

SaaS

Single-tenant products re-architected into multi-tenant platforms, one customer cohort at a time.

Logistics

Operational systems rebuilt around a business that never has a maintenance window.

Retail

Commerce platforms modernized between peak seasons, with a hard freeze before each one.

Manufacturing

Plant systems updated while the line keeps producing, including the integrations to equipment nobody wants to touch.

Explore all industries
TECHNOLOGY EXPERTISE

Legacy stacks we work with, and what we move them to

The question worth asking a modernization partner is not what they build with today, but what they have taken apart.

Legacy we maintain during migration

Modern backend targets

Modern frontend targets

Containers & orchestration

Cloud

Data

HOW WE ENGAGE

Three ways to engage a modernization team

Staff augmentation

Senior engineers added to your existing team, under your direction, in days rather than months.

Dedicated development teams

A team working only on the modernization, sprint after sprint, while your in-house engineers keep the current system running.

Full project outsourcing

You hand over the scope and we deliver it under our management, covering assessment, migration, testing and handover.

Moving the whole estate to the cloud?

Cloud migration services →
OUR PROCESS

How a modernization engagement starts

01

Discovery call

The system, what it costs you today, and what is forcing the decision (30 minutes).

02

Assessment

A component-by-component recommendation with strategy, effort and sequence, delivered as a document you own.

03

Interviews

You meet and approve every engineer.

04

Staged delivery

One component at a time, each proven in production before the next one starts.

FAQ

FAQs about our application modernization services

01

How much does application modernization cost?
Senior nearshore rates run 30-50% below equivalent US salaries and consultancy fees. What drives the total is which strategy each component needs, and that is what the assessment settles. You get a line-item estimate per component, so you can approve the modernization in pieces rather than as one number.
02

What does the assessment include and how long does it take?
We read the codebase, map the dependencies and integrations, review the operational and security exposure, and interview whoever still knows the system. You get back a written recommendation per component with strategy, effort and sequence. It is a paid engagement, it is yours to keep, and you are free to execute it with someone else.
03

Can you modernize a system with no documentation?
Yes, and it is the normal case. Original developers have moved on and the documentation, when it exists, describes a version from years ago. We reconstruct the behaviour from the code and from the data, and write down what we find as we go, which is often the first real documentation the system has had.
04

How do you avoid taking the system down?
By never switching everything at once. Components move one at a time behind a routing layer, the old path stays available until the new one is proven with real traffic, and each step has a way back. Users see the change gradually rather than on a Monday morning.
05

How do we know the new system does the same thing as the old one?
We establish the current behaviour before we change it, with characterization tests written against the legacy system, and run both paths in parallel during cutover to compare outputs. Feature parity gets demonstrated rather than assumed.
06

Should we modernize or replace with an off-the-shelf product?
Sometimes replacing is the right answer, and we will tell you when it is. The test is whether the system encodes something specific to how your business competes. If it does, that logic is the asset and rebuilding it around a package usually costs more than modernizing it.
07

Can we do this while our team keeps shipping features?
Yes, and it is how most of these engagements are structured. Our team takes the modernization workstream and your engineers keep the roadmap moving, with a shared branching strategy so the two do not collide.
08

What happens to our engineers who know the old system?
They become the most valuable people in the project. We work alongside them rather than around them, and the knowledge transfer runs both ways, so your team ends up owning the new system rather than inheriting another black box.
09

Do you keep the legacy stack running during the migration?
Yes. Somebody has to maintain the old system while the new one is built, and our engineers cover both, which avoids the situation where the legacy platform decays because everyone has moved on to the replacement.
10

How fast can engineers start?
We present matched profiles within days, you interview and approve them, and most engineers onboard in under 2 weeks. An assessment can usually start sooner.
11

How much time zone overlap will we have?
Our engineers work across Latin America on US Central and Eastern time, which gives 6-8 hours of daily overlap. In modernization that matters more than in greenfield work, because the answers about why the system does what it does live with your people.

Ready to find out what your system needs?

Tell us what you are running and what is forcing the change, and we will show you the team and the sequence.

Trusted by leading teams

  • Mastercard
  • NetJets
  • KPMG
  • Applebees

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