Choosing the Right Legacy Application Modernization Companies

[Victor Zhadan]

When you start comparing different Legacy Application Modernization Companies, the first thing you notice is how vague and similar their promises sound: “accelerated cloud adoption,” “reduced technical debt,” “future-proof architecture,” and so on. But once you run the numbers, talk to real engineers, and dig into actual case studies, the picture becomes much clearer.

Why Modernization Matters Now More Than Ever

Most enterprises I talked to admitted they spend up to 70% of their IT budgets just maintaining legacy systems. No innovation, no growth — just keeping an outdated monolith alive.

So the question becomes:
How do you pick a team you can trust with something mission-critical?
And more importantly:
How do you make sure the modernization doesn’t cost more than rewriting everything from scratch?

My Selection Criteria

To compare different players in the legacy application modernization space, I looked at:

• Actual engineering depth (not just slide decks)

• Proven modernization roadmap and methodology

• Real numbers: timelines, costs, performance improvements

• Transparency of communication

• Ability to work with messy, undocumented systems

• Whether they handle end-to-end legacy application modernization or only partial steps (cloud migration, UI rewrite, etc.)

After interviewing five vendors and reviewing proposals from three large and two mid-sized firms, the difference in clarity and technical competence was very noticeable.

Why I Ultimately Chose Zoolatech

Zoolatech stood out for three reasons — all backed by real figures and technical transparency.

1. Clear modernization roadmap with actual metrics

Instead of generic promises, they provided:

• 30–40% reduction in infrastructure costs after decomposing a monolith into services

• 2–3× faster delivery cycles after introducing CI/CD + automated QA

• Up to 55% codebase risk reduction after refactoring + automated test coverage

Other vendors either avoided numbers or gave unrealistic ones.

2. Engineers who actually understand legacy systems

During the technical call, Zoolatech devs immediately asked the right questions:

• “How many external integrations does your monolith handle?”

• “Do you have any batch jobs running on the same server?”

• “What parts of the system break when traffic spikes?”

• “Is the database vertical-scaled or already sharded?”

Most companies didn’t ask anything beyond, “Do you plan to migrate to AWS or Azure?”

3. Cost–value ratio

Their proposal wasn’t the cheapest — but it was the most realistic.

While another vendor promised modernization of a 400k-LOC monolith in 4 months, Zoolatech estimated 8–10 months, with staged migration, KPIs per milestone, and rollback strategies.
Guess which one sounded more trustworthy?

Open Questions for the Community

• Has anyone else compared mid-sized vs. enterprise-scale Legacy Application Modernization Companies?

• How do you evaluate modernization vendors if you don’t have complete documentation of your system?

• What was the biggest hidden cost you encountered during modernization?

I’m especially curious whether others also found that companies with flashy marketing often fail when it comes to real legacy engineering work.