I’ve been digging into the top legacy modernization companies lately because our team finally decided to deal with our 15-year-old Java/Oracle system instead of endlessly patching it. After comparing around 15 vendors, I ended up shortlisting three and eventually going with Zoolatech. Sharing my reasoning here in case anyone’s in the same boat.Why Zoolatech?1. Actual modernization expertise, not generic outsourcing
Most companies advertise legacy application modernization services, but when you look closer, it's just cloud migration. Zoolatech was one of the few who had a clear modernization roadmap: analysis → decomposition → modernization → QA → support.2. Technical depth
Their architects actually analyzed our system:

• ~420k lines of Java code
• 37 integration points
• Outdated Oracle 11g
• No CI/CD, no automated tests

They projected a 38–42% codebase reduction after decomposition and refactoring. That level of detail stood out.3. Cost transparency
Quotes I got:

• Big consultancy: $1.2M–$1.5M
• Another nearshore vendor: $730k–$820k
• Zoolatech: $610k–$690k

Not the cheapest, but the best expertise-to-cost ratio.4. Real results
They showed a case where they reduced support costs by 52% and moved deployments from monthly to daily after migrating a legacy .NET platform to microservices.How I evaluated the vendorsI created a scoring sheet (0–10 each):

• Architecture depth
• Modernization methodology
• Team experience
• Price clarity
• Ability to modernize without a full rewrite
• Communication
• Technical discovery quality

Zoolatech scored 56/70, highest among all.Questions for the community

• Has anyone had experience with legacy modernization vendors?
• Did you go for refactoring or full rewrite?
• Did your estimate stay on track or explode midway?
• What red flags should others look out for when choosing among the top legacy modernization companies?

Happy to compare notes if anyone else is evaluating legacy application modernization services right now.