Legacy System Modernization
Your systems work. They just need to work better. For 20 years, Coalesce has helped companies modernize without starting over: reducing risk while shipping real improvements.
Since 2006
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$125M+ client revenue supported
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4+ year avg. client relationship
You don't need a rewrite. You need a team that can untangle what you have, identify what's worth keeping, and systematically improve the rest. We specialize in brownfield development: making existing systems faster, more maintainable, and ready for what's next.
When "rebuild from scratch" isn't the answer
Every agency wants to pitch you a greenfield rewrite. It's more billable hours, and they don't have to learn your codebase. But rewrites are risky, expensive, and often fail. There's a better way.
Your system has years of business logic baked in.
That "messy" codebase represents thousands of decisions about how your business actually works. A rewrite doesn't just replace code. It forces you to re-learn lessons you've already paid for. We'd rather build on what you know.
You can't pause the business while you rebuild.
Your team needs to keep shipping features. Customers need the system to stay up. A two-year rewrite means two years of maintaining parallel systems and delayed roadmaps. Incremental modernization lets you improve while you operate.
Your developers are tired of fighting the codebase.
Slow builds. Flaky tests. Fear of touching certain modules. Technical debt compounds until every change feels risky. We help you pay it down strategically, so your team can move fast again.
Services
Technical Assessment
A focused audit of your codebase, infrastructure, and pain points. We identify what's working, what's blocking you, and where to start.
Incremental Refactoring
Systematic improvements to code quality, architecture, and maintainability without stopping feature development.
Database Modernization
Schema optimization, query performance, and migration to modern data infrastructure when needed.
API Layer Development
Wrapping legacy systems with modern APIs so new applications can integrate without touching old code.
Cloud Migration
Moving from on-premise or outdated hosting to scalable cloud infrastructure, without downtime.
Security & Compliance Updates
Addressing vulnerabilities, updating dependencies, and meeting current compliance requirements.
Process
1. Discovery
We start by understanding your business: goals, constraints, existing systems (if any), and what success looks like. No 200-page audits.
2. Strategy
A prioritized roadmap based on your constraints. What's urgent vs. important. What we can ship in weeks vs. what needs architectural work. Clear trade-offs, not hand-wavy estimates.
3. Build
AI-augmented development with human review at every decision point. Whether we're starting fresh or working in your existing stack, you get senior engineers. No handoffs.
4. Launch
QA, deployment, and monitoring. We don't ship and disappear.
5. Iterate
Ongoing partnership, not a handoff. We stick around to make it better.
Recent Case Studies
Coalesce brought a rigorous development approach, meticulous attention to detail, and creative suggestions to the process. The team was clearly invested in the project's success and has become a trusted, valuable collaborator.
Morgan Brown
Inman News
FAQ
What industries do you work with?
We've modernized legacy systems in Financial Services, Healthcare, Education, Real Estate, Publishing, and Enterprise SaaS. The patterns are similar across industries: aging codebases, technical debt, and the need to move faster.
How long does a typical modernization project take?
It depends on scope and complexity. A technical assessment takes 2-4 weeks. Focused modernization sprints run 2-3 months. Larger transformations are ongoing partnerships, often 6-18 months. We'll give you a realistic timeline after discovery.
Do you replace our existing system or improve it?
We improve it. Our approach is incremental modernization, not rip-and-replace. We identify the highest-impact areas and address them systematically while your system stays running. Full rewrites are rarely the right answer.
What technologies do you work with?
We're language-agnostic. We've modernized systems built in PHP, Python, Ruby, Java, .NET, and Node.js. The approach matters more than the stack. We'll work in whatever your system is built on.
Where is your team located?
We're headquartered in New York City, with senior engineers across the Americas and Europe. Our distributed team means faster turnaround without sacrificing quality or communication.
How do you price projects?
Most engagements start with a focused discovery phase, then move into monthly retainers for ongoing development and support. We scope work as fixed-fee or monthly retainers depending on the nature of the project. Full builds vary based on complexity. We're not optimizing for one-off projects. We partner with teams who want a long-term engineering relationship.
Ready to modernize without the risk?
We support $125M+ of client revenue annually with a lean team of senior engineers. Let's talk about what's slowing you down.