IBM i — Modernization
IBM i Modernization Without Losing What Already Works
This is core IBM i work: taking RPG and COBOL applications that have run your business for decades and bringing them forward — free-format code, modern integrations, a web front end — without forcing a rewrite of logic that already works.
What modernization covers
Bringing Legacy IBM i Applications Forward, Piece by Piece
Modernization doesn’t mean starting over. Most of the engagements below run alongside the application you already have, not instead of it.
Our approach
Modernization: Preservation Meets Performance
You don’t have to abandon a reliable IBM i or AS/400 system — you need to modernize it strategically. We work with companies running legacy RPG-based ERP systems, helping them stabilize what they have and build a realistic plan for the next three years of growth, not just the next release.
That means improving the experience for the people using the system every day — moving off the green screen where it makes sense — and introducing modern functionality, all while keeping your core business logic, your existing data, and your budget intact.
Where to start, and how far to go, comes down to balancing opportunity against budget and what actually moves the needle for your business. That’s the strategy conversation we have before any code changes.
What We Balance
- User experience — a modern interface your team actually wants to use
- Core business logic — the rules that already work, left alone
- Existing data — no migration, no re-platforming
- Budget — a plan scoped to what you can actually spend
Why incremental, not a rewrite
A Full Rewrite Is Usually the Wrong Answer
The instinct when RPG code looks old is to throw it out and start over. In practice, a full rewrite means re-testing every business rule your current system already gets right, on a timeline measured in years, with the people who understood the original logic often long gone.
Paragon modernizes in place instead. We convert fixed-format code to free-format ILE RPG, add a web front end, or build an API layer — each step ships on its own, each step is testable on its own, and the application keeps running production while it happens.
Our approach to this is covered in more detail in RPG Modernization Without a Rewrite. When modernization work coincides with an OS upgrade, we plan both together using our IBM i OS upgrade checklist.
This work sits alongside the rest of what we do under software development — and for clients who want the system assessed first, it often starts as IBM i consulting.
Code & Documentation Audit
We inventory your programs, objects, and job dependencies, and flag what’s undocumented or fragile before touching anything.
Modernization Roadmap
A prioritized, staged plan — which programs convert first, where a web front end pays off fastest, what can wait.
Incremental Conversion
Each stage — a conversion, an API, a front end — is built and tested against the current system before it goes live.
Testing & Handoff
Regression testing against known outputs, then documentation and knowledge transfer so your team owns what changed.
API strategy
API Strategy: Unlocking New Revenue and Productivity
APIs are becoming table stakes for staying competitive. They let you expose what your RPG and COBOL applications already do — to a new web front end, a partner integration, or an ERP system — without touching the application logic underneath.
Done well, an API layer opens new revenue channels, cuts the manual work your team spends moving data between systems, and reduces the overhead of maintaining one-off integrations.
We start by identifying the highest-impact, fastest-to-implement opportunity — not the most ambitious one — so you see results before committing to a larger program. From there, we connect APIs directly to your existing RPG and COBOL code, working with partners like Eradani where they’re the right fit, to extend what your system can do without a rewrite.
Before you call
Undocumented, Fixed-Format, and Twenty Years Untouched Is a Normal Starting Point
Most modernization engagements start with code nobody currently on staff wrote, in a dialect nobody’s taught anymore. That’s not a blocker — it’s the usual starting point, and it’s exactly what the audit phase is for.
FAQ
Modernization Questions
Do you rewrite everything from scratch, or modernize in place?
In place, in almost every case. We convert and extend existing RPG and COBOL rather than replacing it outright — a full rewrite is rarely the right trade-off in cost, risk, or timeline.
What’s the difference between free-format and fixed-format RPG?
Fixed-format RPG (RPG III/IV) uses column-specific syntax that’s hard to read and maintain. Free-format ILE RPG reads closer to a modern programming language while producing the same results — it’s what makes the code maintainable by developers who didn’t write the original.
Can you modernize code with no documentation and no original developer?
Yes — this is the majority of what we’re called in for. The audit phase exists specifically to reconstruct that missing context before any conversion work starts.
Can we get a web front end without touching the core system?
Yes. We regularly build browser-based front ends in PHP or Java that sit on top of your existing RPG and DB2 data, with no changes to the underlying application required.
How long does a modernization project take?
It depends on scope, but because we work in staged increments rather than a single rewrite, the first piece — often a targeted RPG conversion or a single web front end — is usually live in weeks, not years.
Ready to Modernize Your IBM i Applications?
Tell us what you’re working with and we’ll give you a realistic, staged plan — not a proposal to rebuild everything.
Discuss your modernization project Call 800-966-6725