What Is RPG AS400 Programming and Why It’s Used?

Designed by IBM, RPG (Report Program Generator) AS400 programming is a high-level, proprietary programming language. It is used across industries to build and maintain IBM i applications.

Core enterprise applications such as ERPs, CRMs, reporting systems, and accounting are built using RPG.

Businesses still rely on RPG programming language for its stability, complex transaction processing capabilities, and deep integration with IBM i ecosystems.

• Created in 1959, RPG has evolved from being a fixed format punch card code to modern free form ILE RPG
• Business rely on RPG for building, maintaining, and modernizing legacy business applications built for AS00 (now IBM i)
• It’s widely popular for building and maintaining enterprise-grade applications that demand complex data exchange with DB2 databases on IBM i
• Most common use cases of RPG are seen in manufacturing, finance, and retail industry where the transactions volume is is high
• Modern free-form RPG enables modular programming and is compatible with modern languages such as Java, Python, and SQL

And much more..

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What Is RPG AS400 Programming Used For?

RPG AS400 programming powers a wide range of mission-critical business applications running on IBM i.

Major use cases include –

• ERP applications for HR, supply chain, and finance
• Accounting and finance reporting applications
• Auditing, compliance and banking workflows
• Manufacturing and production planning
• CRM and order processing applications
• Inventory & warehouse management

These applications rely on RPG for consistent performance and accurate transaction handling.
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What Makes AS400 RPG Programming Relevant in 2026?

Until today, RPG still powers mission-critical applications for enterprises.

These applications are responsible for handling about thousands of transactions per second on a daily basis. They also support routine ops such as reporting, inventory management, compliance, etc.

RPG is not obsolete. It has evolved with time into newer versions such as RPG IV and free-form RPG to support SQL, modular programming, and API integrations. This enables compatibility for legacy systems to interact with modern applications without a rip-and-replace.

This consistent evolution and resilience make RPG indomitable today in 2026.

Why RPG AS400 Programming Still Matters?

• It’s risky and irrelevant to dump years of evolved business logic and replace it with newer tech
• It powers mission-critical applications for finance, manufacturing, logistics, and retail
• RPG support is still needed to maintain & upgrade legacy IBM i applications
• Support modernization through APIs and modern AS400 system integration approaches

What Modern Capabilities Does RPG AS400 Programming Support?

Modern RPG has evolved significantly beyond its traditional structure.

Today, RPG supports –

• REST APIs for connecting with modern applications
• Modular and service-oriented architecture
• Free-format syntax for easier development
• Cloud and hybrid system compatibility
• Integration with SQL and DB2 for i
• Automation of complex workflows

These capabilities allow you to modernize your existing IBM i applications without dumping them completely.

How is RPG Used in Business Applications across Industries?

RPG is predominantly used to build, maintain, and upgrade enterprise-scale business applications for high-performance data processing, database management, and complex batch processing.

It acts as a backbone for mission-critical applications running on IBM i across manufacturing, finance, retail, and logistics industries.

RPG IV and free-form RPG integrate with web services, REST APIs, and cloud platforms through modernization. This allows your legacy systems to communicate with modern apps and IT ecosystems.

• For banking and finance, it manages the account reconciliation, credit scoring models, and audit trails
• For retails, RPG applications manage everything right from inventory tracking to order fulfilment across locations
• For manufacturing, RPG applications account for material requirements, plant operations, and supply chain visibility
• For healthcare, RPG applications power claim processing and billing

How is RPG Used in Developing Financial & Accounting Applications?

In finance, accounting, or transaction-led environments, RPG AS400 programing is the preferred choice for building and running core financial processes.

It is entrusted for accurate, secure, and consistent data processing.

In most AS400 accounting software setups, how transactions flow, recorded, validated, and reported are controlled by RPG programs; right from general ledger to payroll calculations.

• Keepings records for invoices generated, and outstanding payments
• Calculating salaries, taxes, and standard deductions
• Real time recording of journal entries, sales, and payments
• Monitoring stock movements across locations against financial data
• Tracking audit trails and compliance standards

Why is RPG Still Used in Financial Systems?

• Pin-point accuracy and control across financial operations
• Reliable integration with DB2 for data storage and retrieval
• In-built validation rules for financial transactions
• Capability to handle high-volume transactions without failure
• Flexibility & support for modernization allows retention of business logic

RPG plays a pivotal role in keeping your financial operations stable. You can continue to extend it through strategic AS400 modernization solutions.

How is RPG Used in Developing Manufacturing & Inventory Management Applications?

In manufacturing and inventory-driven environments, RPG AS400 programming is widely used to build and run core operational processes.

It is relied upon for accurate tracking of materials, stock levels, and movement across the supply chain.

In most AS/400 inventory software setups, how inventory moves, gets recorded, validated, and updated is controlled by RPG programs, from raw material intake to finished goods dispatch.

• Real-time inventory tracking for goods moving through the system
• Production monitoring for workflows and material consumption
• Report generation for stock valuation and demand planning
• Record keeping for purchase orders, receipts, and suppliers
• Inventory cycles and batch traceability across system
• Stock monitoring for warehouses across locations

Why is RPG Still Used in Manufacturing Systems?

• High accuracy in tracking inventory and production data
• Strong integration with DB2 for i for consistent data handling
• Built-in logic for validation across supply chain operations
• Handles large volumes of transactions without breakdown
• Flexibility to extend existing systems through AS400 modernization solutions

RPG continues to support stable manufacturing and inventory operations while allowing businesses to modernize without disrupting existing workflows.
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Why is there a Growing Demand for AS400 RPG Programmers?

The number of experienced RPG AS400 programmers is declining slowly. Yet, there are businesses, still running their mission-critical IBM i applications built using RPG.

These applications are the backbone of core operations such as finance, inventory, ERP, and transaction processing. Replacing these applications involves complexities and risks. Thus, businesses are maintaining them as they are, or modernizing them instead.

Thus, the demand for skilled RPG programmers is on the rise.

The reason for the growing demand of RPG AS400 programmers is the high reliance on mission-critical business applications hosted on IBM i, and built using RPG.

Key Reasons for Rising Demand

• Many companies still depend on RPG-based applications for daily operations
• Experienced IBM AS400 programmers are retiring faster than new talent is entering
• Businesses prefer extending existing systems using APIs and integrations
• Years of embedded processes make RPG expertise essential for continuity
• Many companies need skilled AS400 programmers to maintain their legacy IBM i applications

For most companies, hiring skilled RPG developers is a resolve to ensure their mission-critical IBM i applications continue to function, and evolve with their operational needs.

That’s one of the reasons why companies are scouting to hire AS400 RPG programmers.

Why Can’t Decades of RPG Business Logic Be Replaced Easily?

Your RPG code doesn’t just run reports.

It holds years of embedded business rules, regulatory handling, edge case fixes, and operational logic.

Rebuilding all that from scratch? Risky. Time-consuming. Expensive.

Instead, more companies are opting for legacy system RPG support to preserve what works while adding modern capabilities.

Why Is There a Shortage of IBM iSeries Programmers?

A lot of IBM i expertise is walking out the door, literally.

Long-time developers are hitting retirement age, and businesses are realizing that knowledge transfer doesn’t happen by accident.

Bringing in experienced IBM iSeries programmers today helps plug that gap with minimal disruption.

Why Do Modernization Projects Still Depend on RPG Expertise?

Precisely, you can’t modernize it if you don’t understand it.

No matter if you are planning to integrate REST APIs or move the existing workloads to the cloud, you need someone who knows your RPG code inside out.

And, that’s where seasoned RPG developers strike an edge. They don’t rush to overwrite the whole, but they make it evolve with the changing business needs.

Why do Businesses Rely on External RPG Developers?

In-house teams are often tied up with user requests, system maintenance, and compliance audits.

They simply don’t have the capacity to dive deep into decades-old RPG code.

That’s why tapping into external RPG expertise, either through contractors or dedicated teams, has become a smarter move.

How Does RPG Programming Deliver Long-Term ROI?

This isn’t about holding onto legacy for nostalgia’s sake. It’s about preserving high-performing systems that deliver real ROI.

Strategic legacy system RPG support allows you to keep up with your existing systems while building compatibility with modern-day capabilities.

Running on RPG doesn’t mean you’re left behind. It simply means your technology has stood the test of time and is evolving.

The key is to find the right partners who understand that legacy isn’t a limitation. It’s a foundation.

And when you hire AS400 RPG programmers who know how to work with that foundation, you gain speed, resilience, and continuity that new platforms can’t replicate overnight.

Next, let’s understand the real-time impact of working with IBM iSeries programmers.

What’s the Real‑World Impact of Hiring AS400 RPG Programmers?

Still thinking if it would be wise to hire an AS400 RPG programmer with expertise?

Here are some real-world scenarios, where our AS400 RPG programming services proved to be pivotal in bringing the alignment between legacy and modern-day business computing.

Case Study – Modernizing a Legacy IBM i (iSeries) ERP for Magento 2 Integration

We helped Australia’s largest motorbike & accessories retailer modernize its legacy IBM i (iSeries) ERP and eCommerce ecosystem.

Their Magento M1-to-ERP integration relied on XML/FTP file transfers, creating security and efficiency bottlenecks.

We upgraded them to Magento 2 and redesigned the IBM i integration using APIs for faster, more secure, real-time data exchange.

This enabled new eCommerce capabilities while keeping core ERP processes stable and scalable for multi-location operations.

How Do RPG Enhancements Improve Business Performance?

A mid‑sized bank relied on RPG applications for transaction processing and reporting.

They needed to roll out a faster reconciliation module and support a new digital reporting format.

Through AS400 RPG programming services, our team of RPG programmers helped develop and deploy custom logic enhancements in under four weeks.

The outcome included faster settlements and reduced error rate by over 20%.

How Does RPG Support AS400 Modernization Projects?

A logistics company needed to upgrade a green‑screen WMS to integrate with their new web portal.

We translated their legacy RPG logic into free-form RPG, leveraged new APIs, and converted their inventory routines into modular.

Structured RPG code base modernization helped attain faster updates, better data visibility, and smoother integration with external systems like SAP.

How Does RPG Enable Integration with Cloud and Modern Systems?

A financial services firm wanted to process audit logs in real time and integrate them with their cloud analytics engine.

They relied on RPG programmers for financial services industry logic.

We created an integration bridge to translate their RPG batch logs to JSON via REST and sync with Azure data pipelines.

As a result, they now have real-time insights into compliance audits and improved visibility for auditors and leadership.

This shows, AS400 application development, when done properly, adds tangible business value while preserving the stability your operations depend on.
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Why Should You Choose RPG Programming over Modern Languages?

Choosing RPG programming over modern languages makes sense when your critical business operations are

Choosing RPG programming over modern languages makes sense when your business is heavily dependent on existing IBM i applications. Especially, modern free-form RPG lets you extend the value of your existing IBM i applications through modernization, without having to build everything from scratch.

When does RPG Makes More Sense?

• Existing business logic is already in place – Years of processes are built into current systems.
• Stability matters more than change – Critical operations need consistent performance.
• Lower risk approach – Enhancing current applications avoids large-scale migration risks.
• Strong data handling – Works closely with DB2 for i for reliable transaction processing.
• Supports modernization – Can integrate with APIs and modern applications.

RPG is not chosen instead of modern languages in every case. It is chosen when continuity, reliability, and controlled modernization matter more than rebuilding systems from the ground up.

We have been talking so highly about the programming language RPG; you might have a question in your mind, how can it be better than PHP or JavaScript for all the modern application development languages?

Your question has merit.

Choosing a legacy programming language in the modern age is like driving backward on a one-way street.

But our point is not about overlooking modern options but recognizing the unique advantages that AS 400 RPG brings.

Let’s dive deeper into understanding the uniqueness of the programming language RPG.

• When you use Java through WebSphere, it requires more hardware compared to RPG language, thus using RPG minimizes your maintenance and installation expenses.
• RPG provides one of the most interactive programming ecosystems. This means it facilitates easier management, smooth upgrades, and simplified integration capabilities.
• It becomes easier to work in AS400 with RPG. If you face any difficulties in the future with modern RPG language, you just need to upgrade it.
• SMEs and other organizations don’t always require fancy add-ons that PHP/WebSphere offers.

These are some highlighting features that help modern leaders lean towards AS400 RPG programming language to develop commercial business applications over other languages.

Now that you know why the programming language RPG stands out, you need professional RPG developers to handle your application development requirements.

We know what you are thinking. -”With the scarcity of RPG programmers, finding the right talent is challenging. And even if I find RPG developers, how do I ensure that they are the right fit?”

We heard you.

Here’s an unpopular opinion: The capable AS 400 programmers are available today, but not at the same rate as in the 1990s.

Proficient programmers play a crucial role in your AS400 RPG programming development.

Finding them is relatively easy if you have the right knowledge of the skilled programmers in place.

So which key skills should you keep in mind when hiring an AS-400 RPG programmer? Let’s find out.

What Skills should You Looks for in AS400 RPG Programmers?

Here are the top skills you should look for when hiring developers for RPG programming language.

Knowledge of Modern AS400 RPG Programming

From AS400 iSeries to IBM i Power Systems, your AS400 platform has evolved for the better. Alike, RPG has evolved from fixed-form RPG to free-form RPG ILE.

It’s a must for your AS400 RPG programmers to have witnessed these transitions. They should be well-versed with the modern form of RPG and the progression on-going.

If they lack the basics, they won’t be able to help maintain or upgrade RPG AS400 applications.

Practical Experience

Practical experience is one of the top-rated aspects for RPG programmers. It showcases their knowledge and skills before you hire them on board.

With proven experience in their toolkit, you can be confident that your team of RPG programmers has continually honed their skill set through RPG upgrades, delivering guaranteed results.

It better helps you understand your developer’s flexibility and adaptability to the dynamic landscape of the programming world.

While hiring, request details about the RPG developer’s past projects to better gauge the developer’s technical depth and the quality of their projects. This trusted approach provides valuable insights into their in-depth AS400 RPG programming skills and hands-on experience.

Problem-Solving

Beyond the technical skill set, it’s essential to explore the problem-solving capabilities of your prospective AS400 programmer.

To assess problem-solving abilities, pose an RPG development-related scenario, and seek a viable solution for it.

Having a creative problem solver on your side improves your chances of succeeding with an AS400 development initiative.

Great Communication

Having great communication skills is another important soft skill for your potential RPG programmers.

You as a leader, must strike an ideal balance between RPG developers with technical skills and programmers with soft skills for seamless communication and coordination.

It is ideal to have an excellent communicator who can paint complex RPG language codes most subtly for your non-technical stakeholders.

This will enable you to keep pace with the nuances of the entire project, ensuring you are in sync with both macro and micro application developments.

These are some of the top skills you should check in an AS400 RPG programming professional to filter the most qualified RPG candidates from the talent pool.
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Why Work with an AS400 Application Development Company?

It’s rare to find talent that genuinely understands IBM i, RPG, DB2, and CL workflows.

All you need is a technology partner who brings expertise, governance, discipline, and long-term commitment to the table, and not just coding nuances.

At Integrative Systems, we believe in helping you succeed first.

We are an AS400 Application Development Company built on years of successful delivery in BFSI, manufacturing and logistics.

Our teams offer as400 support and services, modernization roadmaps, and custom RPG development; all backed by domain knowledge and SLA commitments.

Our seasoned team of AS400 experts map your goals against our expertise and deliver structured AS400 solutions you can rely on. Our services portfolio includes AS400 support, modernization roadmaps, and custom RPG development.

Unlike inexperienced developers, our RPG experts are focused on delivering solutions that resonate with compliance, are scalable and grow with your future needs.

No matter if you’re extending existing applications through enhancements or seeking cloud enablement; we help you alike to gain clarity and control.

You can engage us for support, projects or long‑term modernization partnerships. We scale with you, and not just for project needs but for strategic growth.
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Why Choose Integrative Systems as Your Partner for AS400 RPG Programming?

Integrative Systems brings you a ready-to-deploy team of talented and professional RPG developers who have inherited all the top skills you need in a reliable team to deliver exceptional business-oriented applications.

We have dedicatedly helped companies and business leaders for 25+ years, such as you to resolve IT-related issues in their organization and ensure uninterrupted IT operations to achieve their business goals.

We demonstrate proper utilization of your allocated IT budget with positive ROI to your management and ensure you get the best user experience during the entire project development.

There’s more to our offerings.

We walk in with-

Agile Response to RPG Language Roadblocks

Our RPG programmers have in-depth knowledge of the technology and aim to give their best to deliver the most desirable results for your project.

We answer all your queries related to AS400 RPG programming, IBM iSeries infrastructure, and AS 400 systems with 24/7 customer support.

Budget-friendly

There are no fixed price brackets for every project requirement. We offer highly customizable development rates and flexible engagement models, while we deliver the highest-quality results within your budget.

Flexibility

If you completely want to outsource your iSeries requirements or want us to manage a dedicated wing, we bring extensive experience to the table. There are no limitations when it comes to the flexibility of our RPG programming language applications team.

Complete iSeries AS400 Solutions

With Integrative Systems, you get 360-degree solutions related to the IBM iSeries AS400. We empower you to escape the hassles of consulting multiple agencies for various AS-400 solutions. Be it AS400 applications modernization or management, we have done it all.

Still thinking?

Get in touch with our AS400 RPG experts at contact@integrativesystems.com for a complementary consultation and decide for yourself.

Experience the best application development based on AS400 RPG Programming in the United States by partnering with Integrative Systems.

About the Author

Mike Crowley

Director of Customer Success – IBM i

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Starting as an RPG programmer and evolving into a customer success leader, Mike has spent 30+ years shaping the IBM i landscape. His experience in IT, presales, and sales enables him to bridge business needs with technical depth. By simplifying even the toughest IBM i modernization challenges, Mike has become a trusted guide for enterprises nationwide.

He shapes smart account strategies and lasting customer relationships that lead to meaningful, sustained outcomes. At Integrative Systems, Mike guides customers through IBM i modernization with clarity and confidence. His steady, relationship-first approach unites teams, elevates customer experience, and drives long-term growth.