Kato Integrations
By Developers, For Developers

Build REST APIs
Using Only RPG

Build and expose REST APIs on IBM i using 100% native RPGLE. No Java. No middleware. No open source risk. Works on OS versions 7.1–7.6.

IBM i iSeries AS400 RPGLE
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APIs Built in RPGBuild custom APIs using 100% native RPG
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Call Web ServicesRetrieve partner data over HTTP
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No Java, No MiddlewarePure RPG — no slow boot times
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Expert Support IncludedEvery license backed by our team

Try a Free Proof of Concept

Test RPG API Express in your own IBM i environment — 100% free, fully featured 30-day trial.

  • No credit card or purchase required
  • We deploy a working proof of concept in your IBM i environment
  • Our team guides you through setup every step of the way
🌍Trusted by IBM i teams in 50+ countries
⭐98% customer retention rate
🏆25+ years of IBM i expertise
APIs Built in RPG
100% native RPGLE
Call Web Services
REST & SOAP support
Offer REST APIs
Let partners access your data
Create JSON + XML
Structured data generators
Parse JSON + XML
Extract to DB2 fields
Expert Support
Every license backed by us
Modernize your IBM i

Take the best of IBM i and build on it

Modernization doesn't mean abandoning what works. RPG API Express helps your business unlock the true potential of the RPG language — no ripping and replacing, just extending what you already have.

  • Integrate any API with REST & SOAP capabilities
  • Capture partner data with JSON & XML creation and parsing
  • Develop in 100% RPG without relying on drivers and middleware
Developer at laptop writing code
Simplify your development

A unified library of commands and subprocedures

RPG API Express is a library of commands and subprocedures designed to simplify and streamline RPG-based API development. Build applications faster with utilities, code generators, and a vast array of powerful tools.

  • Generate JSON & XML subprocedures
  • Develop programs using a unified API of connected functions
  • Leverage CCSID conversion, MD5 & SHA hashing, and Base64 encoding
Developer working across multiple monitors
Build fast, responsive systems

Gone are the days of waiting for Java to boot

RPG API Express is built using 100% RPG, optimizing your development and providing lightning-fast responses. RPG API Express utilizes the IBM i to its fullest capacity — no JVM overhead, no middleware latency.

  • Save hours of development time
  • Build faster using API documentation with example programs and tutorials
  • Supports OS versions 7.1 through 7.6
Server infrastructure and circuit board
Backed by expert-level RPG developers

Production support from a team that knows RPG

RPG API Express is the ultimate supported API solution — you'll have access to a diverse team of seasoned RPG programmers to solve every one of your needs, not just a ticket queue.

  • Development questions answered by people who know RPG
  • Support during critical transitions, not just onboarding
  • Don't risk it with open source — have a production-ready team behind you
Development team collaborating at workstations
RPG API Implementations
Connect to the APIs you already use

RPG API Express has been used to connect IBM i systems to dozens of real-world APIs. Here's a sample of what your team can integrate with out of the box.

Google Maps API
FedEx Shipping
Salesforce CRM
PayPal Payments
Experian Data
Amazon AWS
SugarCRM
WordPress REST
Adobe Commerce
TaxCloud
YRC Freight LTL
Descartes Fleet
Customer Stories
What IBM i developers say
★★★★★
We successfully consume UPS web services to create electronic return labels. This is the best package support I've received from my 15 years of IBM i/AS400 experience.
Alla Ginzburg Fidelitone
★★★★★
With the help of RPG API Express I was able to cut my personal project time in half. It runs natively in RPG with Apache giving it excellent performance.
Bruce "Hoss" Collins Houston County, Alabama
★★★★★
RPG API Express enables us to communicate from our IBM i in real-time with our credit vendors, and the implementation was quick and easy. I would recommend it to anyone.
Margaret Yung Spartan Insurance
★★★★★
I followed some example code on your website and have a simple app up and running very similar to what my client needs. Your software is making me look like a hero!
Carl Galgano EDI Consulting
How it works
Your free proof of concept in 3 steps

This isn't a self-serve download — it's a guided, hands-on process. Here's exactly what happens after you submit the form.

1

Define Your Problem

Send us your API documentation and internal requirements. Our team will determine the best course of action for your specific use case.

2

Develop a Program

With your requirements in hand, our RPG developers build a callable, deployable program tailored specifically to your IBM i environment.

3

Deploy a Solution

See RPG API Express in action in your own environment. You'll also receive a fully-featured 30-day trial license to keep exploring.

RPG development is a hard job.
Let us make it easier.

Ready to get started? Submit the form and our team will be in touch to kick off your free proof of concept.

No credit card required · No purchase commitment · Guided by our team