Comparison
Moderne vs OpenRewrite: a platform on top of an open-source engine.
The question is not which is better. It is whether your estate is big enough that running recipes by hand stops working.
The short answer
OpenRewrite is the open-source engine that runs recipes against code. Moderne is a commercial platform from the creators of OpenRewrite that runs those recipes across many repositories at once, with search and tracking. A single application rarely needs the platform. A large estate often does.
Basics
How are Moderne and OpenRewrite related?
OpenRewrite is an open-source refactoring engine. It reads code into a tree, applies recipes and writes the result back. See OpenRewrite recipes for Java 21 and Spring Boot 3 for how that works.
Moderne is a separate commercial product built by the team behind OpenRewrite. It adds a way to run recipes across hundreds or thousands of repositories, browse the results and manage the changes. This page describes Moderne from its public documentation. Ace8 has not run a benchmark on Moderne, so we do not report hands-on results for it.
Side by side
What does each one give you?
Check the vendor's current documentation before relying on any row. Product features change.
| Capability | OpenRewrite (open source) | Moderne (commercial platform) |
|---|---|---|
| Run recipes on one repo | Yes, through Maven or Gradle plugins | Yes |
| Run recipes on many repos | You script it yourself | Built in, as described by the vendor |
| Search code across the estate | Not provided | Provided, per vendor documentation |
| Track which repos have changed | You build it | Provided, per vendor documentation |
| Cost | No licence fee; engineer time | Commercial; ask the vendor for terms |
| Custom recipes | Yes | Yes, with platform tooling |
| Review of every diff | Required | Required |
Stay with the engine
When is plain OpenRewrite enough?
- You are upgrading a handful of applications, not hundreds.
- Your build is standard Maven or Gradle and runs in CI you already have.
- You are comfortable reviewing a patch and running the tests yourself.
- You want no new vendor relationship for a one-off upgrade.
Consider the platform
When does a platform start to pay off?
The pressure shows up at scale. Coordinating the same upgrade across a hundred repositories, owned by many teams, means tracking which ones are done, which failed to build and which need a custom recipe. Doing that with scripts and spreadsheets is possible and tedious.
That is the case where a platform may earn its licence. Count the repositories and the teams first. If the number is small, do the arithmetic before buying anything.
Pricing
What should you ask about Moderne pricing?
We do not publish Moderne's prices, and they are not ours to state. Ask the vendor these questions in writing.
- What is the unit: repositories, lines of code, seats or developers?
- What happens to the price as the estate grows?
- Which recipes are included, and which carry separate licence terms?
- Can recipes run inside our network, or does code leave it?
- What does the contract allow if we stop using the platform?
Alternatives
What are the alternatives to Moderne?
See AWS Transform vs OpenRewrite for the AI side of that choice.
- Plain OpenRewrite, scripted across repositories, with your own tracking.
- An AI-assisted tool for what recipes miss, such as AWS Transform or GitHub Copilot app modernization.
- A services engagement where an engineering team runs the recipes and the review for you.
How we work
How does Ace8 use these?
Ace8 is the AI-assisted application modernization practice of AceMQ. We run OpenRewrite recipes first, then AI-assisted tools on what remains, then tests and engineer review. For a client with a large estate we would decide with you whether a platform is worth the licence. The assessment counts the repositories and sizes that decision.
No. OpenRewrite is the open-source engine. Moderne is a commercial platform from the same creators that runs recipes at scale.
The OpenRewrite engine is open source. Licence terms for individual recipe modules can differ, so check the terms of each one you use.
Pricing is set by the vendor and is not published here. Ask about the pricing unit, growth and included recipes.
Not for one or a few applications. OpenRewrite alone can run the recipes. A platform matters when you coordinate the same change across many repositories.
We make no partnership claim. This page is based on public documentation.
Know the cost before anything moves.
A fixed-price assessment gives you the inventory, the risk score and a phased plan. Scope and cost are fixed before the migration starts.
Book a Fixed-Price AssessmentGet in touch
Talk to a modernization engineer
Tell us what you run today. An engineer, not a sales script, replies within one business day.