Moderne

Moderne: Deterministic Code Change Across 100,000 Repositories

Moderne is the commercial platform from the creators of OpenRewrite, the open-source refactoring engine CEO Jonathan Schneider started at Netflix. Where AI coding assistants generate probabilistic suggestions one file at a time, Moderne applies deterministic, compiler-accurate transformations across an entire code estate — the same fix lands identically whether it touches one repository or 100,000.

The technical core is the Lossless Semantic Tree (LST), a full-fidelity code model that captures types, formatting and semantics, making transformations safe enough to run unattended at scale. On top of that sits a library of more than 10,000 composable recipes spanning 40+ domains and 10+ languages — framework migrations, security patches, API upgrades — plus an agent layer that lets AI coding agents drive accurate change through the same machinery. It ships as a SaaS platform, an air-gapped on-premises deployment (Moderne DX), or a fully managed remediation service.

Key Features

• Lossless Semantic Tree — compiler-accurate code representation enabling type-aware, deterministic transformations
• 10,000+ recipe library — pre-built migrations and fixes across 40+ domains and 10+ languages
• Mass-scale execution — one recipe run applies consistently across thousands of repositories
• Agent tools layer — high-speed code search and transformation primitives that ground AI coding agents in accurate change
• Flexible deployment — SaaS, air-gapped Moderne DX, or a fully managed remediation service
• OpenRewrite foundation — open-source engine with roughly 3,600 GitHub stars, embedded in major vendor tools

Ideal Use Case

Moderne fits platform-engineering and application-modernization teams at large enterprises facing framework upgrades (Java, Spring, etc.), security remediations and tech-debt paydown across sprawling codebases. A cited example: one Log4Shell remediation fixed 38,000 call sites across 400 repositories with zero regressions.

How Moderne differentiates

Moderne closed a $30 million Series B in February 2025 led by Acrew Capital (roughly $50 million raised in total), grew its customer base 250% in 2024 with Fortune 500 customers including Walmart, Allstate and Choice Hotels, and its OpenRewrite engine is integrated into AWS's Amazon Q, Microsoft's GitHub Copilot and Broadcom's App Advisor. Gartner named Moderne a Visionary in its inaugural Magic Quadrant for Technical Debt Management Tools.

FAQ

What is the relationship between Moderne and OpenRewrite? Moderne created and maintains OpenRewrite, the open-source refactoring engine. The Moderne platform runs OpenRewrite recipes at organizational scale with search, orchestration and reporting.

Is OpenRewrite free? Yes — OpenRewrite is open source and free to run per-repository. Moderne's paid platform adds mass-scale, multi-repo execution and management.

How is Moderne different from AI coding assistants? Assistants generate probabilistic edits; Moderne applies rules-based, compiler-accurate transformations that behave identically everywhere, and exposes tools so agents can use that accuracy.

What languages does it support? Recipes cover 10+ languages, with deep support for Java and JVM frameworks and expanding coverage including Python.

tl;dr

Moderne turns OpenRewrite into an enterprise platform for deterministic, mass-scale code migration and tech-debt remediation — backed by $30M in Series B funding and trusted by Walmart, Allstate and the tools of AWS and Microsoft.

Related

Looking for more options? Browse the Developer Tools directory or read our best AI coding tools listicle. Moderne is also tracked on Crunchbase.