Fujitsu Launches Generative AI Service "Fujitsu Application Transform powered by Fujitsu Kozuchi" to Automatically Generate Design Documents by Analyzing Source Code

March 30, 2026
Fujitsu Limited

To support the modernization of enterprises and organizations, Fujitsu is launching "Fujitsu Application Transform powered by Fujitsu Kozuchi" as a SaaS service on March 30, 2026, in Japan. This service utilizes generative AI to analyze source code, including COBOL, within existing legacy systems and automatically generate design documents to understand the content of these existing systems.

The need for system modernization is growing among companies and organizations to enhance their competitiveness and respond quickly to environmental changes. However, a major hurdle in promoting modernization is that legacy systems, due to years of operation, often have outdated design documents. The overall system structure and detailed specifications become black boxes, requiring significant cost and time to decipher and analyze. Furthermore, there is a shortage of experts familiar with legacy systems. Modernizing mainframe systems, in particular, has been challenging due to the vast amount of COBOL code, with various coding styles accumulated over approximately 40 years, making analysis difficult.

To solve these challenges, Fujitsu is launching "Fujitsu Application Transform powered by Fujitsu Kozuchi," which leverages its long-cultivated system development expertise, proprietary technologies, and generative AI.

As a proprietary technology, this service utilizes code analysis techniques on remaining design information and existing programs. By managing Retrieval-Augmented Generation (RAG) with "Fujitsu Knowledge Graph Extension RAG for Software Engineering," it links vast amounts of source code to prevent omissions and hallucinations, automatically generating design documents with high analytical accuracy and readability.

Building on the track record of its predecessor, "Design Document Reverse Service for Application Assets," launched in February 2025, Fujitsu has standardized its analysis technology and design document generation know-how. This has led to the launch of "Fujitsu Application Transform powered by Fujitsu Kozuchi," which allows customers to perform analysis tasks themselves.

This service can reduce the time required for tasks ranging from understanding programming languages, which previously took human effort over extensive periods, to generating design documents, by approximately 1/30, even without expert knowledge. Compared to analysis using only standard generative AI, our proprietary technology generates consistent design information from existing system source code without omissions. This enables automatic generation of design documents without omissions even for difficult-to-analyze COBOL languages, improving comprehensiveness by 95%. These accuracy improvements also lead to a 60% increase in the readability of design documents compared to conventional methods, confirming the generation of high-quality design documents.

In the future, Fujitsu plans to offer services such as implementation support for this service. Furthermore, in addition to automatic design document generation, functions for rebuilding existing assets' source code for future use, automatically rewriting source code, and supporting operations and maintenance are planned for phased release from fiscal year 2026 onwards. Through these services, Fujitsu aims to strongly support the understanding of current system specifications and characteristics by generating high-quality design documents, as well as the formulation and execution of modernization and migration strategies for systems.