OpenAI outlines five-phase COBOL modernization with GPT-5.3-Codex

OpenAI's Codex Cookbook documents a five-phase COBOL modernization workflow using GPT-5.3-Codex: inventory, business-rule extraction, migration artifacts, code generation and parity testing. OpenAI says the model speeds up analysis and testing but does not replace human review during migration.

• Workflow covers inventory, rule extraction, artifacts, code generation and parity tests
• Codex is available via the app, CLI and IDE integrations
• The model does not complete migrations autonomously; engineer review is required
• No equivalent formal workflow is documented for Fortran or Visual Basic