REVAPI: How to Call Any External API from Your Mainframe or AS400
Generate a compiled COBOL client from any OpenAPI spec and call modern APIs directly from your Mainframe or AS/400. No middleware. No manual JSON parsing.
REVAPI by OpenLegacy auto-generates a ready to use COBOL client from any Open API spec so your mainframe programs can call modern services without custom communication layers, manual JSON handling, or weeks of development.
The Missing Link in Phased Migration
Phased migration is the right approach for modernizing mainframe systems. Don't rip and replace. Don't freeze your core systems for a multi-year rewrite. Instead, extract components incrementally — migrating business operations piece by piece while keeping the mainframe running and stable.