LegacyLift Sidecar Gateway (Non‑invasive APIs for AS/400 & Mainframe)
10/10
Demand Score
Critical business logic is trapped in legacy systems; teams must integrate quickly without rewriting or destabilizing core apps.
8/10
Blue Ocean
Competition Level
$3k-20k
Price/Month
Predicted customer spend
16 days
Time to MVP
Difficulty: Expert
The Problem
Legacy System Integration:
Competitor Landscape
- OpenLegacy
- Rocket API
- IBM z/OS Connect
- UiPath/Automation Anywhere (RPA)
- Cleo Integration Cloud (legacy connectors)
- MuleSoft/ Boom i legacy connectors
Must-Have Features for MVP
Protocol-level 5250/3270 modeling into deterministic state machines
Auto‑generated REST/GraphQL with OpenAPI and SDKs
COBOL copybook and DDS parsers to typed JSON
CDC via IBM i journals and file watchers
Transactional safety (idempotency, rollback)
Record/replay virtualization for CI and partner testing
⚠️ Potential Challenges
- Host security approvals and network constraints
- Variability in green‑screen flows across tenants
- Throughput/latency constraints on host systems
- Licensing limits on terminal/session counts
Risk Level: Moderate
🎯 Keys to Success
- Zero code changes to host systems
- Stable APIs that survive UI changes
- Provable reliability under load
- Fast time to first endpoint (<2 weeks)
Ready to Build This?
This expert-difficulty project could be your next micro-SaaS success.