LegacyBridge: Session-Aware API & Event Adapter for AS/400 and 4GL Systems
9/10
Demand Score
Incompatible legacy systems block ERP rollouts and integrations; exposing safe APIs now unblocks programs without risky rewrites.
7/10
Blue Ocean
Competition Level
$3k-12k
Price/Month
Predicted customer spend
10 days
Time to MVP
Difficulty: Hard
The Problem
A lightweight agent and cloud service that turns green-screen, 4GL, and proprietary legacy transactions into safe, modern APIs and events without rewriting. LegacyBridge learns screen flows and state
🔗 Validated by Real User Complaints
This problem has been verified through 3 real user complaints:
Competitor Landscape
- OpenLegacy
- Rocket API
- IBM z/OS Connect
- Micro Focus (Modernization)
- KrononSoft (screen wrappers)
Must-Have Features for MVP
Agent-based screen/state recorder and mapper
Automatic API generation with OpenAPI/GraphQL
Transaction boundary detection and rollback handling
Idempotency keys and session affinity
Field normalization, code-page and UoM translators
Event emission (Kafka, Pub/Sub) for downstream sync
Policy layer for rate limits, authN/Z, and PII redaction
Observability: per-flow latency/SLA, replay, and audit
⚠️ Potential Challenges
- Deep variability of legacy screens and error conditions
- Handling multi-step transactions with partial failures
- Security hardening and mainframe change approvals
- Performance tuning for high-throughput API calls
Risk Level: Moderate
🎯 Keys to Success
- Ship first API in days via visual mapping, not code
- Eliminate brittle RPA by using session-aware adapters
- Sustain ERP integration velocity without legacy rewrites
- Reduce incidents via built-in idempotency and retries
- Demonstrate measurable lead-time reduction for integrations
Ready to Build This?
This hard-difficulty project could be your next micro-SaaS success.