Legacy Modernization · API Development

Unlock your legacy data without replacing the system.

Q: Can this work with AS/400 (IBM i)?

Yes. We build APIs on top of AS/400 using ODBC/JDBC connections to DB2/400, data queues, program calls, and IFS file interfaces. Your AS/400 data becomes accessible via standard REST APIs.

Q: Is this a permanent solution or just a bridge?

It can be either. Some organizations use the API layer as a permanent integration strategy. Others use it as a bridge during phased migration -- decoupling consumers from the legacy system so it can be replaced without disrupting integrations.

Q: What about write operations back to the legacy system?

We support both read and write APIs. Write operations use the legacy system\'s own transaction mechanisms (stored procedures, program calls) to ensure data integrity and business rule enforcement.

Your legacy system holds critical data that modern applications need -- but it has no APIs, no webhooks, and no modern integration points. We build a REST/GraphQL API layer on top of your legacy system so new applications can access data without touching the core.

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4fit signals

6scope modules

5delivery stages

Operations layeroperating layer

The Problem

Legacy Systems Are Data Prisons

Build a modern API layer on top of legacy systems so new applications can integrate without touching the core. Unlock your data without the risk of a full replacement.

Modern applications can\'t integrate because the legacy system has no APIs or web services

Data extraction requires custom file exports, screen scraping, or direct database queries

Every new project requires a bespoke integration that takes weeks and is fragile to maintain

The data you need for BI, automation, and customer portals is locked inside a system that can\'t share it

Scope

What this service has to produce.

The work is organized as modules because implementation scope should be visible before the build starts.

RESTful API Design

Clean, documented REST APIs that expose legacy data and operations. Standard HTTP methods, JSON responses, and OpenAPI/Swagger documentation.

Data Abstraction

Abstract legacy data models into modern, clean interfaces. Consumers see logical business objects, not cryptic legacy table structures.

Real-Time & Batch

Real-time APIs for transactional operations plus batch endpoints for bulk data extraction. Match the integration pattern to the use case.

Authentication & Authorization

OAuth 2.0, API keys, and role-based access control. Secure access to legacy data with modern security standards.

Rate Limiting & Caching

Protect legacy systems from being overwhelmed by API traffic. Intelligent caching reduces load on the legacy system while keeping data fresh.

Monitoring & Logging

API usage dashboards, error tracking, and performance monitoring. Know who\'s calling what, how often, and whether it\'s working.

Architecture

The service has to fit the operating layer it touches.

Operations layerWhich manual workflow is costing the most time, rework, or decision delay.

Governance dependencyThe workflow needs clear ownership, trusted data, and exception rules before automation is worth building.

Operating data involved

orders

approvals

documents

exceptions

reporting handoffs

What we check before implementation

Which system owns the record of truth.
Where manual work or reconciliation enters the workflow.
Which integrations, rules, or data cleanup have to come first.

Delivery sequence

How the work moves from diagnosis to production.

Your legacy system holds critical data that modern applications need -- but it has no APIs, no webhooks, and no modern integration points. We build a REST/GraphQL API layer on.

API Requirements

Define which data and operations need to be exposed. Prioritize by business value -- what integrations are blocked today?

Legacy System Analysis

Analyze how to extract data from the legacy system -- direct database, stored procedures, file interfaces, or screen automation.

API Design & Build

Design API contracts, build the middleware layer, and implement data mapping between legacy formats and modern JSON/REST.

Testing & Security

Load testing to ensure legacy system stability, security testing, and integration testing with consuming applications.

Documentation & Onboarding

Publish API documentation, developer guides, and sample code. Onboard internal teams and third-party integrators.

FAQ

Questions that usually decide the scope.

These answers help separate a real implementation plan from a generic technology discussion.

Will the API layer slow down our legacy system?

We design the API layer to minimize impact -- read replicas for queries, connection pooling, caching, and rate limiting. Most legacy systems handle API traffic with no noticeable performance impact.

Can this work with AS/400 (IBM i)?

Is this a permanent solution or just a bridge?

What about write operations back to the legacy system?

Next step

Start with the operating problem, then sequence the build.

Metrotechs maps the record, traces the workflow, identifies the leakage, and turns the scope into a practical plan for Odoo, AWS, data, automation, portals, and AI.

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Built around real records, workflows, governance, and production handoffs.

Scoped to what can be implemented, owned, and operated after launch.