Mainframe systems continue to power critical enterprise operations, but maintaining, modernizing, and transitioning them requires deep operational understanding. GBT provides Mainframe application support, managed services, modernization, migration, and decommissioning solutions aligned to business continuity and long-term transformation goals. From legacy application maintenance to phased migration and retirement strategies, we help organizations reduce dependency on aging systems while ensuring operational stability and minimal disruption.
Mainframe challenges don't all look the same. Tell us where you are.
Keep the logic. Change everything around it.
Modernisation is not the same as migration. Some workloads belong on the Mainframe, but the COBOL code, the batch-only interfaces, the lack of API connectivity, and the absence of modern DevOps practices make those workloads harder to maintain and impossible to extend.
GBT modernises the layer around your business logic APIs, interfaces, databases, and delivery practices while preserving the core that your operations depend on. The result is a Mainframe environment that can participate in a modern architecture, not sit isolated from it.
Move off mainframe. Without moving the risk with you.
Migration is not a lift-and-shift exercise. The business logic embedded in a COBOL application that's run for 20 years doesn't move cleanly without assessment, sequencing, and validation. Organisations that treat it as a technical cutover, not a business-critical programme, are the ones that experience production incidents.
GBT's migration approach starts with assessment, not assumptions. We map what you have, sequence what should move first, define dependencies, and build rollback strategies before the first workload is touched. Decommissioning is planned alongside migration — including legacy system shutdown, archival strategy, dependency cleanup, access retirement, and operational transition — so environments are not just moved, but fully stabilized and responsibly retired.
Client Outcome
A financial services enterprise with a COBOL-based batch processing system unmodified for 14 years engaged GBT for a full assessment before committing to any migration spend. GBT delivered a complete workload dependency map, a phased roadmap to AWS, and managed the first two migration phases with zero production incidents.
Stability first. Innovation when you're ready.
Legacy Mainframe environments carry decades of critical business logic. Replacing them isn't always the right first move, and while the long-term roadmap takes shape, your production environment can't afford instability.
GBT provides structured, SLA-backed managed support for Mainframe applications from incident resolution and batch monitoring through to change management and performance tuning. Our support teams have worked inside large enterprise environments. We know legacy systems from the inside.
GBT's team carries experience from Mindtree and other large-scale enterprise delivery organisations — the firms that originally implemented, maintained, and modernised Mainframe environments at enterprise scale. That background isn't a credential. It's why our assessments find what others miss.
Every migration programme GBT manages has a documented rollback strategy at every phase. Because the businesses that get into trouble are the ones that assumed they wouldn't need one.
Defined migration or modernisation with clear scope
See details ↓Evolving requirements or exploratory programmes
See details ↓Ongoing AMS with consistent team and SLA
See details ↓Cost-optimised delivery with onshore governance
See details ↓A 30-minute assessment call is enough to determine whether you need support, migration, or modernisation, and what a realistic programme looks like for your specific environment.
Book a Free Assessment CallWe'll tell you honestly if your situation is outside our scope. We'd rather do that in 30 minutes than three months in.