COBOL runs the world. We help it run on something else.
Roughly 40% of banking systems still run on COBOL. The engineers who built them are retiring. The batch windows are shrinking. The audit requirements are growing. Parity rebuilds financial legacy systems with provable parity — bit-level test coverage, shadow-traffic replay, zero-downtime cutover, and a regulatory audit trail built into every change.
The last generation of COBOL engineers is retiring. Most banks can't hire replacements at any price — and every line of undocumented JCL becomes an operational risk the moment its author walks out the door.
02
The batch window is closing
Twenty-four-hour trading, real-time settlement, and global operations have killed the overnight batch. Systems designed for 6-hour processing windows now run in 45-minute slivers — and one bad deploy blows the window for the whole day.
03
Compliance is immovable
SOX, PCI-DSS, NIST, GLBA, OSFI — every migration has to preserve the audit trail, the approval history, and the data lineage. Most modernization projects stall here: the auditors won't sign off on a system they can't replay.
04
Integration debt compounds
The core is surrounded by thirty years of adapters, ESB pipelines, message queues, and screen scrapers. Touch the core and the perimeter breaks. Touch the perimeter and the core becomes unreachable. Most teams freeze.
§2The Parity approach
Rebuild with parity — then decommission with confidence.
Financial systems can’t be rebuilt on vibes. The validation framework matters more here than anywhere else we work: nothing ships to production until the new system behaves identically to the legacy one, under real traffic, across millions of transactions.
01
Shadow-traffic replay
Every piece of the new system runs side-by-side with the legacy for weeks. Real production traffic is mirrored to both. We compare outputs byte-for-byte and escalate every divergence before the old system is decommissioned.
02
Bit-level parity test suite
For financial systems, "close enough" isn't. Our parity suite verifies arithmetic results, rounding behavior, timezone handling, and transaction ordering match legacy exactly — across millions of synthetic and replayed transactions.
03
Regulatory audit trail — by default
Every code change, every spec update, every validator run is logged to an immutable audit stream. When your auditors ask "why did this calculation change on March 14," we replay the answer in under a minute.
04
Zero-downtime strangler cutover
Feature by feature, traffic is shifted from legacy to new. Each shift is reversible in seconds. The legacy system stays live until parity hits 99.999% — and only then does the lights-out decommission begin.
A Parity Audit for a financial legacy system runs three weeks and produces a migration plan, a parity test strategy, and a concrete decommission path. Ready when you are.