SLED Subcontracting
SERVICE 06 · SYSTEM MODERNIZATION

Modernize in place, without going offline

Legacy and modern run side by side, outputs compared, then cut over one increment at a time.

Let's talk See what we build
  • Strangler-fig pattern
  • Zero-downtime cutover
  • Reversible at every step

What we built

Four things every modernization ships with

Mapping, parallel running, mirrored verification, and incremental cutover. Each step is proven before the next one starts, and every one can be rolled back.

01

Dependency mapping

Automated scanners map undocumented logic, data flows, and integrations before any refactoring begins.

Proof layer You get a dependency map and architecture assessment a procurement or security review can read.

02

Parallel running

A modern environment runs beside the legacy core so daily operations never stop.

Proof layer The legacy system stays the system of record until the modern path clears its parity threshold.

03

Mirrored verification

The same traffic flows through both systems and every output is compared programmatically for parity.

Proof layer Nothing cuts over until the diff report is clean on real production traffic, not test fixtures.

04

Incremental cutover

We modernize component by component, never in one risky rewrite.

Proof layer Each increment has a written rollback path, so any step can be reversed inside a maintenance window.

Named stack
Java .NET COBOL DB2 Oracle PostgreSQL MySQL Kubernetes Docker AWS Azure Node.js TypeScript REST APIs GraphQL Microservices
parallel environments keep operations running through cutover
0 downtime
run the same traffic side by side until outputs match
2 systems
every increment has a written rollback path before it ships
100% reversible
still run software over 20 years old (McKinsey). We retire it piece by piece.
70% of Fortune 500

Use cases

Systems we modernize most often

If it is critical, undocumented, and nobody wants to be the one who touches it, it is a candidate. These are the shapes we see most.

  • Monolith to services

    Wraps the monolith in modern APIs, then peels off one bounded domain at a time while the monolith keeps serving the rest.

    SaaS · Retail · Logistics

  • Database migration

    Moves DB2, Oracle, or SQL Server workloads to PostgreSQL or managed cloud with dual writes and row-level reconciliation.

    Finance · Healthcare · Public sector

  • COBOL and mainframe wrapping

    Exposes mainframe transactions through a modern API layer so new products ship without touching the core until it is ready.

    State & county · Insurance · Banking

  • On-prem to cloud

    Containerizes workloads, replaces hand-managed servers with Kubernetes, and cuts over environment by environment.

    Manufacturing · Education · Nonprofits

  • Spreadsheet and tool consolidation

    Replaces spreadsheets and disconnected admin tools with one role-based internal system that owns the data.

    E-commerce · Operations · Field service

  • Integration layer rebuild

    Replaces brittle point-to-point scripts and nightly batch jobs with event-driven integrations you can observe.

    ERP · CRM · 3PL

  • Performance optimization

    Profiles the slow paths, fixes queries, caching, and hot loops, and proves the gain against the original baseline.

    High-traffic apps · Portals · Reporting

  • Compliance-driven upgrades

    Moves off unsupported frameworks and runtimes with a documented change log an auditor or prime can review.

    Healthcare · Government · Regulated SaaS

Client stories

Legacy retired, operations never paused

Each one replaced something fragile that a team depended on every day. Each one went live without a stop-the-world rewrite.

All case studies

How we ship

Built to be verified, reversed, and owned

Every modernization leaves with the same four things defined in the plan before a line of legacy code is touched.

01 Verification

A passing test suite proves it once

Production requires proving it on real traffic, every day, until cutover.

Mirrored traffic
The same requests flow through legacy and modern in parallel. Outputs are diffed programmatically, and every mismatch is triaged before the increment can move.
Parity threshold
Written into the plan before the build starts. If the modern path does not clear it, it does not cut over.
Data reconciliation
Row counts, checksums, and business totals are reconciled between old and new stores on a schedule, not once at the end.
02 When it breaks

Every increment has a way back

We assume something will surprise us and plan the reverse path first.

Rollback per increment
Each cutover ships with a written, rehearsed rollback that fits inside your maintenance window.
Feature flags
Routing between legacy and modern is a flag, not a deploy, so switching back takes minutes.
Legacy stays live
The old system is not decommissioned until the modern path has run clean for an agreed period.
03 Governance

Documentation a review can read

Modernization changes the system everyone depends on, so the record has to be readable by non-engineers.

Dependency map
Automated scanners map logic, data flows, and integrations before refactoring, and the map is kept current as work lands.
Change log
Every increment logs what moved, what was verified, and who approved the cutover, in a format a security or procurement review accepts.
Access boundaries
We work behind your access controls and, for SLED scope, behind the prime under NDA.
04 Run cost

Two systems cost more until one retires

Parallel running is temporary by design, and the plan says when it ends.

Retirement date
Each legacy component has a target decommission date tied to its parity milestone, not an open-ended "later".
Infra baseline
Hosting, licensing, and maintenance costs are measured before the work starts so the saving is a number, not a feeling.
No hidden dual-run
Duplicate infrastructure is tracked and shut off as increments retire, so the bill goes down as the project progresses.

WHO RUNS IT AFTER CUTOVER

Operate retainer We monitor the modern platform, run scheduled reconciliations, and respond within an agreed window.
Handover Your team runs it. You get the dependency map, runbooks, architecture docs, and 2 training sessions. We stay reachable for 30 days.

WHAT WE WILL NOT BUILD

  • A big-bang rewrite with a single cutover weekend. The risk is the rewrite, and we remove it.
  • A migration without mirrored verification. If we cannot compare outputs, we will not cut over.
  • Modernization of a system we are not permitted to read end to end.
  • A new platform that recreates the undocumented logic without documenting it.
  • Anything where a supported upgrade path or existing product solves it. We will tell you which one.
For U.S. SLED prime contractors

State and county modernization, behind the prime.

For SLED scope under NAICS 541512, we untangle mainframe and legacy technical debt as your subcontractor, working behind the prime, never facing the agency.

NAICS 541512 541511 541519
See SLED Subcontracting

NDA-first, subcontract-only. We work behind the prime, under your brand. We do not pursue prime contracts and we never face the agency.

Verified and reversible. Mirrored traffic proves parity before cutover, and every increment can be rolled back.

Built for security review. Architecture assessments, dependency maps, and zero-downtime strategies a procurement review can read.

FAQ

Modernization, answered.

Straight answers about retiring legacy without the rewrite risk. If yours isn't here, ask it on the call, we answer the hard ones first.

Ask the hard one

Will our daily operations go offline during the transition?

No. We use parallel running environments to ensure zero downtime during the cutover process.

How do you handle severely undocumented legacy code?

We use automated dependency scanners to map the logic and architecture before any refactoring begins.

Do we have to replace the entire system at once?

We strongly advise against a full rewrite. We modernize incrementally, component by component.

How do you ensure the new system calculates exactly like the old one?

We run mirrored traffic through both systems simultaneously and compare the outputs programmatically to ensure perfect parity.

It is not broken, so why touch it?

A fair instinct. The danger is doing it under pressure later. We de-risk it with parallel environments and incremental, mathematically verified, fully reversible cutovers.

Related work

Service Data and platform → Service Custom software development → Service Strategic enablement & change management → Industry Education →

Start the conversation

Retirethelegacysystem
without the risk

Tell us which old system everyone is afraid to touch. That is where we start mapping.

Scope a modernization
30 minutes the engineer who leads delivery no deck, no pitch