Modernize your legacy system without stopping operations
We migrate monoliths and old systems to modern, maintainable architectures incrementally — with the strangler fig pattern, not a big-bang that shuts down your business over a weekend. The code is 100% yours from the first commit.
Legacy modernization means rewriting and migrating an old system (FoxPro, VB6, .NET Framework, Delphi, an undocumented monolith) to a current architecture without stopping your operation.
We do it module by module with the strangler fig pattern: we build the modern version of each piece, redirect traffic gradually, and shut the old one down only when the new one is 100% stable in production. No black box, no blind full rewrite, and a system that is always running.
Why iTechDev
Fixed budget
Scope and price defined before we start. No hourly billing, no ambiguous scope.
Code 100% yours
All code and configuration are your property from the first commit. No vendor lock-in.
Progress every 2 weeks
Live functional demos each sprint. You see real progress, not a months-long black box.
Engineering with process
CMMI Level 2, 5.0★ on Clutch and 200+ projects. Nearshore team in Monterrey + Texas, in your time zone (CST).
When you need it
What it includes
Technical audit (discovery)
Full functional inventory, integration map, static code analysis and data assessment. We document the business rules and hidden workarounds nobody remembers, even when there is no prior documentation.
Migration strategy
We choose strangler fig, parallel run or big-bang based on your system's criticality, budget and risk tolerance — and we explain why, with a phased plan and a target architecture.
Incremental refactor
We migrate module by module to a maintainable architecture. The old and new systems coexist through bridge APIs while traffic is redirected gradually. With minimal downtime.
Regression tests
A test suite that validates each new module produces the same results as the old one before shutting it down. Unit, integration and acceptance tests with our internal ARIA platform.
Data migration and cleanup
We do not just move data: we clean up duplicates, inconsistencies and orphan records accumulated over the years, with transformation rules validated by the business.
Coexistence & bridge APIs
We build the layer that lets old and new coexist: bridge APIs, an anti-corruption layer that isolates the new system from the legacy's messy model, and the routing that redirects traffic module by module without the user noticing.
Documentation + CI/CD
Architecture, data model, runbook and ADRs. Continuous integration and deployment pipelines, configured environments and a tested rollback plan for every phase. All 100% yours.
Training & handover
Handover sessions with your team, operations documentation and 90 days of support, so knowledge of the new system lives in your organization and not in "the only person who knows it" — exactly the problem we came to solve.
How we work
01 · Technical discovery
We audit the legacy system: functional inventory, integrations, data and technical debt. Deliverable: a recommended strategy (strangler fig / parallel run / big-bang), a target architecture and a phased timeline estimate.
02 · Foundations
We set up the infrastructure (Azure or AWS), CI/CD pipelines and development, staging and production environments. Deliverable: infrastructure as code, operational pipelines and the base architecture of the new system.
03 · Incremental migration
We build and release module by module with strangler fig, with regression tests validating parity before turning off the old one. Deliverable: each module in production, validated for 2-4 weeks with real users, with its tests green.
04 · Data migration
We move and clean the data in phases: deduplication, inconsistency fixes and transformation rules validated by the business, with reconciliation against the source. Deliverable: migrated and reconciled data, with a quality report.
05 · Go-live and stabilization
Controlled deployment, intensive support during the first weeks, active monitoring and fine-tuning. Deliverable: the new system stable in production, the old one turned off, a runbook and a tested rollback plan — and code 100% yours.
Tech stack
The tools and platforms we build it with — chosen for your problem, not for hype.
Frequently asked questions
Is there a risk of breaking production during the migration?
With strangler fig the risk is low and controlled: the old system is never turned off until the new one is 100% stable in production. If a new module fails, we redirect traffic back to the old one in minutes. On top of that, every phase has a tested, documented rollback plan. Operations never stop.
How long does it take to modernize a legacy system?
It depends on size and strategy. For a medium system (5-10 modules), the typical range is 6-18 months; an enterprise system may take longer. The key point is that with strangler fig you start seeing value from month 3-4 — you don't wait until the end for something to work. We give you a detailed timeline after discovery.
Big-bang or incremental migration?
In most cases we recommend incremental migration (strangler fig): safer, no downtime and value delivered in stages. Big-bang (turning off the old system and switching on the new one at once) only makes sense for small systems, with few users, or when the legacy is so unstable that keeping it during a gradual migration is riskier. We tell you which one applies to your case, with no agenda.
What if we have no documentation of the old system?
It's the most common situation and it's not a blocker. We rebuild the knowledge through reverse engineering: static code analysis, database analysis to understand the data model, user interviews and log analysis to discover how the system is really used. We budget additional discovery weeks when needed.
Do you rewrite everything, or can you keep parts that work?
We don't rewrite for the sake of it. During discovery we assess each module: what works and is maintainable is kept or wrapped in an API; what is critical technical debt or unsupported technology gets rewritten. Sometimes the best call is to modernize half the system and leave the other half as is. We give you that recommendation with reasons, not a total-demolition order.
How much does it cost and how do you bill?
We work with a fixed budget defined after discovery — no hourly billing and no ambiguous scope. The cost depends on the system size, the number of modules and integrations, and the chosen strategy. With strangler fig you can spread the investment across phases, so each delivered module is already productive even if you adjust the pace. The code and documentation are 100% yours from the first commit.
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