The migration playbook 802.software uses to move legacy VB.NET, COBOL, and PHP3 platforms onto modern stacks without downtime, lost data, or vendor lock-in.
Modernizing older software without stopping the business
Moving an ageing system onto a maintained stack without stopping the business that depends on it, one piece at a time.
Our approach
Rewriting a working system from scratch is the riskiest way to modernize it. The old system keeps changing while the new one is built, the cut-over day becomes a cliff, and the business pays twice. We replace older software in slices instead, with both versions running until each new piece has proven itself.
The approach is often called a strangler-fig migration: new code takes over one route, report or workflow at a time, traffic moves across gradually, and the old system shrinks until it can be switched off.
What is included
- System review
- A written assessment of the current system: what it does, where the risk is and what to move first.
- Migration plan
- An order of work that moves the riskiest or most expensive parts first and keeps every step reversible.
- Data migration
- Moving records to a modern database with checks that every row arrived intact.
- Side-by-side running
- Old and new versions running together, with traffic moved across one piece at a time.
- Hosting move
- From a single ageing server to managed hosting with backups, monitoring and repeatable deploys.
- Retirement
- Switching the old system off once nothing depends on it, and archiving what must be kept.
Who it is for
- Businesses running on software whose original developers have moved on.
- Systems that only one person can deploy, or that run on hardware nobody wants to touch.
- Teams that need new features the current platform cannot support.
How the work runs
Built with TypeScript, Node.js, PostgreSQL, Change data capture and Managed hosting.
01
Assess
Read the code and the data, talk to the people who use it, and write down the risks.
02
Plan
Agree the order of the migration and what success looks like for each slice.
03
Migrate in slices
Move one piece at a time with both systems running, and check each step before the next.
04
Retire and maintain
Switch the old system off and look after the new one.
Questions
Do we have to stop using the old system during the migration?
No. Both systems run side by side, and work moves across one piece at a time, so the business keeps operating throughout.
What if nobody understands the old code any more?
That is common. The first step is a written review of what the system actually does, based on its code, its data and the people who use it.
Can you modernize just one part?
Yes. Often the right first step is to move the single most fragile part, such as reporting or a customer-facing form, and leave the rest for later.
How do you avoid losing data?
Every data move is checked against the source before traffic switches over, and each step can be reversed until it is proven.
Read next
- Strangler-fig migrations without losing a transaction
- How we architect platforms for a five-year horizon
The architecture decisions that decide whether a platform still works, untouched, three years after launch, and how a Vermont studio makes them early.
Other services: Web applications and SaaS, Mobile apps for iPhone and Android, Internal tools and business systems
Tell us what you are building.
A few lines about the project and when it needs to ship is enough to start.