Meeting old systems where they are
Legacy systems are often load-bearing: they run the business and can't just be replaced. The realistic move is to build a bridge from the old world to the new, so modern apps can read and write to it safely without a risky rewrite.
- On-prem databases (SQL Server, Oracle, DB2, and older engines)
- Mainframe and AS/400 systems via their available interfaces
- SOAP web services, fixed-width files, and EDI feeds
- Desktop and client-server apps with no real API
- Systems reachable only inside a private network
How we bridge the gap
When there's no clean API, we build one. Often that means a modern API wrapper in front of the legacy system, a scheduled sync, or a secure gateway that lets cloud services reach an on-prem box without exposing it to the internet.
- An API layer wrapped around the legacy system's real interface
- Database-level integration where no API exists at all
- File-based exchange (CSV, XML, EDI) on a schedule
- Secure tunnels or VPN so cloud apps reach on-prem systems safely
- Change-data-capture to detect updates in systems that can't push events
- A translation layer converting old formats to modern JSON
Doing it without breaking production
The number-one rule with legacy integration is do no harm — these systems are often fragile and undocumented. We work read-only first, test against copies, and add monitoring so we understand the system's real behavior before we ever write to it.
- Read-only first, writes only once behavior is fully understood
- Testing against a copy or staging instance, not the live system
- Rate limiting so we don't overload an old, resource-constrained box
- Careful handling of undocumented quirks and edge cases
- Monitoring and rollback plans before any change goes live
- A path toward gradual modernization if and when you want it
More on apis & integrations
Frequently asked questions
Our old system has no API at all — can you still connect it?
Usually, yes. If there's no API, we integrate at the database level, through file exchange, or by putting a modern API wrapper in front of it. It takes more discovery to map how the system really behaves, but a total lack of API rarely blocks integration.
Will connecting to it risk breaking the legacy system?
We treat that as the top risk. We start read-only, test against a copy where possible, rate-limit our access so we don't overload it, and add monitoring. We don't write to a production legacy system until we understand exactly how it responds.
It's on-prem and everything else is cloud — is that a problem?
No, that's a common setup. We use secure tunnels or a gateway so cloud services can reach the on-prem system without exposing it to the open internet. The connection stays private and controlled.