Sovereign · Legacy system modernisation

Modernise your oldest systems. Prove they still work the same.

Sovereign reads your old software, rebuilds it in modern code, and proves the new system gives exactly the same results before you switch over.

No AI
Runs inside your network
You approve every step

Get in touchSee Sovereign More from Syntaxe

Sovereign

Legacy modernisation

Sovereign reads your old system, rebuilds it in modern code, proves the results match, and switches you over in steps.

Runs inside your network. No AI. You approve every step.

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Sovereign

01 Read
02 Rebuild
03 Prove
04 Switch over

The situation

Most organisations still run on software written decades ago.

People

Fewer people understand it every year.

The engineers who built it have moved on. The documentation stopped matching the code long ago. Nobody can say for sure what a change will break.

Attackers

Old systems are easy targets for attackers.

Old systems are hard to secure: no patches, no vendor support, no clear map of what connects to what. Attackers look for systems like these.

Cost

They cost more to run every year.

Old systems need rare skills and expensive support contracts, and the number of people and suppliers who can maintain them keeps shrinking.

Sovereign rebuilds the systems you cannot patch. It proves the new system gives exactly the same results as the old one, so your team can switch over knowing nothing has changed.

See how it works

How Sovereign works

From a system nobody understands to one your team owns.

01
Read
Sovereign reads every program and lists the rules your business runs on, each one traced to the file and line it comes from.
02
Rebuild
It rebuilds the system in modern code from what it read, with a modern web front end.
03
Prove
Old and new run on the same inputs. You see every match and every difference until the report is clean.
04
Switch over
Proven parts take over in steps, 25%, 50%, 75%, then 100%, with the old system kept ready and an automatic switch back if results drift.

Built for an enterprise

No AI. Nothing is sent to an AI model, and the results are exact and repeatable.
No internet needed. It runs on your own hardware, including air-gapped sites. Your code never leaves the building.
Every decision recorded. Who approved what, and when, is kept for your auditors.
Proof you can re-run. Each proof comes with evidence your own team can run again, without us.

Proven language by language

Each language is checked against its own compiler or interpreter.

COBOL
PL/I
JCL
Fortran
MUMPS
REXX
Perl
ColdFusion

Latest articleThat 844-year COBOL calculation? Sovereign beats it.Read

The first step

Start with an Assessment.

Sovereign maps your system before anything changes: every program, what it depends on, where the risk is and where to start. The scope is agreed in writing before we begin, and you decide afterwards whether to go on.

Get in touch See Sovereign in full

Security and engineering, from the team behind Sovereign.

Secure the systems and AI agents around it.

Kern stops AI agents reaching data they should not. Anneal finds the weaknesses an attacker could actually use, so you fix those first.

See Kern and Anneal

Build what comes next.

Our engineers build new tools and products, cloud systems, and AI agents for the software you already use. You own everything we build.

See our engineering

Our other products

Security for the systems you keep, and the AI agents you add.

AI agent security

Kern

For security teams deciding whether to allow an AI agent

Kern shows everything an AI agent can reach, and blocks it if it tries to send your data somewhere it should not go.

You know this before the agent goes live.

1See what it can reach
2Prove where data can go
3Block calls you have not allowed

See Kern

Vulnerability management

Anneal

For security teams with more alerts than time

Security scans find thousands of weaknesses. Anneal shows the few an attacker could actually use, and checks each fix worked.

You fix the ones that matter first, and you can show the proof.

1Find the real ways in
2Fix those first
3Check each fix worked

See Anneal

Engineering

Software built for your organisation.

We build new tools and products, cloud systems, and AI agents for the software you already use. Each piece of work is agreed in writing before it starts, and you own everything we build.

Get in touch All engineering services

Cloud
We design your cloud setup, move your systems onto it, and show you it works as agreed.
AI integration and AI agents
We build custom AI agents and AI features for your organisation. For example: an agent that carries out a routine task for your team, an assistant that answers questions from your own documents, or a tool that reads and sorts incoming paperwork. We connect them securely to the software and data you already use.
Custom builds
Platforms, internal tools and products, built with documentation your own team can maintain.