Legacy modernization

Leave it running.
Make the next change.

Kelumen helps companies change legacy systems that still run the business. We read the code, pin down its behavior, then split and rewrite along real boundaries. AI speeds up reading, drafting, and comparison. An engineer reviews every change that reaches the main branch.

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Team: 100 people
Subject: Legacy code still in production
Method: AI-assisted, engineer-owned

Pin the behavior first

No comparison, no replacement. Record inputs, outputs, and side effects on the paths that matter.

One boundary at a time

Change one module, batch job, or interface, and keep a way back.

A draft is not a commit

The model may draft. The person who reads the diff, runs the comparison, and commits owns the change.

What we take on

All services

Legacy assessment

Map the language, build, writes, and release path, and mark where work can start.
Splitting and refactoring

Separate tangled responsibilities while the system keeps running.
Migration

Move off a language, framework, or runtime that can no longer be maintained, without changing behavior.
Tests and handover

Add the regressions that matter, and leave a record someone else can run.

A model can write quickly.
Someone still has to read it.

This is how Kelumen works. AI widens coverage. It does not replace judgment, or the decision to ship.

If the system cannot stop, start with one path.

Tell us the language, the scale, and the business path that is hardest to change.

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Leave it running.Make the next change.

Engineering rules

Pin the behavior first

One boundary at a time

A draft is not a commit

What we take on

Legacy assessment

Splitting and refactoring

Migration

Tests and handover

A model can write quickly.Someone still has to read it.

If the system cannot stop, start with one path.

Leave it running.
Make the next change.

A model can write quickly.
Someone still has to read it.