A mainframe hall: rows of tape and disk cabinets, operators working at a shared console.

Modernise mission-critical software, safely.

Streamline the modernisation process. Enhance control, visibility and verification. Reduce risk and cost in complex migrations.

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Streamlining modernisation in practice

A network rack: patch panels and managed switches, with ranks of teal ethernet cables looped between them.
Technical case
Perl to Rust migration

Modernisation becomes safer and faster when every slice has an explicit scope, rollbacks and evidence.
An Amsterdam canal at sunset, tour boats moored along the quay in front of the Munttoren.
Customer case
Frontend modernisation

Tackling a frontend migration 15 years past due in bite-size pieces.
Someone in a suit reading the business pages of a newspaper, market tables in view.
Customer case
Legacy PHP upgrades

Maintenance can continue without making senior engineers responsible for every repetitive detail again.
Explore the features of the platform
// legacy modernisation

Migrations are risky and costly.

Every company must keep systems secure, current, and compliant. Software platforms are aging out, and extended security contracts further pile on to maintenance costs. High risk projects require strict and slow management.

Bosun mitigates risk and increases velocity.

Streamline the modernisation process
Every production behavior is inventoried up front and ordered by dependency. Missing building blocks become their own slices, before the first behavior that needs them.
Enhance control, visibility and verification
One test across two implementations. Equal results are the default, and only explicitly declared differences are allowed.
Reduce risk and cost in complex migrations
A router chooses per action which way it goes. Every migrated behavior rolls back on its own, and what has not been migrated keeps running untouched on the existing system.

Modernising critical software infrastructure.

Bosun analyses your codebase, assesses your migration path and architectural options. Your engineers approve the migration path and work items. The Bosun process is structured, repeatable and AI-supported, with accurate, comprehensible and traceable evidence, on-premise and with sovereign AI models.

  1. Assess Find the seam
  2. Strategize Choose both architectures
  3. Map patterns Make translation consistent
  4. Bootstrap Prepare coexistence and rollback
  5. Choose slices Pick the next small behavior
  6. Migrate one slice Prove, route, and observe
Learn more about modernisation with Bosun
// from the blog
All posts
12 AUG 2026

Evaluating Open Weight Models for Software Maintenance

Can open weight models automate software maintenance effectively and at lower cost?

Read the post
4 AUG 2026

Introducing Parity: Prove what a replacement preserves

Replace legacy software without losing the behavior your team depends on.

Read the post

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Start with a proof of value.

One modernisation solution with demonstrable value. Bosun engineers work with your engineers to connect Bosun safely to your environment and set up the migration process.

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You bring access to the codebase, impactful cases and reviewers. Bosun brings installation, workflow, guidance and measurement.
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