Case studies

How the work actually went

Long-form write-ups of real engagements: what was wrong, how it was measured, what was tried and rejected, and what could not break while it changed. Each one states where its numbers come from and what has been left out.

  • Biotech · Data platform

    The API didn't look slow. It looked broken.

    A scientific data API failing as timeouts and 5xx rather than slowness. Five independent problems across schema, query planning, transport and server concurrency, each producing the same symptom.

    ~70% faster end to end

    Figures from measurements committed to the client's repository. Client and partner anonymised.

  • Integrations · Open source

    The contract fit databases. The market wanted SaaS APIs.

    An integration contract designed for CRUD-over-a-table, met with accounting and commerce APIs. ~125 vendor actions covered by one reflective dispatcher, and test suites brought to a catalog that shipped without them.

    125 vendor actions, one dispatcher

    Public MIT-licensed repository. Every figure is a file-level count or a dated commit.

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Houssem Eddine Zerrad

Staff Software Engineer & Cloud Architect · © 2026