Hasan Yahşi

Repair bench, field operations, and since 2022 a hospital network that has to work at three in the morning. The software I write comes out of that work.

Experience

1. Systems administrator2022 – present

   Özel Çankaya Tıp Merkezi & Karataş Hastanesi, İzmir

   • Windows Server, Active Directory and VMware estate for a hospital and a medical centre
   • Network, firewall and endpoint operations; on-call for outages
   • Integrations around the hospital information system (HBYS) and its vendors
   • First-line to third-line user support for clinical and administrative staff
2. Technical field manager2018 – 2022

   Turkcell

   • Planning and running installation and fault teams in the field
   • Escalation point between customers, technicians and the operator
3. IT support and technical service2016 – 2018

   Karhan Hukuk

   • Hardware diagnosis and repair; the habit of measuring before replacing started here
4. Independent software workSince 2025

   DijitalOfisim, İzmir

   • Static sites and single-page microsites for two physicians and a small studio, with Google Business and schema markup
   • WhatsApp assistant and n8n automation flows prepared as a service; no paying client yet
   • paintcheck, the open-source contrast tool described on this site

Projects

• paintcheck: open-source contrast checker that measures rendered pixels instead of CSS; MIT, on GitHub with CI, 2026.
• hasanyahsi.com: this site; Next.js 16 static export on Firebase Hosting, measured with its own tooling, 2026.
• DijitalOfisim: websites for small businesses in İzmir, since 2025.

How I work

• Measure before claiming. If there is no number, I say I do not know.
• Small and shippable. A plan is a list of things that can be shown within a week.
• Write the failures down. The paintcheck changelog lists the measurement bugs before the features.