Kira Cetveli
A serverless tool that runs entirely in the browser, built to calculate rent increases correctly and bring everyday rental tasks (late interest, deposits, tax estimates, documents, contract calendar) into one place.
Problem, approach, evidence.
Problem
The rent increase rate is recalculated every year and depends on TBK article 344 and CPI data. Late interest, deposits and tax each need their own tools and documents. One wrong number means real money lost.
Approach
The calculations are pure functions independent of the UI and are protected by unit tests. None of the legal values is hard-coded; they come from validated data files. Every result screen and document shows the not-legal-advice notice and the data's last update date.
Evidence
Measured live: Lighthouse 98 on desktop, 78 on mobile; LCP 0.9 s on desktop, 3.9 s on mobile; layout shift 0; accessibility 100. Unit (Vitest) and end-to-end (Playwright) tests are in place.
From calculations to documents.
Rent increase (the 12-month average CPI for the renewal month is filled in automatically), late interest, back-period difference, deposit refund, withholding and income tax estimate.
Rent increase notice, eviction notice and deposit refund request, as a PDF or editable text.
A contract calendar (.ics), optional reminders kept only on this device, and a contract checklist.
Tenant rights, landlord obligations and frequently asked questions, delivered as a PWA that works offline.
Data lives apart from code.
↑ The monthly data update arrives as an automatically opened pull request; it does not ship until validation passes.
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