PropCheck — AI Property Trust Score for India

Problem

Indian property buyers lose lakhs to fraudulent listings on Magicbricks, 99acres, Housing.com, and NoBroker. Fake RERA numbers, recycled stock photos, and inflated pricing slip past buyers because no neutral tool exists to verify a listing in seconds.

Business Impact

Housing.com's own survey says 65% of buyers can't trust listings. Banks and NBFCs spend ₹2,000–5,000 and 3–7 days on property due-diligence per home loan file. PropCheck closes both gaps with one neutral AI engine — free for buyers, API-priced for lenders.

System Approach

• Next.js 14 App Router frontend with Tailwind for the consumer landing, /how-it-works, and /for-lenders pages
• FastAPI 0.115 + Pydantic 2.9 backend exposing /v1/check, /v1/feedback, /healthz endpoints — OpenAPI auto-generated at /docs
• PostgreSQL 16 + SQLAlchemy 2 + Alembic migrations for listing checks, feedback, and the locality price index
• httpx + BeautifulSoup4 + lxml scrape pipeline with Gemma 4 31B (OpenRouter free) as LLM parsing fallback when sites are SPA or rate-limited
• imagehash + Pillow for perceptual-hash reverse-search against a known stock-photo and recycled-listing dataset
• slowapi for IP-level rate limiting; structlog for structured request logs
• Chrome MV3 extension surfaces the Trust Score directly on Magicbricks/99acres/Housing/NoBroker product pages
• Vercel hosts both the Next.js frontend (propcheck.rohitraj.tech) and the FastAPI backend (api.rohitraj.tech) as serverless

Key Decisions & Trade-offs

• Free forever for buyers, paid API for lenders — neutrality is the moat; if we monetized buyers we'd be just another portal
• LLM parsing fallback over heavier headless scrapers — Gemma 4 31B on OpenRouter free tier kept the bundle and the bill at zero
• 8 explicit signals over a black-box ML score — Indian buyers and lenders both want explainable red flags they can act on
• Karnataka RERA first (Bangalore launch May 2026), expand state-by-state — RERA APIs and formats differ per state
• Chrome extension as a wedge — buyers already browse listings on the portals; meet them on the page they're already on

Current Status

Live in production at https://propcheck.rohitraj.tech/. FastAPI backend live at https://api.rohitraj.tech/ with /v1/check + /v1/feedback shipping. LLM parsing fallback verified live (Gemma 4 31B). Chrome MV3 extension built (phase 8). Day 14 calibration on real Magicbricks/99acres URLs revealed SPA + rate-limit walls — calibration deltas in active tuning.

Roadmap

• Tune calibration deltas on real-world URLs from day-14 report
• Harden scraper for SPA + rate-limit walls (Browserbase / residential proxy fallback)
• Expand RERA coverage from Karnataka to Maharashtra, Telangana, and Tamil Nadu
• Ship Chrome extension to the Web Store after MV3 review
• Onboard first lender to the /v1/check API for home-loan diligence

What I'd Improve Next

• Could add a community-sourced scam-listing reporting flow with signed feedback
• Consider WhatsApp delivery of Trust Scores for users who paste links there (currently parked per commit 553c334)

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