LeaseGuard
About LeaseGuard

Built so you can read what you sign

Most Ontario tenants sign a lease without fully understanding it. Many leases contain clauses that are void under the Residential Tenancies Act — but tenants rarely know this until a dispute arises. By then, the leverage is gone.

LeaseGuard reads every clause against real statute text and tells you exactly what you are agreeing to — before you sign.

Design principles

Retrieval, not assertion

LeaseGuard never cites a statute from AI training memory. Every legal claim is backed by a statute section retrieved at runtime from a corpus of 2,372 RTA chunks, indexed in Supabase pgvector. If no relevant section can be retrieved, no claim is made.

Unenforceable, not illegal

Under Ontario’s RTA, problematic clauses are almost always void and unenforceable — the landlord has not committed a criminal offense. LeaseGuard always uses the correct language: “potentially unenforceable” rather than “illegal”, unless a specific offense provision applies.

Deterministic scoring

Risk scores are produced by a TypeScript rule engine — not an LLM judgment call. Patterns are matched, statutory violations are checked programmatically, and scores follow a consistent algorithm. The same clause always receives the same score.

Ontario-only, by design

LeaseGuard uses the Ontario Residential Tenancies Act, 2006 and LTB case law exclusively. Analyzing leases from other provinces with Ontario law would be actively misleading. Uploads that are not Ontario residential leases are rejected with a clear explanation.

How it is built

The full stack, for those who want to know.

AgentClaude (Anthropic) — MCP tool orchestrator
EmbeddingsGemini gemini-embedding-001 — 768 dimensions
Vector DBSupabase pgvector — hybrid BM25 + vector search
PDF parsingPyMuPDF + Tesseract OCR
FrontendNext.js on Vercel
Corpus2,372 RTA chunks — granular subsection level
Limitations to be aware of
  • LeaseGuard only covers Ontario residential leases — commercial, agricultural, and non-Ontario leases are not supported.
  • Analysis quality depends on text extraction quality. Poorly scanned PDFs may produce lower-confidence results.
  • The LTB decisions corpus is currently limited. Tribunal citation quality will improve as the corpus grows.
  • LeaseGuard is an educational tool, not a substitute for legal advice. For specific disputes, consult a licensed paralegal or lawyer.
Legal disclaimer

LeaseGuard provides educational information only and does not constitute legal advice. Every legal claim in a LeaseGuard report is grounded in retrieved statute text and is provided for informational purposes. For matters requiring professional legal judgment — such as disputes with a landlord, LTB applications, or negotiating lease terms — consult a licensed paralegal or lawyer. Community Legal Clinics in Ontario offer free tenant legal help to those who qualify.

Questions, feedback, or a lease you think LeaseGuard got wrong?

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