All Startup Ideas

Landlord Tenant Risk Screener

Forensic tenant screening for small landlords: upload applications, flag fake docs and risk signals, get a plain-language score before you sign the lease.

A first-time landlord calls the employer listed on the rental application. Friendly voice. Confirms title, start date, salary. He offers the lease that weekend. Eight months later, during the eviction, his lawyer traces the number. Burner phone. Same number on four other applications across two states. The pay stubs were a patched PDF: mismatched fonts, round-number net pay, metadata that said the file was authored the night before the showing. None of that was in the TransUnion packet he paid forty dollars for. The bureau told him the credit score. It did not tell him the story was fake.

Built for Small Business Owners, Solo Founders, Weekend Builders, Non-Technical.

The global tenant screening services market is valued at $1.85B in 2025, $1.94B in 2026, and $2.83B by 2034 at a 4.97% CAGR (Business Research Insights). Alternate cuts: $3.28B in 2023 to $5.37B by 2030 at 7.3% CAGR (Verified Market Research); $1.5B in 2023 to $2.7B by 2031 at 9.3% CAGR (Precision Business Insights). Pick one series for decks; the direction is the same.

Suggested stack: Next.js (App Router) + Vercel, Convex, Claude (Sonnet) with a vision/docs fallback, PDF parse + metadata, Public records adapters, Stripe Billing. Weekend scope: about 10 hours.

The Problem

A first-time landlord calls the employer listed on the rental application. Friendly voice. Confirms title, start date, salary. He offers the lease that weekend. Eight months…

The Solution

A document-forensics and risk-explanation layer for landlords who already collect applications and often already buy a bureau report. They upload the packet — application, pay…

Market Research

The global tenant screening services market is valued at $1.85B in 2025, $1.94B in 2026, and $2.83B by 2034 at a 4.97% CAGR (Business Research Insights). Alternate cuts: $3.28B in…

Competitive Landscape

TransUnion SmartMove — Category default for DIY landlords. Credit, criminal, eviction. Data access is the moat. The report is dense, the UX assumes you know what to do with it…

Business Model

Free ($0) — 1 full packet per month, watermarked card, no applicant comparison — the lead-gen wedge

Recommended Tech Stack

Next.js (App Router) + Vercel — Landlord dashboard, upload UI, marketing site. Server Actions for the analysis job; stream the risk card so it feels instant.

AI Prompts to Build This

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  1. 1. Project Setup

    Build the weekend MVP of "ProofCheck": a small landlord uploads an applicant's documents and gets a short list of things worth checking before signing a lease. It supports a decision. It never approves, denies or scores a person.
    
    Stack: Next.js (App Router), TypeScript, Tailwind, Supabase (Postgres, Row Level Security, Storage, Auth with email magic link), the Anthropic API to read pay stubs, pdf-parse and pdf-lib to read text and metadata. The checks that can be done in code are done in code. Deploy on Vercel.
    
    Tables (Row Level Security on, a landlord reads only their own rows):
    - properties(id, user_id, address, rent_cents)
    - applicants(id, property_id, label, claimed_income_cents, claimed_employer) label is a short tag such as "Applicant A"; no other personal details are stored
    - packets(id, applicant_id, file_path, sha256, uploaded_at, doc_kind) uploaded_at is set by the server
    - findings(id, packet_id, kind, severity, evidence_quote, explanation, human_check, confidence) kind is metadata, income, employment or inconsistency; severity is info, warn or high
    
    Screens: /login, /properties, /applicants/[id] (upload and the findings card), /applicants/[id]/checklist (printable).
    Env vars (names only): NEXT_PUBLIC_SUPABASE_URL, NEXT_PUBLIC_SUPABASE_ANON_KEY, SUPABASE_SERVICE_ROLE_KEY (server only), ANTHROPIC_API_KEY.
    
    Do not build: billing, plans or a portfolio tier, a composite score, ranking or comparing applicants, public records or eviction searches, credit data, automatic rejection.
    Done when: npm run dev starts, you can sign in, and the four tables exist with Row Level Security on.
  2. 2. Core Feature

    Build the one feature that proves ProofCheck: flags that quote their evidence and say what a human should verify.
    1. Upload a PDF (pay stub, bank statement or employment letter) to a private bucket. Compute and store its sha256 and set uploaded_at on the server.
    2. In code, read the PDF metadata and text: producer and creator tools, creation and modification dates, page count and font names. Raise a flag when the modification date is later than the creation date by more than a day, when the file was created within 2 days before the upload, or when a one-page stub uses more than 3 font families.
    3. For pay stubs, send the text to the Anthropic API with a strict JSON schema { employer_name, gross_per_period, pay_frequency, ytd_gross, quotes: string[] }. Instruct it to ignore names, addresses, age and any family or protected detail, and to use only figures in the document.
    4. Check each quote in code: it must appear in the extracted text, or the field is dropped. Compute in code the income implied by the stub, its difference from claimed_income_cents, and the rent to income ratio.
    5. Save findings. Each has evidence_quote or the metadata value, a plain explanation and a human_check line such as "Call the employer on a number you find yourself, not the one on the stub".
    6. Render a card of 3 to 7 bullets, each tied to a finding, then a printable verify-before-lease checklist. Every card carries: "Decision support only. Not a consumer report. Not legal advice. The landlord makes the housing decision."
    Rules: never output approve, deny or a score. Log every model response for later review. A Delete applicant button removes the files and findings.
    Empty state: a new applicant shows the upload box and the list of documents that help.
    Done when: a test PDF edited after creation raises the metadata flag, a stub whose income differs from the claim by over 10 percent raises an income flag with a real quote, a fabricated quote is dropped, and no screen shows approve, deny or a score.
  3. 3. Landing Page

    Build a one-page landing site for ProofCheck, document checking for small landlords.
    Hero: "Check the story, not just the score." Sub: "Upload the application and pay stubs. Get a short list of things worth verifying before you hand over the keys. You make the decision." One button: Join the waitlist.
    Sections: a scene (a patched PDF and a phone number that goes nowhere), a sample findings card with an evidence quote and a "verify this" line, how it works in four steps (upload, check, review, verify), and a trust block (decision support only, not a consumer report, no approve or deny, no scoring of people). An FAQ on what is stored, how to delete an applicant and why a lawyer should confirm how housing rules apply to you.
    Waitlist: store the email in a waitlist table in Supabase. No other service.
    Style: Geist, a dark desk-like background, one aubergine accent, no people and no unreadable interface text.
    Done when: the page renders on a phone and a submitted email appears in the waitlist table.
  4. 4. Branding Package

    Use a design or image tool for this one. A coding agent cannot draw a logo.
    Brand for ProofCheck: a wordmark and an icon that suggest a document with a magnifier over one line.
    Colors: deep ink, off-white and one aubergine. Type: Geist, with IBM Plex Mono for quoted evidence.
    Deliverables: wordmark, icon, three finding chips (info, check, high) that differ by shape as well as color, a findings card layout that always shows the decision-support line, and one launch graphic.
    Done when: each deliverable is saved in one folder and the finding chips are distinguishable without color.