tutorial

Build an AI Lease Analyzer App with the AI Pass SDK

Build an AI lease analyzer web app with the AI Pass SDK. Explains every clause in plain English, flags red flags, and suggests negotiation questions. Full code included.

EiliyaMarch 23, 20265 min read

Build an AI Lease Analyzer App with the AI Pass SDK

Document analysis is one of the highest-value AI applications — people will pay to have complex contracts explained in plain language. A lease analyzer is particularly in-demand: millions of people sign leases every year without fully understanding what they're agreeing to.

This tutorial builds a complete AI lease analyzer web app with the AI Pass SDK.

Prerequisites

HTML/JavaScript basics
AI Pass account (sign up at aipass.one)
Client ID from Developer Dashboard

Step 1: Get Your Client ID

Log in at aipass.one
Go to Developer Dashboard → OAuth2 Clients
Create a new client called "Lease Analyzer"
Copy your client_XXXX... ID

Step 2: Build the App

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>AI Lease Analyzer</title>
  <script src="https://aipass.one/aipass-sdk.js"></script>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: 'Segoe UI', sans-serif;
      background: #f0f4ff;
      max-width: 860px;
      margin: 0 auto;
      padding: 2rem;
      color: #1e293b;
    }
    h1 { color: #1e40af; margin-bottom: 0.25rem; }
    .subtitle { color: #64748b; margin-bottom: 2rem; }
    .input-section {
      background: white;
      border-radius: 12px;
      padding: 1.5rem;
      box-shadow: 0 1px 4px rgba(0,0,0,0.08);
    }
    label { font-weight: 600; font-size: 0.875rem; color: #374151; display: block; margin-bottom: 0.5rem; }
    textarea {
      width: 100%;
      min-height: 200px;
      padding: 1rem;
      border: 1px solid #d1d5db;
      border-radius: 8px;
      font-family: monospace;
      font-size: 0.875rem;
      resize: vertical;
      color: #1e293b;
    }
    .options-row { display: flex; gap: 1rem; margin: 1rem 0; flex-wrap: wrap; }
    select {
      padding: 0.5rem 1rem;
      border: 1px solid #d1d5db;
      border-radius: 8px;
      font-size: 0.9rem;
      background: white;
    }
    button {
      background: #1e40af;
      color: white;
      border: none;
      padding: 0.875rem 2rem;
      border-radius: 8px;
      font-size: 1rem;
      font-weight: 600;
      cursor: pointer;
      width: 100%;
      margin-top: 0.75rem;
    }
    button:disabled { background: #93c5fd; cursor: not-allowed; }
    #status { text-align: center; margin: 1rem 0; color: #6b7280; }
    .results {
      margin-top: 1.5rem;
      display: none;
    }
    .card {
      background: white;
      border-radius: 12px;
      padding: 1.5rem;
      margin-bottom: 1rem;
      box-shadow: 0 1px 4px rgba(0,0,0,0.08);
    }
    .card h2 { font-size: 1rem; color: #1e40af; margin-bottom: 0.75rem; padding-bottom: 0.5rem; border-bottom: 2px solid #dbeafe; }
    .card-content { line-height: 1.7; color: #374151; white-space: pre-wrap; }
    .red-flag { background: #fff1f2; border-left: 4px solid #ef4444; padding: 0.75rem 1rem; border-radius: 0 8px 8px 0; margin: 0.5rem 0; }
    .green-flag { background: #f0fdf4; border-left: 4px solid #22c55e; padding: 0.75rem 1rem; border-radius: 0 8px 8px 0; margin: 0.5rem 0; }
  </style>
</head>
<body>
  <h1>📋 AI Lease Analyzer</h1>
  <p class="subtitle">Understand every clause before you sign</p>

  <div class="input-section">
    <label>Paste Your Lease Text *</label>
    <textarea id="leaseText" placeholder="Paste your full lease agreement here. The more text you provide, the more thorough the analysis."></textarea>
    
    <div class="options-row">
      <div>
        <label style="margin-bottom:0.3rem">Lease Type</label>
        <select id="leaseType">
          <option>Residential Rental</option>
          <option>Commercial / Office</option>
          <option>Month-to-Month</option>
          <option>Student Housing</option>
          <option>Commercial Retail</option>
        </select>
      </div>
      <div>
        <label style="margin-bottom:0.3rem">Focus</label>
        <select id="focusArea">
          <option>Full Analysis</option>
          <option>Red Flags Only</option>
          <option>Financial Terms</option>
          <option>Termination & Exit</option>
          <option>Landlord Rights & Access</option>
        </select>
      </div>
    </div>

    <button id="analyzeBtn" onclick="analyzeLease()">🔍 Analyze Lease</button>
  </div>

  <p id="status"></p>

  <div class="results" id="results">
    <div class="card">
      <h2>📌 Summary</h2>
      <div class="card-content" id="summary"></div>
    </div>
    <div class="card">
      <h2>🚩 Red Flags</h2>
      <div id="redFlags"></div>
    </div>
    <div class="card">
      <h2>📖 Clause-by-Clause Breakdown</h2>
      <div class="card-content" id="clauses"></div>
    </div>
    <div class="card">
      <h2>❓ Questions to Ask Before Signing</h2>
      <div class="card-content" id="questions"></div>
    </div>
  </div>

  <script>
    AiPass.initialize({
      clientId: 'YOUR_CLIENT_ID',
      requireLogin: true,
      darkMode: false
    });

    async function analyzeLease() {
      const text = document.getElementById('leaseText').value.trim();
      if (!text || text.length < 100) {
        alert('Please paste your lease text (at least a few paragraphs).');
        return;
      }

      const btn = document.getElementById('analyzeBtn');
      const status = document.getElementById('status');
      btn.disabled = true;
      status.textContent = '⏳ Analyzing your lease... (30-60 seconds)';
      document.getElementById('results').style.display = 'none';

      const leaseType = document.getElementById('leaseType').value;
      const focusArea = document.getElementById('focusArea').value;

      const prompt = `Analyze this ${leaseType} lease agreement with focus on: ${focusArea}.

Provide your analysis in exactly this format:

SUMMARY:
[2-3 sentence overview: lease type, duration, rent amount, key dates]

RED FLAGS:
[List each red flag as: 🚩 [Clause Name]: [What it means and why it's concerning]]
[If no red flags, write "No major red flags identified."]

CLAUSE BREAKDOWN:
[For each major section: Section Name — Plain English explanation of what the tenant is agreeing to]

QUESTIONS TO ASK:
[5-7 specific questions the tenant should ask the landlord before signing]

LEASE TEXT:
${text.substring(0, 8000)}`;

      try {
        const result = await AiPass.generateCompletion({
          model: 'gpt-5',
          temperature: 1,
          max_tokens: 16000,
          messages: [
            {
              role: 'system',
              content: 'You are a tenant rights expert who explains legal documents in plain, accessible language. You identify clauses that are unusual, one-sided, or potentially harmful to tenants. You do not provide legal advice but help people understand what they are reading.'
            },
            { role: 'user', content: prompt }
          ]
        });

        const content = result.choices[0].message.content;

        // Parse sections
        const summaryMatch = content.match(/SUMMARY[:\s]+([\s\S]*?)(?=RED FLAGS:|$)/i);
        const flagsMatch = content.match(/RED FLAGS[:\s]+([\s\S]*?)(?=CLAUSE BREAKDOWN:|$)/i);
        const clausesMatch = content.match(/CLAUSE BREAKDOWN[:\s]+([\s\S]*?)(?=QUESTIONS TO ASK:|$)/i);
        const questionsMatch = content.match(/QUESTIONS TO ASK[:\s]+([\s\S]*?)$/i);

        document.getElementById('summary').textContent = summaryMatch ? summaryMatch[1].trim() : '';

        // Format red flags
        const flagsText = flagsMatch ? flagsMatch[1].trim() : '';
        const flagsContainer = document.getElementById('redFlags');
        flagsContainer.innerHTML = '';
        if (flagsText && !flagsText.toLowerCase().includes('no major red flags')) {
          flagsText.split('\n').filter(l => l.trim()).forEach(flag => {
            const div = document.createElement('div');
            div.className = flag.includes('🚩') ? 'red-flag' : '';
            div.textContent = flag;
            flagsContainer.appendChild(div);
          });
        } else {
          const ok = document.createElement('div');
          ok.className = 'green-flag';
          ok.textContent = '✅ No major red flags identified in this lease.';
          flagsContainer.appendChild(ok);
        }

        document.getElementById('clauses').textContent = clausesMatch ? clausesMatch[1].trim() : '';
        document.getElementById('questions').textContent = questionsMatch ? questionsMatch[1].trim() : '';

        document.getElementById('results').style.display = 'block';
        status.textContent = '✅ Analysis complete. Review your results below.';
      } catch (err) {
        status.textContent = '❌ Error: ' + err.message;
      }
      btn.disabled = false;
    }
  </script>
</body>
</html>

Key Notes

temperature: 1 and max_tokens: 16000 are required for GPT-5
Lease text is truncated to 8,000 characters — for longer leases, process in chunks
The gpt-5 model provides the best document understanding quality

Deploy & Earn

Self-host: Single HTML file, works on any static host.

Publish on AI Pass: Submit at Developer Dashboard → Apps. Earn 50% commission on every lease analysis. This is a high-value, recurring use case — people analyze leases before every move.

Build an AI Lease Analyzer App with the AI Pass SDK

Build an AI Lease Analyzer App with the AI Pass SDK

Prerequisites

Step 1: Get Your Client ID

Step 2: Build the App

Key Notes

Deploy & Earn

Resources

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