FinAdvisor — Personal Finance Chatbot

A domain-specific LLM chatbot powered by Google Gemini 1.5 Flash (free tier). It answers only personal finance and budgeting questions — all other topics are refused by the system prompt.

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Getting your free Gemini API key

1. Go to https://aistudio.google.com/app/apikey
2. Sign in with your Google account
3. Click "Create API Key"
4. Copy the key

Free tier limits (no credit card needed):

• 15 requests per minute
• 1,500 requests per day
• 1 million tokens per minute

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Setup

1. Add your API key

Open .env.local and replace the placeholder:

GEMINI_API_KEY=your_actual_key_here

2. Install dependencies

npm install

3. Run the development server

npm run dev

4. Open in browser

http://localhost:3000

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Build for production

npm run build
npm start

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How it works

Domain restriction

The system prompt sent to Gemini strictly defines the allowed topics:

• Budgeting and expense tracking
• Saving strategies and emergency funds
• Debt management (avalanche, snowball methods)
• Investing basics (index funds, ETFs, retirement accounts)
• Credit scores and credit health
• Financial planning (net worth, FIRE, insurance basics)
• Tax basics as they relate to personal finance

If a user asks anything outside this domain, the system prompt instructs Gemini to respond with a fixed redirect message and nothing else.

API architecture

• The Gemini API call happens in a Next.js API route (app/api/chat/route.ts) — server-side only
• The API key is never exposed to the browser
• Full conversation history is sent on each request so Gemini maintains context

Model settings

• Model: gemini-1.5-flash (fastest, free tier)
• Temperature: 0.4 (precise, low variability)
• Max output tokens: 1024

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Project structure

finbot/
  app/
    page.tsx              ← frontend UI
    layout.tsx            ← root layout
    globals.css           ← base styles
    api/
      chat/
        route.ts          ← Gemini API call + system prompt
  .env.local              ← your API key goes here (never commit this)
  package.json
  next.config.js
  tsconfig.json
  tailwind.config.js
  postcss.config.js
  .gitignore
  README.md