Allowance — Give Your AI an Allowance, Not Your Wallet
Inspiration
AI agents are becoming capable of shopping and making decisions, but giving an AI unrestricted access to money creates a serious trust problem.
We wanted to build a different experience: an AI that can plan purchases, but never gets unrestricted control over the user's wallet.
What it does
Allowance is an AI-powered shopping agent with user-defined spending limits and PayPal-powered checkout.
Users describe what they need in natural language. The AI proposes a shopping cart, while an independent policy engine checks spending limits, categories and purchase restrictions.
The user remains in control of the final payment.
Our core principle is simple:
Intent is not authority.
How it works
- The user describes a shopping request.
- The AI generates a proposed cart.
- The backend validates products, quantities and prices.
- The deterministic policy engine evaluates the purchase.
- Invalid or over-budget purchases are rejected.
- Eligible purchases proceed to user-approved PayPal checkout.
- The backend verifies payment capture before recording a successful transaction.
- The transaction ledger and receipt provide an audit trail.
How we built it
Allowance uses a lightweight web application and Node.js backend.
The AI integration uses Anthropic Claude for natural-language shopping requests and cart planning.
PayPal Sandbox provides the payment integration.
A separate JavaScript policy engine handles spending authorization. Cryptographic signing and transaction verification help protect the purchase workflow.
The interface uses a distinctive peach, lime-green and coral design with a transaction dashboard and shopping assistant.
Challenges we ran into
The biggest challenge was separating AI recommendations from financial authorization.
An AI-generated shopping plan must never be trusted as payment authority. We designed the workflow so that the backend validates the cart, evaluates the rules and requires explicit user approval before payment.
We also focused on preventing incorrect amounts, expired purchase mandates and unverified payment success.
Accomplishments we're proud of
- Built a natural-language shopping experience.
- Designed a separate deterministic spending policy engine.
- Integrated a user-controlled payment workflow around PayPal Sandbox.
- Created a financial transaction dashboard.
- Designed a purchase-verification and audit workflow.
Only features verified in the final build should be represented as completed.
What we learned
AI autonomy and financial authority should be separate.
An AI agent can recommend and plan, but financial decisions require deterministic controls, transparent rules and explicit human approval.
What's next
We plan to expand product discovery, improve shopping recommendations, strengthen persistent transaction auditing and make Allowance available as a reliable personal purchasing assistant.
Built With
- ag
- agents
- ai
- anthropic
- api
- claude
- cryptography
- css
- express.js
- grid
- hmac
- html
- javascript
- node.js
- paypal
- restapi
- sandbox
