API Usage & Billing System - Take Home Project

Context

SuperDoc provides document conversion services through its API endpoints (e.g., /convert for converting documents between formats like DOCX to PDF, PDF to DOCX, DOCX to HTML). We need a system to track API usage and handle billing.

Project Overview

Design and implement a usage tracking and billing system that will:

• Track API calls to document conversion endpoints
• Manage usage quotas
• Calculate billing based on usage

Core Requirements

1. Usage Tracking

Track essential metrics for document conversions:

{
  "account_id": "string",
  "endpoint": "string",
  "timestamp": "datetime",
  "status": "success|failure"
}

2. Billing System

Implement simple tiered pricing:

• Free tier: 100 requests/month
• Pro tier: $0.10 per request

3. Technical Requirements

• Use Python with FastAPI
• Implement proper authentication
• Handle concurrent requests
• Include error handling
• Add logging

Required Deliverables

1. API Implementation

• Complete REST API with endpoints for:
  • Usage tracking
  • Usage statistics retrieval
  • Quota checking
  • Billing calculations
• Authentication mechanism
• Input validation
• Error handling
• Rate limiting (optional)

2. Database

• Schema design
• Indexes for performance (optional)

3. Tests

• Unit tests
• Integration tests
• Test coverage report
• Performance tests (optional)

4. Documentation

• API documentation (OpenAPI/Swagger)
• Setup instructions
• Architecture overview
• Design decisions explanation
• Future improvements

5. Code Quality

• Clean, maintainable code
• Proper error handling
• Logging
• Type hints
• Comments where necessary

Evaluation Criteria

API Design (30%)

• RESTful principles
• Authentication implementation
• Error handling
• Documentation quality

Code Quality (25%)

• Clean code practices
• Error handling
• Testing coverage
• Type safety

System Design (25%)

• Database schema
• Concurrency handling
• Performance considerations
• Scalability approach

Documentation (20%)

• Setup instructions
• Architecture explanation
• Design decisions
• Future improvements

Time Expectation

• Core requirements: 6-8 hours
• Additional features: 2-4 hours (optional)

Submission Guidelines

1. Provide source code in a Git repository
2. Include comprehensive README.md
3. Document all assumptions and decisions
4. Note any shortcuts taken due to time constraints
5. Suggest future improvements

Questions?

If you need any clarification about the requirements, please don't hesitate to ask. We want to ensure you can showcase your skills effectively.