E-commerce API Monitoring
Your e-commerce platform depends on APIs for everything — product catalogs, inventory, shopping carts, and checkout. When these APIs fail or return incorrect data, you lose sales and frustrate customers.
The Problem
E-commerce API failures are costly:
- Wrong prices displayed — pricing API returns stale data
- Inventory sync errors — products show as available but aren't
- Checkout failures — payment processing goes down
- Slow product pages — catalog API response times spike
Traditional uptime monitoring catches when your API is completely down. But what about when it returns a 200 OK with incorrect data?
How APIAssert Helps
APIAssert validates your API responses, not just their availability.
Monitor Product APIs
Ensure your product catalog returns correct data:
Monitor: GET /api/products/featured
Assertions:
✓ $.products.length > 0
✓ $.products[*].price > 0
✓ $.products[*].in_stock exists
✓ Response time < 500ms
Catch issues like:
- Empty product listings
- Missing price data
- Null inventory values
- Slow response times
Monitor Inventory APIs
Validate inventory sync is working:
Monitor: GET /api/inventory/SKU-12345
Assertions:
✓ $.quantity >= 0
✓ $.last_updated within 1 hour
✓ $.warehouse_id exists
Catch issues like:
- Negative inventory counts
- Stale inventory data
- Missing warehouse mappings
Monitor Checkout Flow
Ensure checkout APIs are operational:
Monitor: POST /api/checkout/validate
Assertions:
✓ $.valid == true
✓ $.payment_methods.length > 0
✓ $.shipping_options.length > 0
Catch issues like:
- Cart validation failures
- Missing payment options
- Broken shipping calculations
Real-World Example
The Scenario
An online retailer's product API occasionally returns empty arrays during high traffic. The API returns 200 OK, so uptime monitors don't alert. Customers see "No products found" on the homepage.
The APIAssert Solution
Monitor: Production Product API
URL: https://api.store.com/products/featured
Method: GET
Interval: 1 minute
Regions: US East, US West, Europe
Assertions:
- $.products must be array
- $.products.length must be > 0
- $.products[0].id must exist
- $.products[0].price must be > 0
- Response time must be < 1000ms
Alerts:
- Slack: #ecommerce-alerts
- PagerDuty: E-commerce On-Call
The Outcome
- Issue detected in 60 seconds (not hours later from customer complaints)
- On-call engineer alerted immediately via PagerDuty
- Root cause identified — database connection pool exhaustion
- Fix deployed before significant revenue impact
Key API Endpoints to Monitor
Product Catalog
| Endpoint | What to Assert |
|---|---|
| GET /products | Products array not empty |
| GET /products/:id | Product data complete |
| GET /categories | Categories exist |
| GET /search | Results match query |
Inventory
| Endpoint | What to Assert |
|---|---|
| GET /inventory/:sku | Quantity is valid number |
| GET /availability | Stock status accurate |
| POST /reserve | Reservation succeeds |
Cart & Checkout
| Endpoint | What to Assert |
|---|---|
| POST /cart/add | Item added successfully |
| GET /cart | Cart totals correct |
| POST /checkout | Order created |
| GET /payment/methods | Options available |
Order Management
| Endpoint | What to Assert |
|---|---|
| GET /orders/:id | Order status valid |
| POST /orders/:id/cancel | Cancellation succeeds |
| GET /tracking/:id | Tracking data present |
Best Practices
Monitor from Multiple Regions
Your customers are global. Monitor from regions where they shop:
- US East & West — North American customers
- Europe — EU customers (also good for GDPR compliance checks)
- Asia — Asia-Pacific customers
Set Appropriate Intervals
- Product APIs: Every 1-2 minutes (impacts all visitors)
- Checkout APIs: Every minute (directly impacts sales)
- Inventory sync: Every 5 minutes (depends on sync frequency)
- Search API: Every 2-3 minutes (important for discovery)
Create Alert Hierarchies
Not all failures are equal:
| Severity | Alert To | Example |
|---|---|---|
| Critical | PagerDuty (immediate) | Checkout API down |
| High | Slack + Email | Product API empty results |
| Medium | Slack | Inventory API slow |
| Low | Email digest | Non-critical API warnings |
Test During Sales Events
Before Black Friday, Cyber Monday, or any major sale:
- Increase check frequency temporarily
- Add extra assertions for expected high-traffic behavior
- Test from more regions to catch CDN issues
- Lower alert thresholds for faster response
Getting Started
- Identify critical APIs — What would hurt most if it failed?
- Create monitors — Start with checkout and product APIs
- Add assertions — Validate data, not just status codes
- Set up alerts — Route to the right team
- Monitor and iterate — Add more endpoints as you learn
Related Use Cases
- Payment API Monitoring — Deep dive into payment flow monitoring
- Third-party API Monitoring — Monitor vendor APIs you depend on
