DIY Developer Guide: Building Custom Integrations for Amazon FBA
A comprehensive guide to building custom integrations with Amazon FBA using SP-API for inventory management, order fulfillment, and shipment tracking.
Overview
Amazon FBA (Fulfillment by Amazon) enables sellers to leverage Amazon's fulfillment network. This guide covers building custom integrations using Amazon's Selling Partner API (SP-API) for inventory, orders, and shipment management.
Prerequisites
- Amazon Seller Central account with SP-API access
- Familiarity with RESTful APIs, OAuth 2.0 (LWA), and JSON data structures
- Tools: Postman, Amazon SP-API Documentation, AWS SDK
Step 1: Authentication
Amazon SP-API uses Login with Amazon (LWA) OAuth 2.0. Obtain refresh tokens and exchange for short-lived access tokens.
Step 2: Endpoint Discovery and Data Mapping
Common API Resources: FBA Inventory, Inbound Shipments, Orders, Fulfillment, Reports, Feeds.
Map Amazon ASINs and SKUs to your internal catalog. Handle multi-marketplace configurations.
Step 3: Building Integration Flows
- Inbound (to Amazon): Create inbound shipments, submit feeds, update listings
- Outbound (from Amazon): Retrieve orders, inventory levels, shipment tracking, settlement reports
Step 4: Error Handling and Rate Limiting
SP-API enforces strict rate limits with burst and restore rates. Implement token bucket algorithms and handle throttling (HTTP 429) gracefully.
Step 5: Security Best Practices
- Store LWA credentials and refresh tokens in secure vaults
- Use IAM roles with minimal permissions
- Encrypt all data in transit and at rest
- Rotate credentials periodically
Step 6: Testing and Validation
- Use SP-API sandbox for initial testing
- Validate inventory reconciliation across FBA and merchant-fulfilled
- Test feed submission and processing status workflows
Step 7: Deployment and Monitoring
- Monitor API quotas and throttling rates
- Alert on feed processing errors
- Track inventory discrepancies between systems
When to Use a Managed Platform
For sellers managing FBA alongside other channels and ERPs, a managed integration platform like APIWORX handles the complexity of multi-marketplace orchestration at scale.
