Unified APIs for eCommerce Data: A Guide for Marketplaces

August 27th, 2023
Written by
Daniel Spataro


Building a marketplace is no small feat. You need to connect buyers and sellers, enable transactions, manage inventory, calculate shipping, process payments, and more. At the heart of it all is data - product information, orders, customers, finances. As a marketplace builder, accessing and unifying this data across services is key, but often complex and time-consuming.

In this guide, we’ll explore how a unified API platform can help you overcome these challenges and build seamless marketplace integrations faster.

The Challenges of Marketplace Data Integration

Marketplaces rely on many services - shopping carts, payment gateways, ERPs, shipping carriers, etc. Each has its own API, protocols, and data formats. Attempting to unify and sync this data leads to a tangled mess of point-to-point connections riddled with compatibility issues.

Engineering teams often run into the following repeated challenges:

  • Schema mismatches - Each API uses different names, structures, and datatypes for the same logical entities like products, customers, and orders. Normalizing this into your database is manual drudgery.
  • Authentication and credentials - You need to securely store and manage API keys and tokens for each connection. Rotate credentials, handle token expiry and refresh, etc.
  • Business logic and transformations - APIs rarely match your internal models. You end up writing lots of transformation code to tweak, combine, split, or validate data.
  • Orchestration - With multiple interconnected flows, you have to carefully orchestrate calls, handle errors/retries, idempotency, and more.
  • Monitoring - Detecting issues across myriad API calls is hard without proper instrumentation and logging.

These problems grow exponentially as you scale and add more services. The result is convoluted spaghetti code riddled with technical debt.

The Solution: A Unified API Layer

A unified API platform alleviates these issues by sitting between your apps and external services. It exposes a single well-defined schema for each entity like products, orders, shipments, etc. You code to these canonical schemas rather than individual APIs.

The platform handles all integration logic behind the scenes:

  • Authentication and keys
  • Calling diverse APIs
  • Normalizing data into the unified schema
  • Orchestration and error handling
  • Logging and monitoring

Your code is cleaner without business logic clutter. Adding new services doesn’t increase complexity. The unified APIs act as a facade insulating your app.

Key Benefits of Unified APIs

Adopting unified APIs delivers manifold benefits:

Faster integration with services

Connecting to a new API can now be done declaratively without code. A unified schema maps to the target API under the hood. Adding another shipping carrier or payment processor barely takes any effort.

Clean separation of concerns

Your app code focuses purely on business logic and UX. Integration logic moves into the platform leading to modular code.

Consistent data models

Your data layer works with consistent structures. There’s no need to reconcile different API responses. Models remain stable even as third-party APIs change.

Robust error handling

Network failures, API downtimes, throttling errors, and more are handled gracefully. Unified APIs provide consistent fallback logic.

Single source of truth

The unified schemas act as the single source of data. No more syncing disjoint API responses across your app.

Improved developer productivity

Developers no longer waste time on integration drudgery. They can build features faster.

Increased reliability

With robust controls around integration, availability and correctness improves. Monitoring and logs provide actionable insight.

Reduced technical debt

Legacy integration tangles can be slowly untangled by adopting unified APIs. It limits future debt accumulation.

Easy adoption

Unified APIs can be adopted incrementally without rearchitecting everything upfront. Smooth migration avoids disruption.

Key Capabilities of a Unified API Platform

So what key capabilities should you look for in a unified API platform?

  • Declarative API configuration: Smoothly define unified schemas and map them to external APIs through declarative files/UI rather than code.
  • Developer SDKs: Embed simple SDKs in your apps to call unified APIs from frontend and backend code. Support common languages like JavaScript, Python, Java, Go.
  • Transformation engine: Automatically transform data between external API responses and your unified schemas. Handle mismatches, validate data, merge fields etc.
  • Orchestration engine: Schedule and coordinate sequences of API calls with support for branching logic, error handling, retries and idempotency.
  • Authentication: Securely manage API keys and tokens including rotation and expiry. Isolate credentials from app code.
  • Monitoring and analytics: Gain visibility into API performance, volumes, errors etc. Configure alerts for critical failures.
  • API lifecycle: Promote APIs through dev, test, production stages with controls around access and keys.
  • Extensible architecture: Ability to extend with custom middleware, adapters, and components for non-standard use cases.
  • Performance and scalability: High-throughput and low-latency architecture optimized for enterprise scale.

Best Practices for Unified APIs

As you design unified APIs, keep these best practices in mind:

  • Domain-driven design: Structure schemas around business domains (customers, products, orders etc), not technical services.
  • Canonical models: Map multiple APIs to the same schema where logical entities match rather than creating separate schemas.
  • Coarse-grained APIs: Favor fewer coarse-grained APIs versus many fine-grained ones to minimize chatty calls.
  • Idempotent APIs: Ensure API operations are idempotent (can be called repeatedly with same result) wherever applicable.
  • Consistency over performance: Optimize first for consistency; performance optimizations can come later.
  • Loose coupling: Avoid overly tight coupling between APIs. Allow independent extensibility and evolution.
  • Business logic in apps: Keep unified API code minimal with most logic in apps. Enables easier maintenance.
  • Dry runs and mocks: Support dry runs and mock responses during development for easier testing.
  • Monitoring hooks: Instrument APIs with metrics, logs and traces to enable monitoring.
  • Versioning: Support versioning schemas and APIs to allow backward compatibility.
  • Self-documenting: Make APIs self-documenting with OpenAPI or other schemas. Maintain up-to-date docs.

Adopting these principles will maximize long-term maintainability while delivering clean unified APIs to your developers.

Bringing It All Together

Unified APIs abstract away the complexity of disparate services and schemas. They enable marketplace builders to assemble integrations faster without downsides of technical debt or brittle spaghetti code.

Approached thoughtfully, unified APIs can be an invaluable accelerator and enabler for your marketplace platform. You get the speed and flexibility to rapidly connect new services, test ideas, and scale your business. Your developers are free to focus on creating amazing merchant and buyer experiences rather than wrestling with integration drudgery.

There are many ways to implement unified APIs from building in-house to leveraging cloud services. Assess options based on your environment and capability trade-offs. Prioritize developer experience and productivity over customization flexibility.

Start your unified API journey with non-critical domains like shipping and expand from there. As you liberate your developers from integration busywork, you’ll be able to deliver marketplace innovation at a faster clip.