15 E-Commerce APIs to Integrate With in 2026: Shopify, WooCommerce, BigCommerce, and Unified Commerce APIs
March 23, 2026
E-commerce is one of the broadest integration categories in SaaS.
A single product may need to connect to storefronts, marketplaces, catalog systems, review platforms, inventory tools, fulfillment systems, reservation platforms, and financial backends—all at once. That is what makes commerce integrations so valuable, and so difficult to support cleanly.
Platforms like Shopify, WooCommerce, BigCommerce, Amazon Seller Central, and Walmart Marketplace all expose commerce data differently. Products, variants, collections, stock levels, locations, reviews, and sales channels rarely map neatly from one system to another.
This guide covers the top e-commerce APIs to integrate with in 2026, the most important use cases in the category, the challenges of building these integrations directly, and why more teams are moving toward Unified Commerce APIs instead of supporting each platform one by one.
What is an e-commerce API?
An [e-commerce API](/commerce) gives developers programmatic access to commerce data and workflows.
That often includes:
- products and variants
- collections and catalogs
- inventory and stock levels
- store and warehouse locations
- reviews and ratings
- reservations and availability
- sales channels and marketplaces
These APIs are used to build:
- product sync tools
- marketplace management products
- inventory and catalog platforms
- review aggregation tools
- e-commerce analytics dashboards
- multichannel commerce operations
- AI-powered commerce assistants
Why SaaS products integrate e-commerce APIs
Commerce data touches many workflows beyond the storefront itself.
SaaS products often need to connect e-commerce platforms with:
- ERP and accounting systems
- shipping and fulfillment tools
- marketplaces
- ad platforms
- analytics and BI tools
- CRM and customer data platforms
- AI agents and workflow automation
Common use cases include:
Product catalog synchronization
Sync products and variants across multiple stores, marketplaces, or internal systems.
Inventory synchronization
Keep stock levels aligned across channels to avoid overselling.
Multichannel commerce reporting
Aggregate catalog, review, and inventory data across platforms into one dashboard.
Marketplace operations
Connect storefronts with channels like Amazon, Walmart, or other sales endpoints.
Review aggregation
Pull customer reviews into centralized analytics or moderation workflows.
Availability and reservation workflows
Support commerce-adjacent experiences like bookings, dining, or appointment inventory.
Top 15 e-commerce APIs to integrate with in 2026
Below are some of the most important commerce APIs SaaS teams commonly need to support.
1. Shopify API
Shopify is one of the most important e-commerce APIs to support.
It is frequently used for:
- product and variant sync
- inventory visibility
- catalog and collection management
- storefront analytics
- multichannel commerce tooling
For most SaaS teams serving merchants, Shopify is table stakes.
2. WooCommerce API
WooCommerce is still widely used by businesses that want more control over their commerce stack.
Common use cases:
- product and category sync
- order and catalog tooling
- reviews and customer feedback
- inventory workflows
3. BigCommerce API
BigCommerce is especially important for larger merchants and more structured commerce operations.
Typical uses:
- product and inventory sync
- multistore management
- catalog integrations
- analytics and reporting
4. Amazon Seller Central API
Amazon Seller Central SP-API documentation
Amazon Seller Central is essential for marketplace operations.
Common use cases:
- listing and catalog sync
- marketplace inventory management
- cross-channel reporting
- seller operations tooling
5. Walmart Marketplace API
Walmart matters for teams supporting marketplace expansion and multichannel retail operations.
Typical uses:
- product listing sync
- inventory updates
- marketplace reporting
- channel analytics
6. Squarespace Commerce API
Squarespace developer documentation
Squarespace is relevant for smaller brands, creators, and storefront-first businesses.
Common uses:
- product sync
- inventory visibility
- order and catalog tooling
- storefront data aggregation
7. Square API
Square is important because it bridges commerce, payments, and sometimes point-of-sale workflows.
Typical uses:
- item and inventory sync
- catalog management
- location-based commerce operations
- in-store plus online workflows
8. ShipStation API
ShipStation is not a storefront, but it is critical to many commerce workflows.
Common uses:
- fulfillment operations
- shipping integrations
- order routing
- warehouse and logistics tooling
9. Shippo API
Shippo is another important logistics and shipping API often connected to commerce products.
Common use cases:
- shipping automation
- order fulfillment workflows
- label generation and tracking
- logistics analytics
10. Akeneo API
Akeneo matters for product information management and catalog workflows.
Typical uses:
- PIM integrations
- product catalog normalization
- variant and asset syndication
- multichannel product publishing
11. Salsify API
Salsify developer documentation
Salsify is important for product experience management and catalog distribution.
Common uses:
- catalog and content sync
- product data standardization
- channel publishing
12. Yotpo API
Yotpo is often critical for reviews, user-generated content, and customer feedback workflows.
Typical uses:
- review aggregation
- ratings analysis
- commerce feedback tooling
- social proof and merchandising workflows
13. Yelp API
Yelp is relevant for location-based commerce, hospitality, and review-heavy products.
Common uses:
- location and ratings data
- review monitoring
- multi-location commerce analytics
14. OpenTable API
OpenTable matters for reservation-based commerce and hospitality workflows.
Typical uses:
- reservations
- availability sync
- location and capacity management
- guest flow tooling
15. SevenRooms / resOS and reservation commerce tools
These platforms matter when commerce includes bookings, hospitality, or reservation inventory.
Typical uses:
- reservation sync
- availability management
- guest and location operations
- hospitality data workflows
Other commerce APIs teams often need
Depending on customer demand, teams may also need support for:
That overlap is one reason commerce is rarely just 'commerce.' It often blends into accounting, shipping, reservations, payments, and marketplaces.
Challenges with e-commerce API integrations
E-commerce APIs are difficult to support well because the category is broad and fragmented.
Products and variants are modeled differently
Every provider has its own structure for:
- products
- variants
- options
- media
- collections
- inventory references
Even basic product sync becomes provider-specific very quickly.
Inventory is hard across channels
Inventory is rarely just one number.
It may be:
- location-specific
- channel-specific
- warehouse-specific
- affected by reservations, returns, or bundles
That makes cross-platform inventory sync especially tricky.
Reviews, reservations, and locations complicate the category
Commerce does not stop at catalog and stock.
Once you add:
- reviews
- store locations
- reservations
- availability
- sales channels
the object model becomes much broader than a basic storefront integration.
Different auth and permissions
Every platform has different:
- OAuth requirements
- app review processes
- account models
- marketplace permissions
Maintenance grows fast
Once you support multiple commerce systems directly, you take on:
- different schemas
- different auth flows
- different webhook payloads
- different lifecycle changes
- ongoing API version maintenance
The role of Unified Commerce APIs
This is where Unified Commerce APIs become much more valuable.
Instead of building separate integrations for Shopify, WooCommerce, BigCommerce, Amazon Seller Central, Walmart, Akeneo, ShipStation, Yotpo, and others, a Unified API gives you one interface across a fragmented category.
That means:
- one integration
- one auth experience
- one schema for core commerce objects
- one observability layer
- less ongoing maintenance
For SaaS teams that want broad commerce coverage without rebuilding their product logic per provider, this is a much more scalable model.
Build once with the Unified Commerce API
The Unified Commerce API gives developers access to 35+ e-commerce integrations through a single standardized API.
Supported platforms include:
- Shopify
- WooCommerce
- BigCommerce
- Amazon Seller Central
- Walmart
- Squarespace
- Square
- ShipStation
- Shippo
- Akeneo
- Salsify
- Yotpo
- Yelp
- OpenTable
- SevenRooms
- and more
Unified Commerce objects
Unified standardizes key commerce objects including:
- Item Variants
- Items
- Collections
- Inventory
- Locations
- Reviews
- Reservations
- Availability
- Sales Channels
This makes it possible to build one product experience across many commerce systems without maintaining a separate model for each provider.
Why Unified is different
Many integration approaches still rely on:
- sync jobs
- cached product and inventory data
- fragmented auth flows
- shallow support across commerce-adjacent objects
Unified uses a real-time, pass-through architecture.
That means:
- every request hits the source platform live
- no stale cache layer
- no sync lag
- read and write support across supported objects
- native and virtual webhooks for near-real-time workflows
Unified is also zero-storage by design, so customer commerce data is not stored at rest by the integration layer.
That matters for teams handling sensitive merchant data, regional requirements, and customer environments where compliance scope matters.
What you can build with it
With Unified, teams can build:
- multichannel product sync tools
- inventory synchronization platforms
- commerce analytics dashboards
- marketplace management products
- review aggregation tools
- reservation and availability workflows
- AI-powered commerce assistants
without rebuilding the commerce category provider by provider.
Why not just build each commerce integration directly?
You can, but this category becomes expensive quickly.
For every provider you support, you need to handle:
- new auth patterns
- different product and inventory schemas
- different webhook systems
- different marketplace rules
- ongoing API maintenance
That cost grows much faster than most teams expect because commerce touches so many adjacent systems.
A Unified Commerce API removes much of that repeated infrastructure work and keeps your product architecture cleaner as you expand.
Final thoughts
E-commerce APIs are foundational for catalog, inventory, marketplace, review, and reservation workflows, but the category is broad enough that direct integrations become difficult to scale.
That is why more SaaS teams are moving toward Unified Commerce APIs.
If you need real-time, read/write access to commerce data across Shopify, WooCommerce, BigCommerce, Amazon Seller Central, Walmart, and many more systems, Unified.to gives you a much faster and more scalable way to support those workflows.