What are CRUD Methods in API Integrations?

CRUD methods in API integrations are the foundation of modern software communication. According to the 2025 State of the API Report by Postman, 82% of organizations have adopted an API-first approach, while 65% already generate revenue from their API programs. As APIs continue to power eCommerce, SaaS, ERP, and marketplace software, understanding CRUD operations has become an essential skill for developers building reliable integrations.

CRUD methods in API represent the four core operations used to manage data: Create, Read, Update, and Delete. These operations map to standard REST API methods and allow software to retrieve, modify, synchronize, and remove data between connected systems. However, choosing the correct HTTP method is not always straightforward. In particular, POST, PUT, and PATCH are often confused because their behavior can overlap depending on the API design.

In this guide, you'll learn how CRUD methods in API work, how they relate to REST API methods, and when to use POST, GET, PUT, PATCH, and DELETE in real-world integration scenarios.

Understanding CRUD Methods in API

CRUD methods in API describe the four core operations used to manage data in software applications: Create, Read, Update, and Delete. In REST APIs, these operations define how client applications interact with server resources, including products, orders, customers, and inventory. As a result, developers can build predictable, scalable, and maintainable integrations.

Each CRUD operation typically corresponds to a specific HTTP method:

• Create – usually performed with a POST request to add a new resource;
• Read – handled with a GET request to retrieve data without modifying it;
• Update – performed with PUT or PATCH requests to modify existing resources;
• Delete – executed with a DELETE request to permanently remove a resource.

Using CRUD methods in API integrations provides a standardized way to exchange data between systems. Consequently, software vendors can simplify maintenance, improve reliability, and ensure consistent communication across multiple eCommerce platforms. This is especially important when building applications that rely on a Shopping Cart API.

Who Uses CRUD Operations in eCommerce APIs?

CRUD operations are essential for many types of eCommerce software, including:

• Shipping software – to create shipments, update delivery statuses, and retrieve shipping information;
• Warehouse Management Systems (WMS) – to synchronize inventory levels, products, and fulfillment data;
• Enterprise Resource Planning (ERP) systems – to manage products, customers, and orders across business processes;
• Product Information Management (PIM) systems – to maintain consistent product information across multiple sales channels;
• Order Management Systems (OMS) – to create, update, and monitor orders throughout the fulfillment process;
• Inventory management software – to synchronize stock levels and reduce the risk of overselling.

Therefore, CRUD methods in API integrations form the foundation of modern eCommerce software. Whether a solution connects online stores, marketplaces, ERP systems, or warehouse platforms, these operations enable reliable data synchronization while reducing manual work. For SaaS providers, implementing CRUD methods correctly is essential for delivering scalable and dependable integrations.

Creating a Resource: POST vs. PUT

Both POST and PUT can create resources, but they are designed for different scenarios. Understanding the difference is essential when working with CRUD methods in API integrations.

POST is typically used when the server generates the identifier for a new resource. The client sends data to a collection endpoint, and the server creates both the resource and its unique URI.

PUT, on the other hand, is commonly used to create or completely replace a resource at a specific URI provided by the client. If the resource already exists, PUT replaces it. Otherwise, some APIs create a new resource at that location.

As a result, POST is generally preferred for creating new resources, while PUT is used when the client already knows the target resource identifier.

CRUD API Methods: PUT vs. PATCH

Developers use both PUT and PATCH to update existing resources when working with CRUD methods in API integrations. Although both HTTP methods modify data, each one serves a different purpose. The right choice depends on how much of the resource needs to change.

PUT replaces the entire resource with a new representation. PATCH updates only specific fields and leaves the remaining data unchanged. Because PATCH transfers less data, developers often choose it for small updates that improve efficiency and reduce network traffic.

Another important difference is idempotency. A PUT request always produces the same result when a client sends the identical request multiple times. PATCH requests may or may not behave the same way because API developers decide how their applications implement partial updates.

Most modern REST APIs support both HTTP methods. Developers typically use PUT for complete resource replacement, while they choose PATCH for partial updates that keep CRUD API operations efficient and predictable.

Idempotency and Safety of CRUD API Methods

Idempotency and safety are two fundamental concepts behind CRUD methods in API design. Developers who understand these principles build reliable integrations that continue to behave consistently, even after retries, network interruptions, or temporary service failures.

An idempotent HTTP method always produces the same result when a client sends the same request multiple times. For example, repeated PUT requests update a resource to the same state without creating duplicates. In contrast, repeated POST requests usually create additional resources, which makes POST a non-idempotent method.

A safe HTTP method never modifies server-side data. GET is the primary safe method because it retrieves information without changing a resource. API designers generally consider PATCH neither safe nor inherently idempotent, although they can implement idempotent PATCH requests when a specific use case requires them.

Developers choose the appropriate HTTP method as part of effective REST API design. By following idempotency and safety principles, software providers create more predictable CRUD API integrations, reduce duplicate operations, and synchronize data more reliably across multiple eCommerce platforms.

Simplify eCommerce CRUD Integrations with API2Cart

If you are a B2B eCommerce software vendor building integrations with shopping carts or marketplaces, API2Cart helps reduce both development time and long-term maintenance. Instead of creating and supporting separate integrations, you can use a single REST API to connect your application with 70+ eCommerce platforms and marketplaces.

API2Cart provides more than 100 API methods that cover the most common CRUD operations for key eCommerce entities, including products, orders, customers, shipments, categories, and more. This enables software providers to build complete synchronization workflows through one consistent integration layer.

For example, developers can use dedicated methods to:

• Create new products with product.add;
• Retrieve product information using product.info or product.list;
• Update existing products with product.update;
• Delete products using product.delete.

The same approach is available for orders, customers, shipments, and many other store entities. Explore the complete list of methods in the API2Cart API documentation and start building integrations faster with a single REST API.

Why B2B Software Vendors Choose API2Cart

API2Cart helps SaaS companies and software vendors accelerate eCommerce integration projects while reducing ongoing maintenance costs. Instead of building and supporting dozens of platform-specific connectors, your team works with one consistent REST API.

• One integration for 70+ platforms. Connect your application to leading shopping carts and marketplaces through a single API.
• Complete CRUD functionality. Create, retrieve, update, and delete products, orders, customers, shipments, and other store data using consistent API methods.
• Lower development and maintenance costs. API2Cart continuously maintains platform compatibility, so your team spends less time updating integrations when eCommerce platforms change.
• Developer-friendly experience. Interactive documentation, SDKs, and responsive technical support help reduce implementation time.
• Secure and reliable data exchange. Authentication, encrypted communication, and a stable infrastructure help ensure dependable data synchronization across connected systems.

As your customers adopt new shopping carts or marketplaces, API2Cart maintains the platform connections for you. This allows your developers to focus on building new product features instead of maintaining dozens of individual integrations.

CRUD API Example with API2Cart

Learning CRUD methods is only the first step. Software vendors also need to implement CRUD API operations consistently across multiple eCommerce platforms. API2Cart simplifies this task by providing a single REST API with consistent CRUD methods for creating, retrieving, updating, and deleting store data across 70+ eCommerce platforms and marketplaces.

Instead of learning a different API for every shopping cart, developers use one integration layer to manage products, orders, customers, shipments, categories, and many other entities. Explore every available CRUD API endpoint in the API2Cart API documentation.

The examples below show how developers perform CRUD API operations with API2Cart. Review the request structure to understand which parameters the client sends to the API, then examine the response structure to see which data the API returns after each successful operation.

Create a Product with a CRUD API POST Request

The Product Add method demonstrates how a new product can be created through a single API request, regardless of the connected eCommerce platform.

Request Example

The request body contains the product information that will be sent to the connected store. Required and optional parameters define the product's attributes, pricing, inventory, and other details.

{
  "name": "Bag",
  "model": "bag_01",
  "description": "Product description",
  "price": 99.9,
  "sku": "bag_01",
  "short_description": "Short description. This is very short description",
  "type": "simple",
  "status": "disabled",
  "visible": "search",
  "category_id": "6",
  "categories_ids": "23,56",
  "product_class": "Shirts",
  "product_type": "BICYCLE",
  "is_virtual": false,
  "downloadable": false,
  "is_supply": true,
  "available_for_view": true,
  "available_for_sale": true,
  "store_id": "1",
  "stores_ids": "1,2",
  "lang_id": "3",
  "old_price": 99.9,
  "special_price": 56.9,
  "wholesale_price": 56.12,
  "cost_price": 65.9,
  "fixed_cost_shipping_price": 5.5,
  "tier_prices": [
    {
      "quantity": 0,
      "price": 0
    }
  ],
  "group_prices": [
    {
      "group_id": "string",
      "price": 0,
      "qty": 0
    }
  ],
  "buyitnow_price": 65.9,
  "reserve_price": 65.9,
  "measure_unit": "Piece",
  "unit_price": 10.5,
  "prices_inc_tax": false,
  "retail_price": 6.9,
  "quantity": 0,
  "in_stock": true,
  "manage_stock": false,
  "warehouse_id": "1",
  "backorder_status": "true",
  "min_order_quantity": 1,
  "max_order_quantity": 1,
  "low_stock_threshold": 1,
  "weight": 0,
  "weight_unit": "lb",
  "width": 56.12,
  "height": 56.12,
  "length": 56.12,
  "dimensions_unit": "cm",
  "barcode": "9770317847001",
  "upc": "9770317847001",
  "ean": "5901234123457",
  "isbn": "9783161484100",
  "gtin": "12345678912345",
  "mpn": "9770317847001",
  "asin": "97703178470",
  "product_reference": "5901234123457",
  "external_product_link": "http://example.com/t-shirt",
  "harmonized_system_code": "123456",
  "country_of_origin": "123456",
  "manufacturer": "Samsung",
  "manufacturer_id": "1",
  "manufacturer_info": {
    "name": "string",
    "address": "string",
    "phone": "string",
    "email": "string"
  },
  "brand_name": "Abidas",
  "image_url": "https://docs.api2cart.com/img/logo.png",
  "image_name": "abibas.png",
  "additional_image_urls": [
    "https://example.com/"
  ],
  "files": [
    {
      "name": "string",
      "url": "string"
    }
  ],
  "size_chart": {
    "id": "string",
    "url": "string"
  },
  "related_products_ids": "4,5",
  "up_sell_products_ids": "4,5",
  "cross_sell_products_ids": "4,5",
  "attribute_set_name": "Default",
  "attribute_name": "Color,Manufacturer",
  "search_keywords": "key1,key2,key3",
  "tags": "tag1,tag2",
  "materials": "materials[0]=Aluminum&materials[1]=Brass",
  "certifications": [
    {
      "id": "string",
      "images": [
        {
          "url": "string"
        }
      ],
      "files": [
        {
          "url": "string"
        }
      ]
    }
  ],
  "specifics": [
    {
      "name": "string",
      "value": "string",
      "values": [
        "string"
      ],
      "used_for_variations": false,
      "scale_id": null,
      "input_value": null,
      "food_details": {
        "calories": 0
      },
      "group_products_details": [
        {
          "id": "string",
          "quantity": 1
        }
      ],
      "booking_details": {
        "location": "string",
        "type": "date",
        "session_duration": 0,
        "session_gap": 0,
        "sessions_count": 0,
        "time_strict_value": 0,
        "time_strict_type": "days",
        "availabilities": [
          {
            "day": "sunday",
            "is_available": true,
            "times": [
              {
                "from": "15:46",
                "to": "20:21"
              }
            ]
          }
        ],
        "overrides": [
          {
            "day": "sunday",
            "date": "2069-07-30"
          }
        ]
      }
    }
  ],
  "avail_from": "2029-10-25T15:54:37-0500",
  "sprice_create": "2018-08-25 23:56:12",
  "sprice_modified": "2018-12-05 13:46:20",
  "sprice_expire": "2018-08-25 23:56:12",
  "created_at": "2014-08-09 13:13:13",
  "auto_renew": false,
  "when_made": "made_to_order",
  "meta_title": "category,test",
  "meta_keywords": "category,test",
  "meta_description": "category,test",
  "url": "/product_slug",
  "seo_url": "some seo url",
  "tax_class_id": "9",
  "taxable": true,
  "sales_tax": {
    "tax_percent": 0,
    "tax_state": "string",
    "shipping_inc_in_tax": true
  },
  "condition": "Like New",
  "condition_description": "Almost perfect condition, a few scratches",
  "allow_display_condition": false,
  "payment_methods": "payment_methods[0]=CashOnPickup&payment_methods[1]=PayPal",
  "paypal_email": "[email protected]",
  "shipping_template_id": 0,
  "processing_profile_id": "`12345678`",
  "shipping_details": [
    {
      "shipping_type": "string",
      "shipping_service": "string",
      "shipping_cost": 0
    }
  ],
  "is_free_shipping": true,
  "delivery_code": "24uurs-23",
  "delivery_type": "PARCEL",
  "delivery_time": 1,
  "delivery_option_ids": "6956548250505111111,6956548250505111112",
  "package_details": {
    "measure_unit": "string",
    "weigh_unit": "string",
    "package_depth": 0,
    "package_length": 0,
    "package_width": 0,
    "weight_major": 0,
    "weight_minor": 0,
    "shipping_package": "string"
  },
  "logistic_info": [
    {
      "logistic_id": 0,
      "is_free": true,
      "shipping_fee": 0,
      "size_id": 0
    }
  ],
  "listing_duration": "Days_3",
  "listing_type": "FixedPrice",
  "category_type": "Apparel",
  "return_accepted": true,
  "seller_profiles": {
    "shipping_profile_id": "string",
    "payment_profile_id": "string",
    "return_profile_id": "string"
  },
  "auction_confidentiality_level": "public",
  "best_offer": {
    "minimum_offer_price": 0,
    "auto_accept_price": 0
  },
  "production_partner_ids": "4,5",
  "marketplace_item_properties": "{\"color\":[\"Silver\"],\"manufacturer\":\"Philips\",\"features\":[\"3 way\"],\"countPerPack\":1,\"watts\":{\"unit\":\"W\",\"measure\":40}}",
  "clear_cache": true,
  "viewed_count": 0,
  "ordered_count": 0,
  "vendor_id": "1",
  "shop_section_id": 12345678,
  "return_policy_id": "`12345678`",
  "personalization_details": {
    "is_personalizable": true,
    "personalization_is_required": true,
    "personalization_char_count_max": 0,
    "personalization_instructions": "string"
  },
  "personalization_questions": [
    {
      "question_text": "string",
      "instructions": "string",
      "question_type": "text_input",
      "required": true,
      "max_allowed_characters": 1,
      "max_allowed_files": 1,
      "options": [
        "string"
      ]
    }
  ],
  "manufacturer_ids": "1,2,3",
  "responsible_person_ids": "1,2,3",
  "idempotency_key": "098f6bcd4621d373cade4e832627b4f6"
}

Response Example

After the request is processed successfully, the API returns a response containing the operation status and the identifier of the newly created product. This identifier can then be used for future CRUD operations such as retrieving, updating, or deleting the resource.

{
  "return_code": 0,
  "return_message": "string",
  "result": {
    "product_id": "string"
  }
}

Update a Product (PUT)

The Product Update method illustrates how existing product data can be modified while keeping the same resource available across supported platforms.

Request Example

The request specifies the product identifier together with the fields that should be updated. This allows applications to keep catalog data synchronized without recreating existing products.

{
  "id": "10",
  "model": "bag_01",
  "sku": "bag_01",
  "name": "Pancil",
  "description": "New product description",
  "short_description": "Short description. This is very short description",
  "prices_inc_tax": false,
  "price": 99.9,
  "old_price": 99.9,
  "special_price": 56.9,
  "sprice_create": "2018-08-25 23:56:12",
  "sprice_expire": "2018-08-25 23:56:12",
  "cost_price": 65.9,
  "fixed_cost_shipping_price": 5.5,
  "retail_price": 6.9,
  "tier_prices": [
    {
      "quantity": 0,
      "price": 0
    }
  ],
  "reserve_price": 65.9,
  "buyitnow_price": 65.9,
  "taxable": false,
  "tax_class_id": "9",
  "type": "simple",
  "status": "disabled",
  "condition": "Like New",
  "visible": "search",
  "in_stock": true,
  "avail": true,
  "avail_from": "2029-10-25T15:54:37-0500",
  "product_class": "Shirts",
  "brand_name": "Abidas",
  "available_for_view": false,
  "measure_unit": "Piece",
  "unit_price": 10.5,
  "stores_ids": "1,2",
  "store_id": "1",
  "lang_id": "3",
  "quantity": 6,
  "reserve_quantity": 1,
  "manage_stock": false,
  "backorder_status": "true",
  "increase_quantity": 4,
  "reduce_quantity": 4,
  "low_stock_threshold": 1,
  "min_order_quantity": 1,
  "max_order_quantity": 1,
  "warehouse_id": "1",
  "weight": 23.69,
  "weight_unit": "lb",
  "height": 56.12,
  "length": 56.12,
  "width": 56.12,
  "dimensions_unit": "cm",
  "is_virtual": false,
  "is_free_shipping": true,
  "gtin": "12345678912345",
  "upc": "9770317847001",
  "mpn": "9770317847001",
  "ean": "5901234123457",
  "isbn": "9783161484100",
  "barcode": "9770317847001",
  "manufacturer": "Samsung",
  "manufacturer_id": "1",
  "vendor_id": "1",
  "categories_ids": "23,56",
  "related_products_ids": "4,5",
  "up_sell_products_ids": "4,5",
  "cross_sell_products_ids": "4,5",
  "meta_title": "category,test",
  "meta_keywords": "category,test",
  "meta_description": "category,test",
  "seo_url": "some seo url",
  "search_keywords": "key1,key2,key3",
  "tags": "tag1,tag2",
  "delivery_code": "24uurs-23",
  "package_details": {
    "measure_unit": "string",
    "weigh_unit": "string",
    "package_depth": 0,
    "package_length": 0,
    "package_width": 0,
    "weight_major": 0,
    "weight_minor": 0,
    "shipping_package": "string"
  },
  "country_of_origin": "123456",
  "harmonized_system_code": "123456",
  "shipping_template_id": 0,
  "processing_profile_id": "`12345678`",
  "when_made": "made_to_order",
  "is_supply": true,
  "downloadable": false,
  "materials": "materials[0]=Aluminum&materials[1]=Brass",
  "auto_renew": false,
  "on_sale": false,
  "production_partner_ids": "4,5",
  "manufacturer_info": {
    "name": "string",
    "address": "string",
    "phone": "string",
    "email": "string"
  },
  "report_request_id": "105245017661",
  "disable_report_cache": false,
  "reindex": true,
  "clear_cache": true,
  "check_process_status": false,
  "specifics": [
    {
      "name": "string",
      "value": "string",
      "values": [
        "string"
      ],
      "used_for_variations": false,
      "scale_id": null,
      "input_value": null,
      "food_details": {
        "calories": 0
      },
      "group_products_details": [
        {
          "id": "string",
          "quantity": 1
        }
      ],
      "booking_details": {
        "location": "string",
        "type": "date",
        "session_duration": 0,
        "session_gap": 0,
        "sessions_count": 0,
        "time_strict_value": 0,
        "time_strict_type": "days",
        "availabilities": [
          {
            "day": "sunday",
            "is_available": true,
            "times": [
              {
                "from": "15:47",
                "to": "07:00"
              }
            ]
          }
        ],
        "overrides": [
          {
            "day": "sunday",
            "date": "2024-08-15"
          }
        ]
      }
    }
  ],
  "shop_section_id": 12345678,
  "personalization_details": {
    "is_personalizable": true,
    "personalization_is_required": true,
    "personalization_char_count_max": 0,
    "personalization_instructions": "string"
  },
  "personalization_questions": [
    {
      "question_text": "string",
      "instructions": "string",
      "question_type": "text_input",
      "required": true,
      "max_allowed_characters": 1,
      "max_allowed_files": 1,
      "options": [
        "string"
      ]
    }
  ],
  "external_product_link": "http://example.com/t-shirt",
  "marketplace_item_properties": "{\"color\":[\"Silver\"],\"manufacturer\":\"Philips\",\"features\":[\"3 way\"],\"countPerPack\":1,\"watts\":{\"unit\":\"W\",\"measure\":40}}",
  "manufacturer_ids": "1,2,3",
  "responsible_person_ids": "1,2,3",
  "idempotency_key": "098f6bcd4621d373cade4e832627b4f6"
}

Response Example

Once the update is completed, the API returns a response confirming that the operation was successful. Applications can use this response to verify synchronization and continue processing additional CRUD operations.

{
  "return_code": 0,
  "return_message": "string",
  "result": {
    "updated_items": 0
  }
}

Conclusion

CRUD methods form the foundation of modern REST APIs and enable applications to create, retrieve, update, and delete data efficiently. Understanding when to use GET, POST, PUT, PATCH, and DELETE helps developers build reliable integrations that remain easy to maintain as products evolve.

For software vendors connecting to multiple shopping carts and marketplaces, maintaining separate CRUD implementations quickly becomes expensive. API2Cart eliminates that complexity by providing a single integration for 70+ eCommerce platforms and marketplaces, along with consistent API methods for managing products, orders, customers, shipments, and many other store entities.

Explore the interactive API documentation to see every available endpoint, or Create a Free API2Cart Account and start building your first eCommerce integration with a free trial.