Square Node.js SDK (square/square-nodejs-sdk)

Square Node.js SDK

https://github.com/square/square-nodejs-sdk
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The Square Node.js SDK provides convenient access to the Square API from TypeScript and JavaScript,...

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# Square Node.js SDK

The Square TypeScript/Node.js SDK provides convenient access to Square's comprehensive commerce APIs from TypeScript and JavaScript applications. It enables developers to integrate Square's payment processing, customer management, inventory tracking, and merchant services into their applications. The SDK is auto-generated using Fern and provides type-safe interfaces for all Square API endpoints, making it easy to build point-of-sale systems, e-commerce platforms, subscription services, and custom business applications.

The SDK follows modern Node.js patterns with full TypeScript support, automatic pagination, webhook signature verification, and built-in retry logic with exponential backoff. It works across multiple JavaScript runtimes including Node.js 18+, Deno, Bun, Vercel, Cloudflare Workers, and React Native. The library handles authentication via bearer tokens, supports request customization through headers and timeouts, and provides comprehensive error handling for all API operations.

## Client Initialization

Initialize the SDK client with an access token

```typescript
import { SquareClient } from "square";

const client = new SquareClient({
    token: "YOUR_ACCESS_TOKEN",
    environment: "production" // or "sandbox" for testing
});

// With custom configuration
const client = new SquareClient({
    token: process.env.SQUARE_ACCESS_TOKEN,
    version: "2025-09-24", // Override API version
    headers: {
        'X-Custom-Header': 'custom value'
    },
    fetcher: customFetchFunction // Custom fetch implementation
});
```

## Create Payment

Process a card payment with amount, customer, and location details

```typescript
import { SquareClient } from "square";

const client = new SquareClient({ token: "YOUR_TOKEN" });

try {
    const result = await client.payments.create({
        sourceId: "ccof:GaJGNaZa8x4OgDJn4GB",
        idempotencyKey: "7b0f3ec5-086a-4871-8f13-3c81b3875218",
        amountMoney: {
            amount: BigInt(1000), // $10.00 in cents
            currency: "USD",
        },
        appFeeMoney: {
            amount: BigInt(10), // Platform fee
            currency: "USD",
        },
        autocomplete: true,
        customerId: "W92WH6P11H4Z77CTET0RNTGFW8",
        locationId: "L88917AVBK2S5",
        referenceId: "123456",
        note: "Brief description",
    });

    console.log("Payment ID:", result.payment?.id);
    console.log("Status:", result.payment?.status);
} catch (err) {
    if (err instanceof SquareError) {
        console.error("Status:", err.statusCode);
        console.error("Message:", err.message);
        console.error("Body:", err.body);
    }
}
```

## List Payments with Pagination

Retrieve a paginated list of payments with automatic iteration

```typescript
import { SquareClient } from "square";

const client = new SquareClient({ token: "YOUR_TOKEN" });

// Automatic iteration through all pages
const response = await client.payments.list({
    locationId: "L88917AVBK2S5",
    beginTime: "2023-01-01T00:00:00Z",
    endTime: "2023-12-31T23:59:59Z"
});

for await (const payment of response) {
    console.log("Payment:", payment.id, payment.amountMoney?.amount);
}

// Manual page-by-page iteration
let page = await client.payments.list();
while (page.hasNextPage()) {
    console.log("Processing page...");
    page = page.getNextPage();
}
```

## Update and Cancel Payment

Modify payment amount or cancel an approved payment

```typescript
// Update payment amount or tip
const updateResult = await client.payments.update({
    paymentId: "payment_id",
    payment: {
        amountMoney: {
            amount: BigInt(1000),
            currency: "USD"
        },
        tipMoney: {
            amount: BigInt(100),
            currency: "USD"
        },
        versionToken: "ODhwVQ35xwlzRuoZEwKXucfu7583sPTzK48c5zoGd0g6o"
    },
    idempotencyKey: "956f8b13-e4ec-45d6-85e8-d1d95ef0c5de"
});

// Cancel a payment
const cancelResult = await client.payments.cancel({
    paymentId: "payment_id"
});

// Complete a payment with delayed capture
const completeResult = await client.payments.complete({
    paymentId: "payment_id"
});
```

## Create Customer

Create a new customer profile with contact and address information

```typescript
const customer = await client.customers.create({
    givenName: "Amelia",
    familyName: "Earhart",
    emailAddress: "Amelia.Earhart@example.com",
    address: {
        addressLine1: "500 Electric Ave",
        addressLine2: "Suite 600",
        locality: "New York",
        administrativeDistrictLevel1: "NY",
        postalCode: "10003",
        country: "US"
    },
    phoneNumber: "+1-212-555-4240",
    referenceId: "YOUR_REFERENCE_ID",
    note: "a customer"
});

console.log("Customer ID:", customer.customer?.id);
console.log("Created at:", customer.customer?.createdAt);
```

## Search Customers

Search for customers with filters, date ranges, and sorting

```typescript
const searchResult = await client.customers.search({
    limit: BigInt(2),
    query: {
        filter: {
            creationSource: {
                values: ["THIRD_PARTY"],
                rule: "INCLUDE"
            },
            createdAt: {
                startAt: "2018-01-01T00:00:00-00:00",
                endAt: "2018-02-01T00:00:00-00:00"
            },
            emailAddress: {
                fuzzy: "example.com"
            },
            groupIds: {
                all: ["545AXB44B4XXWMVQ4W8SBT3HHF"]
            }
        },
        sort: {
            field: "CREATED_AT",
            order: "ASC"
        }
    }
});

for (const customer of searchResult.customers || []) {
    console.log("Customer:", customer.givenName, customer.familyName);
}
```

## Batch Create Customers

Create multiple customer profiles in a single API call

```typescript
const batchResult = await client.customers.batchCreate({
    customers: {
        "8bb76c4f-e35d-4c5b-90de-1194cd9179f0": {
            givenName: "Amelia",
            familyName: "Earhart",
            emailAddress: "Amelia.Earhart@example.com",
            address: {
                addressLine1: "500 Electric Ave",
                addressLine2: "Suite 600",
                locality: "New York",
                administrativeDistrictLevel1: "NY",
                postalCode: "10003",
                country: "US"
            },
            phoneNumber: "+1-212-555-4240",
            referenceId: "YOUR_REFERENCE_ID",
            note: "a customer"
        },
        "d1689f23-b25d-4932-b2f0-aed00f5e2029": {
            givenName: "Marie",
            familyName: "Curie",
            emailAddress: "Marie.Curie@example.com",
            address: {
                addressLine1: "500 Electric Ave",
                addressLine2: "Suite 601",
                locality: "New York",
                administrativeDistrictLevel1: "NY",
                postalCode: "10003",
                country: "US"
            },
            phoneNumber: "+1-212-444-4240",
            referenceId: "YOUR_REFERENCE_ID",
            note: "another customer"
        }
    }
});

console.log("Created customers:", Object.keys(batchResult.results || {}).length);
```

## Add Card on File

Link a payment card to a customer profile for future use

```typescript
const cardResult = await client.customers.cards.create({
    customerId: "W92WH6P11H4Z77CTET0RNTGFW8",
    cardNonce: "cnon:card-nonce-ok",
    billingAddress: {
        addressLine1: "500 Electric Ave",
        addressLine2: "Suite 600",
        locality: "New York",
        administrativeDistrictLevel1: "NY",
        postalCode: "10003",
        country: "US"
    },
    cardholderName: "Amelia Earhart",
    verificationToken: "verification_token"
});

console.log("Card ID:", cardResult.card?.id);
console.log("Last 4:", cardResult.card?.last4);
console.log("Brand:", cardResult.card?.cardBrand);
```

## Create Order

Create a comprehensive order with line items, taxes, and discounts

```typescript
const order = await client.orders.create({
    order: {
        locationId: "057P5VYJ4A5X1",
        referenceId: "my-order-001",
        lineItems: [
            {
                name: "New York Strip Steak",
                quantity: "1",
                basePriceMoney: {
                    amount: BigInt(1599),
                    currency: "USD"
                }
            },
            {
                quantity: "2",
                catalogObjectId: "BEMYCSMIJL46OCDV4KYIKXIB",
                modifiers: [
                    {
                        catalogObjectId: "CHQX7Y4KY6N5KINJKZCFURPZ"
                    }
                ],
                appliedDiscounts: [
                    {
                        discountUid: "one-dollar-off"
                    }
                ]
            }
        ],
        taxes: [
            {
                uid: "state-sales-tax",
                name: "State Sales Tax",
                percentage: "9",
                scope: "ORDER"
            }
        ],
        discounts: [
            {
                uid: "labor-day-sale",
                name: "Labor Day Sale",
                percentage: "5",
                scope: "ORDER"
            },
            {
                uid: "membership-discount",
                catalogObjectId: "DB7L55ZH2BGWI4H23ULIWOQ7",
                scope: "ORDER"
            },
            {
                uid: "one-dollar-off",
                name: "Sale - $1.00 off",
                amountMoney: {
                    amount: BigInt(100),
                    currency: "USD"
                },
                scope: "LINE_ITEM"
            }
        ]
    },
    idempotencyKey: "8193148c-9586-11e6-99f9-28cfe92138cf"
});

console.log("Order ID:", order.order?.id);
console.log("Total:", order.order?.totalMoney?.amount);
```

## Calculate Order

Preview order pricing without creating the order

```typescript
const calculation = await client.orders.calculate({
    order: {
        locationId: "D7AVYMEAPJ3A3",
        lineItems: [
            {
                name: "Item 1",
                quantity: "1",
                basePriceMoney: {
                    amount: BigInt(500),
                    currency: "USD"
                }
            },
            {
                name: "Item 2",
                quantity: "2",
                basePriceMoney: {
                    amount: BigInt(300),
                    currency: "USD"
                }
            }
        ],
        discounts: [
            {
                name: "50% Off",
                percentage: "50",
                scope: "ORDER"
            }
        ]
    }
});

console.log("Subtotal:", calculation.order?.totalMoney?.amount);
console.log("Tax:", calculation.order?.totalTaxMoney?.amount);
console.log("Total:", calculation.order?.totalMoney?.amount);
```

## Search Orders

Search for orders with advanced filters and sorting

```typescript
const searchResult = await client.orders.search({
    locationIds: ["057P5VYJ4A5X1", "18YC4JDH91E1H"],
    query: {
        filter: {
            stateFilter: {
                states: ["COMPLETED"]
            },
            dateTimeFilter: {
                closedAt: {
                    startAt: "2018-03-03T20:00:00+00:00",
                    endAt: "2019-03-04T21:54:45+00:00"
                }
            }
        },
        sort: {
            sortField: "CLOSED_AT",
            sortOrder: "DESC"
        }
    },
    limit: 3,
    returnEntries: true
});

for (const order of searchResult.orders || []) {
    console.log("Order:", order.id, order.totalMoney?.amount);
}
```

## Update Order

Modify an existing open order's line items and properties

```typescript
const updatedOrder = await client.orders.update({
    orderId: "order_id",
    order: {
        locationId: "location_id",
        lineItems: [
            {
                uid: "cookie_uid",
                name: "COOKIE",
                quantity: "2",
                basePriceMoney: {
                    amount: BigInt(200),
                    currency: "USD"
                }
            }
        ],
        version: 1
    },
    fieldsToClear: ["discounts"],
    idempotencyKey: "UNIQUE_STRING"
});

console.log("Updated order:", updatedOrder.order?.id);
console.log("Version:", updatedOrder.order?.version);
```

## Pay Order

Complete an order with one or more payment IDs

```typescript
const payResult = await client.orders.pay({
    orderId: "order_id",
    idempotencyKey: "c043a359-7ad9-4136-82a9-c3f1d66dcbff",
    paymentIds: [
        "EnZdNAlWCmfh6Mt5FMNST1o7taB",
        "0LRiVlbXVwe8ozu4KbZxd12mvaB"
    ]
});

console.log("Order status:", payResult.order?.state);
console.log("Payment IDs:", payResult.order?.tenders?.map(t => t.id));
```

## Batch Upsert Catalog Objects

Create or update multiple catalog items, variations, and modifiers

```typescript
const catalogResult = await client.catalog.batchUpsert({
    idempotencyKey: "789ff020-f723-43a9-b4b5-43b5dc1fa3dc",
    batches: [
        {
            objects: [
                {
                    type: "ITEM",
                    id: "#Coffee",
                    presentAtAllLocations: true,
                    itemData: {
                        name: "Coffee",
                        description: "Premium roast coffee",
                        categoryId: "#Beverages",
                        variations: [
                            {
                                type: "ITEM_VARIATION",
                                id: "#Small",
                                itemVariationData: {
                                    itemId: "#Coffee",
                                    name: "Small",
                                    pricingType: "FIXED_PRICING",
                                    priceMoney: {
                                        amount: BigInt(250),
                                        currency: "USD"
                                    }
                                }
                            }
                        ]
                    }
                },
                {
                    type: "TAX",
                    id: "#SalesTax",
                    presentAtAllLocations: true,
                    taxData: {
                        name: "Sales Tax",
                        calculationPhase: "TAX_SUBTOTAL_PHASE",
                        inclusionType: "ADDITIVE",
                        percentage: "8.5",
                        enabled: true
                    }
                }
            ]
        }
    ]
});

console.log("Upserted objects:", catalogResult.objects?.length);
```

## Search Catalog Objects

Search for catalog items with prefix and custom queries

```typescript
const catalogSearch = await client.catalog.search({
    objectTypes: ["ITEM"],
    query: {
        prefixQuery: {
            attributeName: "name",
            attributePrefix: "tea"
        }
    },
    limit: 100
});

for (const obj of catalogSearch.objects || []) {
    console.log("Item:", obj.itemData?.name);
}
```

## Search Catalog Items

Advanced search with filters for custom attributes and stock levels

```typescript
const itemSearch = await client.catalog.searchItems({
    textFilter: "red",
    categoryIds: ["WINE_CATEGORY_ID"],
    stockLevels: ["OUT", "LOW"],
    enabledLocationIds: ["ATL_LOCATION_ID"],
    limit: 100,
    sortOrder: "ASC",
    productTypes: ["REGULAR"],
    customAttributeFilters: [
        {
            customAttributeDefinitionId: "VEGAN_DEFINITION_ID",
            boolFilter: true
        },
        {
            customAttributeDefinitionId: "BRAND_DEFINITION_ID",
            stringFilter: "Dark Horse"
        },
        {
            key: "VINTAGE",
            numberFilter: {
                min: "2015",
                max: "2020"
            }
        }
    ]
});

console.log("Found items:", itemSearch.items?.length);
```

## Batch Get Catalog Objects

Retrieve multiple catalog objects by ID with related objects

```typescript
const batchGet = await client.catalog.batchGet({
    objectIds: [
        "W62UWFY35CWMYGVWK6TWJDNI",
        "AA27W3M2GGTF3H6AVPNB77CK"
    ],
    includeRelatedObjects: true
});

for (const obj of batchGet.objects || []) {
    console.log("Object:", obj.type, obj.id);
}
```

## List Locations

Retrieve all business locations for the merchant

```typescript
const locations = await client.locations.list();

for (const location of locations.locations || []) {
    console.log("Location:", location.name);
    console.log("Address:", location.address?.addressLine1);
    console.log("Status:", location.status);
}
```

## Create Location

Add a new business location with address and details

```typescript
const newLocation = await client.locations.create({
    location: {
        name: "Midtown",
        address: {
            addressLine1: "1234 Peachtree St. NE",
            locality: "Atlanta",
            administrativeDistrictLevel1: "GA",
            postalCode: "30309"
        },
        description: "Midtown Atlanta store"
    }
});

console.log("Location ID:", newLocation.location?.id);
console.log("Created at:", newLocation.location?.createdAt);
```

## Update Location

Update location business hours and other properties

```typescript
const updatedLocation = await client.locations.update({
    locationId: "location_id",
    location: {
        businessHours: {
            periods: [
                {
                    dayOfWeek: "FRI",
                    startLocalTime: "07:00",
                    endLocalTime: "18:00"
                },
                {
                    dayOfWeek: "SAT",
                    startLocalTime: "07:00",
                    endLocalTime: "18:00"
                },
                {
                    dayOfWeek: "SUN",
                    startLocalTime: "09:00",
                    endLocalTime: "15:00"
                }
            ]
        },
        description: "Midtown Atlanta store - Open weekends"
    }
});

console.log("Updated location:", updatedLocation.location?.name);
```

## Create Subscription

Enroll a customer in a recurring subscription plan

```typescript
const subscription = await client.subscriptions.create({
    idempotencyKey: "8193148c-9586-11e6-99f9-28cfe92138cf",
    locationId: "S8GWD5R9QB376",
    planVariationId: "6JHXF3B2CW3YKHDV4XEM674H",
    customerId: "CHFGVKYY8RSV93M5KCYTG4PN0G",
    startDate: "2023-06-20",
    cardId: "ccof:qy5x8hHGYsgLrp4Q4GB",
    timezone: "America/Los_Angeles",
    source: {
        name: "My Application"
    },
    phases: [
        {
            ordinal: BigInt(0),
            orderTemplateId: "U2NaowWxzXwpsZU697x7ZHOAnCNZY"
        }
    ]
});

console.log("Subscription ID:", subscription.subscription?.id);
console.log("Status:", subscription.subscription?.status);
```

## Create Refund

Issue a refund for a payment

```typescript
const refund = await client.refunds.create({
    idempotencyKey: "a7e36d40-d24b-11e8-b568-0800200c9a66",
    amountMoney: {
        amount: BigInt(100),
        currency: "USD"
    },
    paymentId: "PAYMENT_ID",
    reason: "Customer requested refund"
});

console.log("Refund ID:", refund.refund?.id);
console.log("Status:", refund.refund?.status);
console.log("Amount:", refund.refund?.amountMoney?.amount);
```

## Create Loyalty Account

Create a loyalty account for a customer with phone mapping

```typescript
const loyaltyAccount = await client.loyalty.accounts.create({
    loyaltyAccount: {
        programId: "d619f755-2d17-41f3-990d-c04ecedd64dd",
        mapping: {
            phoneNumber: "+14155551234"
        }
    },
    idempotencyKey: "ec78c477-b1c3-4899-a209-a4e71337c996"
});

console.log("Account ID:", loyaltyAccount.loyaltyAccount?.id);
console.log("Balance:", loyaltyAccount.loyaltyAccount?.balance);
```

## Create Loyalty Reward

Create a reward for redemption from loyalty points

```typescript
const reward = await client.loyalty.rewards.create({
    reward: {
        loyaltyAccountId: "5adcb100-07f1-4ee7-b8c6-6bb9ebc474bd",
        rewardTierId: "e1b39225-9da5-43d1-a5db-782cdd8ad94f",
        orderId: "RFZfrdtm3mhO1oGzf5Cx7fEMsmGZY"
    },
    idempotencyKey: "18c2e5ea-a620-4b1f-ad60-7b167285e451"
});

console.log("Reward ID:", reward.reward?.id);
console.log("Points:", reward.reward?.points);
```

## Search Loyalty Events

Search for loyalty program events with filters

```typescript
const events = await client.loyalty.searchEvents({
    query: {
        filter: {
            orderFilter: {
                orderId: "PyATxhYLfsMqpVkcKJITPydgEYfZY"
            }
        }
    },
    limit: 30
});

for (const event of events.events || []) {
    console.log("Event:", event.type, event.createdAt);
}
```

## List Invoices

Retrieve invoices for a specific location with pagination

```typescript
const invoicesResponse = await client.invoices.list({
    locationId: "location_id"
});

for await (const invoice of invoicesResponse) {
    console.log("Invoice:", invoice.invoiceNumber);
    console.log("Status:", invoice.status);
    console.log("Amount:", invoice.primaryRecipient?.emailAddress);
}
```

## Verify Webhook Signature

Verify that webhook events originate from Square

```typescript
import { WebhooksHelper } from "square";

// In your webhook endpoint handler
app.post("/webhook", (req, res) => {
    const signatureHeader = req.headers['x-square-hmacsha256-signature'];
    const requestBody = JSON.stringify(req.body);

    const isValid = WebhooksHelper.verifySignature({
        requestBody: requestBody,
        signatureHeader: signatureHeader,
        signatureKey: "YOUR_SIGNATURE_KEY",
        notificationUrl: "https://example.com/webhook"
    });

    if (!isValid) {
        return res.status(403).send("Invalid signature");
    }

    // Process webhook event
    const event = req.body;
    console.log("Event type:", event.type);
    console.log("Event data:", event.data);

    res.status(200).send("OK");
});
```

## Error Handling

Handle API errors with typed exception classes

```typescript
import { SquareClient, SquareError } from "square";

const client = new SquareClient({ token: "YOUR_TOKEN" });

try {
    const payment = await client.payments.create({
        sourceId: "ccof:invalid",
        idempotencyKey: "unique-key",
        amountMoney: {
            amount: BigInt(100),
            currency: "USD"
        }
    });
} catch (err) {
    if (err instanceof SquareError) {
        console.error("HTTP Status:", err.statusCode);
        console.error("Error message:", err.message);
        console.error("Error body:", err.body);
        console.error("Errors:", err.body?.errors);
    } else {
        console.error("Unexpected error:", err);
    }
}
```

## Request Options

Customize requests with timeouts, retries, and custom headers

```typescript
// Override timeout for specific request
const response = await client.payments.create(
    {
        sourceId: "ccof:GaJGNaZa8x4OgDJn4GB",
        idempotencyKey: "unique-key",
        amountMoney: {
            amount: BigInt(1000),
            currency: "USD"
        }
    },
    {
        timeoutInSeconds: 30,
        maxRetries: 3,
        version: "2024-05-04",
        headers: {
            'X-Custom-Header': 'custom-value'
        }
    }
);

// Abort request with AbortController
const controller = new AbortController();
setTimeout(() => controller.abort(), 5000);

const payment = await client.payments.create(
    {
        sourceId: "ccof:GaJGNaZa8x4OgDJn4GB",
        idempotencyKey: "unique-key",
        amountMoney: {
            amount: BigInt(1000),
            currency: "USD"
        }
    },
    {
        abortSignal: controller.signal
    }
);
```

## Type Definitions

Import and use Square type definitions

```typescript
import { Square } from "square";

const createPaymentRequest: Square.CreatePaymentRequest = {
    sourceId: "ccof:GaJGNaZa8x4OgDJn4GB",
    idempotencyKey: "unique-key",
    amountMoney: {
        amount: BigInt(1000),
        currency: "USD"
    }
};

const payment: Square.Payment = {
    id: "payment_id",
    status: "COMPLETED",
    amountMoney: {
        amount: BigInt(1000),
        currency: "USD"
    }
};

// Type-safe customer object
const customer: Square.Customer = {
    id: "customer_id",
    givenName: "John",
    familyName: "Doe",
    emailAddress: "john.doe@example.com",
    createdAt: "2023-01-01T00:00:00Z"
};
```

## Legacy SDK Compatibility

Use both new and legacy SDK APIs in the same application

```typescript
import { randomUUID } from "crypto";
import { Square, SquareClient } from "square";
import { Client } from "square/legacy";

// New SDK client
const client = new SquareClient({
    token: process.env.SQUARE_ACCESS_TOKEN
});

// Legacy SDK client
const legacyClient = new Client({
    bearerAuthCredentials: {
        accessToken: process.env.SQUARE_ACCESS_TOKEN!
    }
});

// Use new SDK for simple operations
async function getLocation(): Promise<Square.Location> {
    return (
        await client.locations.get({
            locationId: "YOUR_LOCATION_ID"
        })
    ).location!;
}

// Use legacy SDK for operations not yet migrated
async function createOrder() {
    const location = await getLocation();
    await legacyClient.ordersApi.createOrder({
        idempotencyKey: randomUUID(),
        order: {
            locationId: location.id!,
            lineItems: [
                {
                    name: "New Item",
                    quantity: "1",
                    basePriceMoney: {
                        amount: BigInt(100),
                        currency: "USD"
                    }
                }
            ]
        }
    });
}

createOrder();
```

---

The Square SDK enables a wide range of commerce integration patterns for modern applications. For e-commerce platforms, developers can create complete checkout flows by combining the Orders API with the Payments API - first creating an order with line items, taxes, and discounts, then processing payment against that order, and finally handling fulfillment. The SDK's built-in pagination support makes it easy to build customer dashboards that display order history, payment records, and subscription status. The idempotency keys ensure that network retries don't result in duplicate charges, which is critical for production payment systems.

For point-of-sale and retail applications, the SDK provides comprehensive inventory management through the Catalog and Inventory APIs. Merchants can maintain product catalogs with variations, modifiers, and images, track stock levels across multiple locations, and sync inventory changes in real-time. The Locations API allows multi-location businesses to manage separate configurations for each store while maintaining centralized customer and loyalty data. The Customers API with card-on-file support enables fast checkout experiences, while the Loyalty API helps merchants build retention programs with points, rewards, and promotions. The webhook signature verification utilities ensure secure handling of asynchronous events like payment status updates, order fulfillment notifications, and inventory alerts. With support for subscriptions, recurring billing, and custom attributes, the SDK provides the building blocks for sophisticated commerce applications across retail, hospitality, services, and digital goods sectors.