> ## Documentation Index > Fetch the complete documentation index at: https://walletconnect-pay-docs-wcagent-webview-integration-docs.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # WalletConnect Pay SDK - Web/Node.js > Integrate WalletConnect Pay into your Web/Node.js wallet to enable seamless crypto payments for your users. The WalletConnect Pay SDK allows wallet users to pay merchants using their crypto assets. The SDK handles payment option discovery, permit signing coordination, and payment confirmation while leveraging your wallet's existing signing infrastructure. ## Sample Wallet For a complete working example, check out our sample wallet implementation: A reference web wallet app demonstrating WalletConnect Pay integration. ## Requirements * Node.js 16+ ## Installation Install the WalletConnect Pay SDK using npm or yarn: ```bash theme={null} npm install @walletconnect/pay ``` ```bash theme={null} yarn add @walletconnect/pay ``` ## Architecture The SDK uses a provider abstraction that allows different implementations: * **WasmProvider**: Uses WebAssembly module for web browsers * **NativeProvider**: Uses platform-specific uniffi module (for React Native environments) The SDK auto-detects the best available provider for your environment. ## Initialization Initialize the WalletConnect Pay client with your credentials: ```typescript theme={null} import { WalletConnectPay } from "@walletconnect/pay"; const client = new WalletConnectPay({ appId: "your-wcp-id", // OR use apiKey instead: // apiKey: "your-api-key", }); ``` **Configuration Parameters** | Parameter | Type | Required | Description | | ---------- | -------- | -------- | ------------------------------- | | `appId` | `string` | No\* | WCP ID for authentication | | `apiKey` | `string` | No\* | API key for authentication | | `clientId` | `string` | No | Client ID for tracking | | `baseUrl` | `string` | No | Custom API base URL | | `logger` | `Logger` | No | Custom logger instance or level | Either `appId` or `apiKey` must be provided for authentication. Don't have a project ID? Create one at the [WalletConnect Dashboard](https://dashboard.walletconnect.com) by signing up and creating a new project. ## Supported Networks & Tokens WalletConnect Pay currently supports the following tokens and networks: | Token | Network | Chain ID | CAIP-10 Format | | ----- | -------- | -------- | ------------------------ | | USDC | Arbitrum | 42161 | `eip155:42161:{address}` | | USDC | Base | 8453 | `eip155:8453:{address}` | | USDC | Polygon | 137 | `eip155:137:{address}` | | USDC | Ethereum | 1 | `eip155:1:{address}` | | USDC | Optimism | 10 | `eip155:10:{address}` | | USDC | Monad | 143 | `eip155:143:{address}` | | USDC | Celo | 42220 | `eip155:42220:{address}` | | USDC | BSC | 56 | `eip155:56:{address}` | | EURC | Ethereum | 1 | `eip155:1:{address}` | | EURC | Base | 8453 | `eip155:8453:{address}` | | USDT0 | Arbitrum | 42161 | `eip155:42161:{address}` | | PYUSD | Ethereum | 1 | `eip155:1:{address}` | | PYUSD | Arbitrum | 42161 | `eip155:42161:{address}` | | USDG | Ethereum | 1 | `eip155:1:{address}` | | USDT | Ethereum | 1 | `eip155:1:{address}` | | USDT | Polygon | 137 | `eip155:137:{address}` | | USDT | BSC | 56 | `eip155:56:{address}` | Include accounts for all supported networks to maximize payment options for your users. ## Payment Flow The payment flow consists of five main steps: **Get Options -> Collect Data (if required) -> Get Actions -> Sign Actions -> Confirm Payment** ```mermaid theme={null} sequenceDiagram participant User participant Wallet participant PaySDK as Pay SDK participant Backend as WalletConnect Pay participant Iframe User->>Wallet: Scan QR / Open payment link Wallet->>PaySDK: getPaymentOptions(link, accounts) PaySDK->>Backend: Fetch payment options Backend-->>PaySDK: Payment options + merchant info PaySDK-->>Wallet: PaymentOptionsResponse Wallet->>User: Display payment options User->>Wallet: Select payment option alt Selected option requires data collection Wallet->>Iframe: Load selectedOption.collectData.url in iframe Iframe->>User: Display data collection form User->>Iframe: Fill form & accept T&C Iframe-->>Wallet: IC_COMPLETE message via postMessage end Wallet->>PaySDK: getRequiredPaymentActions(paymentId, optionId) PaySDK->>Backend: Get signing actions Backend-->>PaySDK: Required wallet RPC actions PaySDK-->>Wallet: List of actions to sign Wallet->>User: Request signature(s) User->>Wallet: Approve & sign Wallet->>PaySDK: confirmPayment(signatures) PaySDK->>Backend: Submit payment Backend-->>PaySDK: Payment status PaySDK-->>Wallet: ConfirmPaymentResponse Wallet->>User: Show result ``` When a user scans a payment QR code or opens a payment link, fetch available payment options: ```typescript theme={null} const options = await client.getPaymentOptions({ paymentLink: "https://pay.walletconnect.com/pay_123", accounts: [ `eip155:1:${walletAddress}`, // Ethereum Mainnet `eip155:8453:${walletAddress}`, // Base ], includePaymentInfo: true, }); console.log("Payment ID:", options.paymentId); console.log("Options:", options.options); // Display merchant info if (options.info) { console.log("Merchant:", options.info.merchant.name); console.log("Amount:", options.info.amount.display.assetSymbol, options.info.amount.value); } // Check which options require data collection for (const option of options.options) { if (option.collectData) { console.log(`Option ${option.id} requires info capture`); } } ``` After the user selects an option, check for `collectData` on it. If present, collect the data **before** fetching the required actions. ## Embedded Data Collection Form When a payment requires user information (e.g., for Travel Rule compliance), the SDK returns a `collectData` field on individual payment options. Each option may independently require data collection — some options may require it while others don't. The form is loaded from `selectedOption.collectData.url` and embedded in your wallet (a WebView on mobile, an iframe on web). It handles field rendering, validation, Terms & Conditions and Privacy Policy acceptance, and submits data directly to the backend. Collect this data **before** fetching the required actions. For an option that requires Information Capture, `getRequiredPaymentActions` fails with `400 IC data required` until the data has been submitted. ### Recommended Flow The recommended approach is to display all payment options upfront, then handle data collection only when the user selects an option that requires it: 1. Call `getPaymentOptions` and display all available options to the user 2. Show a visual indicator (e.g., "Info required" badge) on options where `option.collectData` is present 3. When the user selects an option, check `selectedOption.collectData` 4. If present, load `selectedOption.collectData.url` in the embedded form 5. Optionally append query parameters to the form URL — `prefill` (known user data), `theme`, and `themeVariables` (appearance). See [Form URL parameters](#form-url-parameters) below. Use proper URL building so existing query parameters are preserved. 6. Listen for completion messages: `IC_COMPLETE` (success) or `IC_ERROR` (failure) 7. On `IC_COMPLETE`, continue the flow — fetch the required actions, sign, and confirm the payment. Don't pass `collectedData` to `confirmPayment()`; the form submits data directly to the backend ### Decision Matrix | Response `collectData` | `option.collectData` | Behavior | | ---------------------- | -------------------- | ------------------------------------------------------------------- | | present | present | Option requires IC — use `option.collectData.url` | | present | `null` | Option does NOT require IC (others might) — skip IC for this option | | `null` | `null` | No IC needed for any option | ### Form URL parameters The form URL accepts the following optional query parameters. Append them to `selectedOption.collectData.url` before loading it, preserving any existing query parameters. | Parameter | Format | Description | | ---------------- | ---------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `prefill` | base64url-encoded JSON | Pre-populates known user fields so the user doesn't re-enter them. Keys must match the `required` fields from `collectData.schema` (e.g. `fullName`, `dob`, `pobAddress`). | | `theme` | `light` or `dark` | Sets the form's base color mode. | | `themeVariables` | base64url-encoded JSON | Overrides design tokens to match your brand — font, font size, select colors, button border radius, and input border radius. Generate and export this value from the [WalletConnect Pay Dashboard](https://dashboard.walletconnect.com). | `collectData.schema` is a JSON schema **string** — parse it and read its `required` array to discover the field keys for `prefill`. For example, a `required` array of `["fullName", "dob", "pobAddress"]` maps to a prefill object of `{"fullName": "...", "dob": "...", "pobAddress": "..."}`. #### Customizing the form appearance `theme` and `themeVariables` are optional and independent — pass either, both, or neither: * **`theme`** switches the form between `light` and `dark` base color modes. Match it to your wallet's active mode for a seamless transition. * **`themeVariables`** applies brand-level overrides (font, font size, select colors, button border radius, and input border radius). Generate the theme in the [WalletConnect Pay Dashboard](https://dashboard.walletconnect.com), export it as a base64url string, and append it to the form URL verbatim — you don't need to encode it at runtime. The top-level `collectData` on the payment options response is still available for backward compatibility. However, the per-option `collectData` is the recommended approach as it provides more granular control over the flow. Do **not** pass `collectedData` to `confirmPayment()` when using the embedded form. The form handles data submission directly. ```typescript theme={null} // Check per-option data collection requirement after user selects an option if (selectedOption.collectData?.url) { // Use the "required" list from selectedOption.collectData.schema to determine which fields to prefill const prefillData = { fullName: "John Doe", dob: "1990-01-15", pobAddress: "123 Main St, New York, NY 10001", }; // Encode prefill as base64url (URL-safe, no padding) const prefill = btoa(JSON.stringify(prefillData)) .replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/, ""); // Optional appearance params (see "Form URL parameters"): // theme=light|dark — base color mode // themeVariables= — exported from the WalletConnect Pay Dashboard const themeVariables = ""; const query = `prefill=${prefill}&theme=dark&themeVariables=${themeVariables}`; const separator = selectedOption.collectData.url.includes("?") ? "&" : "?"; const iframeUrl = `${selectedOption.collectData.url}${separator}${query}`; // Show data collection in an iframe or popup — see Data Collection Implementation section below showDataCollectionView(iframeUrl); } ``` ### Iframe Message Types The iframe communicates with your wallet through `postMessage` events. The message payload is a JSON string with the following structure: | Message Type | Payload | Description | | ------------- | -------------------------------------------- | ------------------------------------------------------------------------- | | `IC_COMPLETE` | `{ "type": "IC_COMPLETE", "success": true }` | User completed the form successfully. Proceed to payment confirmation. | | `IC_ERROR` | `{ "type": "IC_ERROR", "error": "..." }` | An error occurred. Display the error message and allow the user to retry. | After the user selects a payment option, get the wallet RPC actions required to complete the payment: ```typescript theme={null} const actions = await client.getRequiredPaymentActions({ paymentId: options.paymentId, optionId: options.options[0].id, }); // Each action contains wallet RPC data to sign for (const action of actions) { console.log("Chain:", action.walletRpc.chainId); console.log("Method:", action.walletRpc.method); console.log("Params:", action.walletRpc.params); } ``` Sign each action with your wallet's signing implementation: ```typescript theme={null} // Sign each action based on its RPC method const signatures = await Promise.all( actions.map(async (action) => { const { chainId, method, params } = action.walletRpc; const parsedParams = JSON.parse(params); switch (method) { case "eth_signTypedData_v4": return await wallet.signTypedData(chainId, parsedParams); case "eth_sendTransaction": return await wallet.sendTransaction(chainId, parsedParams[0]); case "personal_sign": return await wallet.personalSign(chainId, parsedParams); default: throw new Error(`Unsupported RPC method: ${method}`); } }) ); ``` Payment options may include multiple actions with different RPC methods. For example, a Permit2 payment where the user lacks sufficient allowance returns two actions: an `eth_sendTransaction` to approve the token allowance, followed by an `eth_signTypedData_v4` to sign the Permit2 transfer. Your wallet must check `action.walletRpc.method` and dispatch to the appropriate handler. For full implementation guidance, see [USDT support](/payments/wallets/token-chain-support/usdt-support). Signatures must be in the same order as the actions array. Submit the signatures and collected data to complete the payment: ```typescript theme={null} const result = await client.confirmPayment({ paymentId: options.paymentId, optionId: options.options[0].id, signatures, collectedData, // Include if collectData was present }); if (result.status === "succeeded") { console.log("Payment successful!"); } else if (result.status === "processing") { console.log("Payment is processing..."); } else if (result.status === "failed") { console.log("Payment failed"); } ``` ## Data Collection Implementation When `selectedOption.collectData.url` is present, display the URL in an iframe or modal. Listen for `postMessage` events to handle completion: **Data Collection Best Practices** * **Display prominently**: Show the form full-screen or as a prominent modal so users can interact with it easily * **Loading indicator**: Show a loading indicator while the form loads * **Handle errors**: Listen for `IC_ERROR` messages and display a user-facing error message with an option to retry * **External links**: Open Terms & Conditions and Privacy Policy links in the system browser rather than navigating within the form * **Domain restriction**: Only allow navigation to WalletConnect pay domains and HTTPS URLs * **Back navigation**: Handle back/dismiss gracefully — confirm cancellation with the user before closing the form mid-flow * **Keyboard behavior**: Test that the soft keyboard appears and behaves correctly when users tap on form inputs * **Theme to match your brand**: Pass `theme=light` or `theme=dark` to match your wallet's active color mode, and apply brand tokens with `themeVariables` exported from the [WalletConnect Pay Dashboard](https://dashboard.walletconnect.com). See [Form URL parameters](#form-url-parameters). ```typescript theme={null} function showDataCollectionView(url: string): Promise { // Create a modal/overlay container const overlay = document.createElement("div"); overlay.style.cssText = "position:fixed;top:0;left:0;width:100%;height:100%;background:rgba(0,0,0,0.5);display:flex;align-items:center;justify-content:center;z-index:9999;"; const iframe = document.createElement("iframe"); iframe.src = url; iframe.style.cssText = "width:450px;height:650px;border:none;border-radius:12px;"; overlay.appendChild(iframe); document.body.appendChild(overlay); return new Promise((resolve, reject) => { function handleMessage(event: MessageEvent) { try { const data = typeof event.data === "string" ? JSON.parse(event.data) : event.data; if (data.type === "IC_COMPLETE") { cleanup(); resolve(); } else if (data.type === "IC_ERROR") { cleanup(); reject(new Error(data.error || "Unknown error")); } } catch { // Ignore non-JSON messages } } function cleanup() { window.removeEventListener("message", handleMessage); document.body.removeChild(overlay); } window.addEventListener("message", handleMessage); }); } function buildFormUrl( baseUrl: string, options: { prefill?: Record; theme?: "light" | "dark"; themeVariables?: string; // base64url string exported from the Pay Dashboard } = {} ): string { const params: string[] = []; if (options.prefill && Object.keys(options.prefill).length > 0) { // base64url: URL-safe, no padding const prefill = btoa(JSON.stringify(options.prefill)) .replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/, ""); params.push(`prefill=${prefill}`); } if (options.theme) params.push(`theme=${options.theme}`); if (options.themeVariables) params.push(`themeVariables=${options.themeVariables}`); if (params.length === 0) return baseUrl; const separator = baseUrl.includes("?") ? "&" : "?"; return `${baseUrl}${separator}${params.join("&")}`; } ``` ## Complete Example Here's a complete implementation example: ```typescript theme={null} import { WalletConnectPay, CollectDataFieldResult } from "@walletconnect/pay"; class PaymentManager { private client: WalletConnectPay; constructor() { this.client = new WalletConnectPay({ appId: "your-wcp-id", }); } async processPayment(paymentLink: string, walletAddress: string) { try { // Step 1: Get payment options const options = await this.client.getPaymentOptions({ paymentLink, accounts: [ `eip155:1:${walletAddress}`, `eip155:137:${walletAddress}`, `eip155:8453:${walletAddress}`, ], includePaymentInfo: true, }); if (options.options.length === 0) { throw new Error("No payment options available"); } // Step 2: Let user select an option (simplified - use first option) const selectedOption = options.options[0]; // Step 3: Collect data via iframe if required for selected option. // This must happen BEFORE fetching required actions, otherwise the // backend rejects the fetch for options that require info capture. if (selectedOption.collectData?.url) { // Show iframe and wait for IC_COMPLETE await this.showDataCollectionView(selectedOption.collectData.url); } // Step 4: Get required actions const actions = await this.client.getRequiredPaymentActions({ paymentId: options.paymentId, optionId: selectedOption.id, }); // Step 5: Sign all actions const signatures = await Promise.all( actions.map((action) => this.signAction(action, walletAddress) ) ); // Step 6: Confirm payment const result = await this.client.confirmPayment({ paymentId: options.paymentId, optionId: selectedOption.id, signatures, }); return result; } catch (error) { console.error("Payment failed:", error); throw error; } } private async signAction(action: Action, walletAddress: string): Promise { const { chainId, method, params } = action.walletRpc; const parsedParams = JSON.parse(params); switch (method) { case "eth_signTypedData_v4": return await wallet.signTypedData(chainId, parsedParams); case "eth_sendTransaction": return await wallet.sendTransaction(chainId, parsedParams[0]); case "personal_sign": return await wallet.personalSign(chainId, parsedParams); default: throw new Error(`Unsupported RPC method: ${method}`); } } } ``` ## Provider Utilities The SDK provides utilities for checking provider availability: ```typescript theme={null} import { isProviderAvailable, detectProviderType, } from "@walletconnect/pay"; // Check if any provider is available if (isProviderAvailable()) { // SDK can be used } // Detect which provider type is available const providerType = detectProviderType(); // 'native' | 'wasm' | null ``` ## API Reference **WalletConnectPay** Main client for payment operations. **Constructor** ```typescript theme={null} new WalletConnectPay(options: WalletConnectPayOptions) ``` **Methods** | Method | Description | | ----------------------------------- | ---------------------------------------- | | `getPaymentOptions(params)` | Fetch available payment options | | `getRequiredPaymentActions(params)` | Get signing actions for a payment option | | `confirmPayment(params)` | Confirm and execute the payment | | `static isAvailable()` | Check if a provider is available | **Data Types** **PaymentStatus** ```typescript theme={null} type PaymentStatus = | "requires_action" | "processing" | "succeeded" | "failed" | "expired"; ``` **PayProviderType** ```typescript theme={null} type PayProviderType = "native" | "wasm"; ``` **CollectDataFieldType** ```typescript theme={null} type CollectDataFieldType = "text" | "date"; ``` **Method Parameters** ```typescript theme={null} interface GetPaymentOptionsParams { /** Payment link or ID */ paymentLink: string; /** List of CAIP-10 accounts */ accounts: string[]; /** Whether to include payment info in response */ includePaymentInfo?: boolean; } interface GetRequiredPaymentActionsParams { /** Payment ID */ paymentId: string; /** Option ID */ optionId: string; } interface ConfirmPaymentParams { /** Payment ID */ paymentId: string; /** Option ID */ optionId: string; /** Signatures from wallet RPC calls */ signatures: string[]; } ``` **Response Types** ```typescript theme={null} interface PaymentOptionsResponse { /** Payment ID extracted from the payment link */ paymentId: string; /** Payment information (if includePaymentInfo was true) */ info?: PaymentInfo; /** Available payment options */ options: PaymentOption[]; /** Data collection requirements (if any) */ collectData?: CollectDataAction; /** Transaction result details (present when payment already completed) */ resultInfo?: PaymentResultInfo; } interface PaymentResultInfo { /** Transaction ID */ txId: string; /** Token amount details */ optionAmount: PayAmount; } interface ConfirmPaymentResponse { /** Payment status */ status: PaymentStatus; /** True if the payment is in a final state */ isFinal: boolean; /** Time to poll for payment status, in milliseconds */ pollInMs?: number; } ``` **PaymentOption** ```typescript theme={null} interface PaymentOption { /** ID of the option */ id: string; /** The option's token and amount */ amount: PayAmount; /** Estimated time to complete the option, in seconds */ etaS: number; /** Actions required to complete the option */ actions: Action[]; /** Per-option data collection requirements */ collectData?: CollectDataAction; } ``` **Action** ```typescript theme={null} interface Action { walletRpc: WalletRpcAction; } interface WalletRpcAction { /** Chain ID in CAIP-2 format (e.g., "eip155:8453") */ chainId: string; /** RPC method name (e.g., "eth_signTypedData_v4", "eth_sendTransaction") */ method: string; /** JSON-encoded params array */ params: string; } ``` **Amount Types** ```typescript theme={null} interface PayAmount { /** Currency unit, prefixed with either "iso4217/" or "caip19/" */ unit: string; /** Amount value, in the currency unit's minor units */ value: string; /** Display information for the amount */ display: AmountDisplay; } interface AmountDisplay { /** Ticker/symbol of the asset */ assetSymbol: string; /** Full name of the asset */ assetName: string; /** Number of minor decimals of the asset */ decimals: number; /** URL of the icon of the asset (if token) */ iconUrl?: string; /** Name of the network of the asset (if token) */ networkName?: string; } ``` **Payment Info Types** ```typescript theme={null} interface PaymentInfo { /** Payment status */ status: PaymentStatus; /** Amount to be paid */ amount: PayAmount; /** Payment expiration timestamp, in seconds since epoch */ expiresAt: number; /** Merchant information */ merchant: MerchantInfo; /** Buyer information (present if payment has been submitted) */ buyer?: BuyerInfo; } interface MerchantInfo { /** Merchant name */ name: string; /** Merchant icon URL */ iconUrl?: string; } interface BuyerInfo { /** Account CAIP-10 */ accountCaip10: string; /** Account provider name */ accountProviderName: string; /** Account provider icon URL */ accountProviderIcon?: string; } ``` **Collect Data Types** ```typescript theme={null} interface CollectDataAction { /** URL for data collection (displayed in iframe) */ url: string; /** JSON schema describing required fields */ schema?: string; } ``` ## Error Handling The SDK throws typed errors for different failure scenarios: ```typescript theme={null} import { PayError, PaymentOptionsError, PaymentActionsError, ConfirmPaymentError, } from "@walletconnect/pay"; try { const options = await client.getPaymentOptions({ paymentLink: link, accounts, }); } catch (error) { if (error instanceof PaymentOptionsError) { console.error("Failed to get options:", error.originalMessage); } else if (error instanceof PayError) { console.error("Pay error:", error.code, error.message); } } ``` **Error Types** | Error Class | Description | | --------------------- | -------------------------------------------- | | `PayError` | Base error class for all Pay SDK errors | | `PaymentOptionsError` | Error when fetching payment options | | `PaymentActionsError` | Error when fetching required payment actions | | `ConfirmPaymentError` | Error when confirming payment | **Error Codes** The `PayError` class includes a `code` property with one of the following values: ```typescript theme={null} type PayErrorCode = | "JSON_PARSE" | "JSON_SERIALIZE" | "PAYMENT_OPTIONS" | "PAYMENT_REQUEST" | "CONFIRM_PAYMENT" | "INITIALIZATION_ERROR" | "UNKNOWN"; ``` ## Best Practices 1. **Check Provider Availability**: Always check if a provider is available before using the SDK 2. **Account Format**: Always use CAIP-10 format for accounts: `eip155:{chainId}:{address}` 3. **Multiple Chains**: Provide accounts for all supported chains to maximize payment options 4. **Signature Order**: Maintain the same order of signatures as the actions array 5. **Error Handling**: Always handle errors gracefully and show appropriate user feedback 6. **Loading States**: Show loading indicators during API calls and signing operations 7. **Expiration**: Check `paymentInfo.expiresAt` and warn users if time is running low 8. **User Data**: Only collect data when `collectData` is present on the selected payment option and you don't already have the required user data. If you already have the required data, you can submit this without collecting from the user. You must make sure the user accepts WalletConnect Terms and Conditions and Privacy Policy before submitting user information to WalletConnect. 9. **Data Collection**: When `selectedOption.collectData?.url` is present, display the URL in an iframe or modal rather than building custom forms. The hosted form handles rendering, validation, and T\&C acceptance. 10. **Per-Option Data Collection**: When displaying payment options, check each option's `collectData` field. Show a visual indicator (e.g., "Info required" badge) on options that require data collection. Only open the iframe when the user selects an option with `collectData` present — use the option's `collectData.url` which is already scoped to that option's account.