TransFi SDK Documentation

Programmatically create and manage payment invoices using the TransFi Checkout API. SDKs are available for Node.js and Python.

Prerequisites

Before using any SDK, you need:

A TransFi merchant account — Sign up here
Your Public Key and Secret Key from the TransFi dashboard
A Payment Link ID — create one in the TransFi dashboard before making API calls

Security notice: Never hardcode your Public Key or Secret Key in source code. Always store them in environment variables.

Installation

npm install transfi-checkout

pip install transfi-sdk

Maven/Gradle via JitPack (com.github.Trans-Fi:transfi-checkout-java-sdk:v1.0.0)

composer require transfi/payment-sdk

Authentication

Both SDKs use HMAC-based authentication built in automatically — you only need to pass your keys when initializing the client.

const { TransFiPaymentAPI } = require("transfi-checkout");

const client = new TransFiPaymentAPI({
  publicKey: process.env.TRANSFI_PUBLIC_KEY,
  secretKey: process.env.TRANSFI_SECRET_KEY,
});

from transfi import TransFiPaymentAPI

api = TransFiPaymentAPI(
    public_key="YOUR_PUBLIC_KEY",
    secret_key="YOUR_SECRET_KEY",
)

sdkConfig config = new sdkConfig("YOUR_PUBLIC_KEY", "YOUR_SECRET_KEY");
transfiPaymentApi api = new transfiPaymentApi(config);

use TransFi\TransFiPaymentAPI;
use TransFi\TransFiError;
use TransFi\PaymentInvoiceRequest;
use TransFi\Individual;
use TransFi\ProductDetails;

$api = new TransFiPaymentAPI([
    'publicKey' => 'YOUR_PUBLIC_KEY',
    'secretKey' => 'YOUR_SECRET_KEY',
]);

Parameter	Type	Required	Description
`publicKey` / `public_key`	string	Yes	Your TransFi API public key
`secretKey` / `secret_key`	string	Yes	Your TransFi API secret key

Quick Start

const { TransFiPaymentAPI } = require("transfi-checkout");

const client = new TransFiPaymentAPI({
  publicKey: process.env.TRANSFI_PUBLIC_KEY,
  secretKey: process.env.TRANSFI_SECRET_KEY,
});

client
  .createPaymentInvoice({
    paymentLinkId: "your-payment-link-id",
    amount: "100",
    currency: "USD",
    productDetails: {
      name: "Premium Annual Plan",
      description: "12-month access to all premium features",
      imageUrl: "https://example.com/product-image.png",
    },
    successRedirectUrl: "https://yourapp.com/payment/success",
    failureRedirectUrl: "https://yourapp.com/payment/failure",
  })
  .then((paymentUrl) => {
    console.log("Redirect customer to:", paymentUrl);
  })
  .catch((error) => {
    console.error("Error:", error.message);
  });

from transfi import TransFiPaymentAPI, TransFiError
from transfi.types import PaymentInvoiceRequest, ProductDetails

api = TransFiPaymentAPI(
    public_key="YOUR_PUBLIC_KEY",
    secret_key="YOUR_SECRET_KEY",
)

request = PaymentInvoiceRequest(
    payment_link_id="your-payment-link-id",
    amount="100",
    currency="USD",
    product_details=ProductDetails(
        name="Premium Annual Plan",
        description="12-month access to all premium features",
        image_url="https://example.com/product-image.png",
    ),
    success_redirect_url="https://yourapp.com/payment/success",
    failure_redirect_url="https://yourapp.com/payment/failure",
)

try:
    payment_url = api.create_payment_invoice(request)
    print("Redirect customer to:", payment_url)
except TransFiError as e:
    print("Error:", e)

paymentInvoiceRequest request = paymentInvoiceRequest.builder()
    .paymentLinkId("YOUR_PAYMENT_LINK_ID")
    .amount("100.00")
    .currency("USD")
    .productDetails(productDetails.builder()
        .name("Premium Subscription")
        .description("Monthly subscription plan")
        .build())
    .individual(individual.builder()
        .firstName("John")
        .lastName("Doe")
        .email("[email protected]")
        .phone("1234567890")
        .phoneCode("+1")
        .country("US")
        .build())
    .successRedirectUrl("https://yoursite.com/success")
    .failureRedirectUrl("https://yoursite.com/failure")
    .customerOrderId("order-" + System.currentTimeMillis())
    .build();

try {
    String paymentUrl = api.createPaymentInvoice(request);
    System.out.println("Payment URL: " + paymentUrl);
    // Redirect user to paymentUrl to complete payment
} catch (transfiError e) {
    System.err.println("Error: " + e.getMessage());
    System.err.println("Status Code: " + e.getStatusCode());
    System.err.println("Response: " + e.getResponseData());
}


use TransFi\TransFiPaymentAPI;
use TransFi\TransFiError;
use TransFi\PaymentInvoiceRequest;
use TransFi\Individual;
use TransFi\ProductDetails;

$api = new TransFiPaymentAPI([
    'publicKey' => 'YOUR_PUBLIC_KEY',
    'secretKey' => 'YOUR_SECRET_KEY',
]);

$product = new ProductDetails('Premium Plan');
$product->description = 'Monthly subscription';

$individual = new Individual('John', 'Doe', '[email protected]');
$individual->phone     = '1234567890';
$individual->phoneCode = '+1';
$individual->country   = 'US';

$paymentData = new PaymentInvoiceRequest(
    'LINK_ID',
    '100',
    'USD',
    'https://example.com/success',
    'https://example.com/failure'
);
$paymentData->productDetails  = $product;
$paymentData->individual      = $individual;
$paymentData->customerOrderId = 'order-001';

try {
    $paymentUrl = $api->createPaymentInvoice($paymentData);
    echo 'Checkout URL: ' . $paymentUrl . PHP_EOL;
} catch (TransFiError $e) {
    echo 'API Error   : ' . $e->getMessage() . PHP_EOL;
    echo 'Status Code : ' . $e->getStatusCode() . PHP_EOL;
    echo 'Response    : ' . json_encode($e->getResponseData(), JSON_PRETTY_PRINT) . PHP_EOL;
}

Methods

`createPaymentInvoice` / `create_payment_invoice`

Creates a payment invoice for a customer and returns a payment URL to redirect the customer to complete the payment.

const paymentUrl = await client.createPaymentInvoice(paymentData);
// Returns: Promise<string> — the checkout URL

payment_url = api.create_payment_invoice(request)
# Returns: str — the checkout URL

String paymentUrl = api.createPaymentInvoice(request);
//// Returns: String — the checkout URL

    $paymentUrl = $api->createPaymentInvoice($paymentData);
    echo 'Checkout URL: ' . $paymentUrl . PHP_EOL;

Parameters

Payment Invoice Request

{
  paymentLinkId: "string",        // Required
  amount: "string",               // Required — e.g. "100" or "49.99"
  currency: "string",             // Required — ISO 4217, e.g. "USD"
  successRedirectUrl: "string",   // Required
  failureRedirectUrl: "string",   // Required
  productDetails: { ... },        // Optional — see below
  individual: { ... },            // Optional — see below
  customerOrderId: "string",      // Optional — your internal order ID
}

PaymentInvoiceRequest(
    payment_link_id="string",         # Required
    amount="string",                  # Required — e.g. "100" or "49.99"
    currency="string",                # Required — ISO 4217, e.g. "USD"
    success_redirect_url="string",    # Required
    failure_redirect_url="string",    # Required
    product_details=ProductDetails(), # Optional — see below
    individual=Individual(),          # Optional — see below
    customer_order_id="string",       # Optional — your internal order ID
)

//Builder pattern for creating payment requests:

paymentInvoiceRequest.builder()
    .paymentLinkId(String)           // Required: Payment link identifier
    .amount(String)                  // Required: Payment amount
    .currency(String)                // Required: Currency code (USD, EUR, etc.)
    .productDetails(productDetails)  // Optional — see below
    .individual(individual)          // Optional — see below
    .successRedirectUrl(String)      // Required: Success redirect URL
    .failureRedirectUrl(String)      // Required: Failure redirect URL
    .customerOrderId(String)         // Optional — see below
     .build();


$paymentData = new PaymentInvoiceRequest(
    'LINK_ID',
    '100',
    'USD',
    'https://example.com/success',
    'https://example.com/failure'
);
$paymentData->productDetails  = $product;
$paymentData->individual      = $individual;
$paymentData->customerOrderId = 'order-001';

Parameter	Node.js key	Python key	PHP Key	Java Key	Type	Required	Description
Payment Link ID	`paymentLinkId`	`payment_link_id`	`paymentLinkId`	`paymentLinkId`	string	Yes	The Payment Link ID from your TransFi dashboard
Amount	`amount`	`amount`	`amount`	`amount`	string	Yes	Amount to charge, e.g. `"100"` or `"49.99"`
Currency	`currency`	`currency`	`currency`	`currency`	string	Yes	ISO 4217 code, e.g. `"USD"`, `"EUR"`, `"SGD"`
Success URL	`successRedirectUrl`	`success_redirect_url`	`successRedirectUrl`	`successRedirectUrl`	string	Yes	Redirect URL after successful payment
Failure URL	`failureRedirectUrl`	`failure_redirect_url`	`failureRedirectUrl`	`failureRedirectUrl`	string	Yes	Redirect URL after failed payment
Product Details	`productDetails`	`product_details`	`productDetails`	`productDetails`	object	No	Product info shown at checkout
Customer	`individual`	`individual`	`individual`	`individual`	object	No	Customer details for pre-fill / KYC
Order ID	`customerOrderId`	`customer_order_id`	`customerOrderId`	`customerOrderId`	string	No	Your internal order reference ID

`productDetails` / `ProductDetails`

Product information displayed on the checkout page.

Field	Node.js key	Python key	Required	Description
Name	`name`	`name`	Yes	Name of the product or service
Description	`description`	`description`	No	Short description of the product
Image URL	`imageUrl`	`image_url`	No	URL of a product image

productDetails: {
  name: "Premium Annual Plan",
  description: "12-month access to all features",
  imageUrl: "https://example.com/product.png",
}

from transfi.types import ProductDetails

ProductDetails(
    name="Premium Annual Plan",
    description="12-month access to all features",
    image_url="https://example.com/product.png",
)

productDetails(productDetails.builder()
        .name("Premium Subscription")
        .description("Monthly subscription plan")
        .build())

'productDetails'     => [
        'name'        => 'Premium Plan',
        'description' => 'Monthly subscription',
    ]

`individual` / `Individual`

Customer information used to pre-fill the checkout form or speed up KYC verification.

Field	Node.js key	Python key	Required	Description
First name	`firstName`	`first_name`	Yes	Customer's first name
Last name	`lastName`	`last_name`	Yes	Customer's last name
Email	`email`	`email`	Yes	Customer's email address
Phone	`phone`	`phone`	No	Phone number without country code
Phone code	`phoneCode`	`phone_code`	No	Dialing code, e.g. `"+1"`, `"+91"`
Country	`country`	`country`	No	ISO 3166-1 alpha-3 (Node.js: `"USA"`) or alpha-2 (Python: `"US"`)
Address	`address`	`address`	No	Customer's address (see below)

individual: {
  firstName: "Jane",
  lastName: "Smith",
  email: "[email protected]",
  phone: "9876543210",
  phoneCode: "+1",
  country: "USA",
  address: {
    street: "123 Main St",
    city: "New York",
    state: "NY",
    postalCode: "10001",
  },
}

from transfi.types import Individual, Address

Individual(
    first_name="Jane",
    last_name="Smith",
    email="[email protected]",
    phone="9876543210",
    phone_code="+1",
    country="US",
    address=Address(
        street="123 Main St",
        city="New York",
        state="NY",
        postal_code="10001",
    ),
)

individual(individual.builder()
        .firstName("John")
        .lastName("Doe")
        .email("[email protected]")
        .phone("1234567890")
        .phoneCode("+1")
        .country("US")
        .build())

'individual'         => [
        'firstName' => 'John',
        'lastName'  => 'Doe',
        'email'     => '[email protected]',
        'phone'     => '1234567890',
        'phoneCode' => '+1',
        'country'   => 'US',
    ]

`address` / `Address`

Field	Node.js key	Python key	Description
Street	`street`	`street`	Street address
City	`city`	`city`	City name
State	`state`	`state`	State or province
Postal code	`postalCode`	`postal_code`	ZIP or postal code

Error Handling

Both SDKs throw a TransFiError when an API call fails.

Property	Node.js	Python	Type	Description
Message	`error.message`	`str(e)`	string	Human-readable error message
Status code	`error.statusCode`	`e.status_code`	number	HTTP status code, e.g. `400`, `401`, `500`
Response body	`error.responseData`	`e.response_data`	any	Raw JSON response from the API

const { TransFiPaymentAPI, TransFiError } = require("transfi-checkout");

try {
  const paymentUrl = await client.createPaymentInvoice({ ... });
} catch (error) {
  if (error instanceof TransFiError) {
    console.error("TransFi API Error:", error.message);
    console.error("HTTP Status:", error.statusCode);   // e.g. 401, 400
    console.error("API Response:", error.responseData); // full error body
  } else {
    // Network error, timeout, etc.
    console.error("Unexpected error:", error.message);
  }
}

from transfi import TransFiPaymentAPI, TransFiError

try:
    payment_url = api.create_payment_invoice(request)
except TransFiError as e:
    print("API Error:   ", e)
    print("Status Code: ", e.status_code)
    print("Response:    ", e.response_data)
except Exception as e:
    # Network error, timeout, etc.
    print("Unexpected error:", e)

try {
    String paymentUrl = api.createPaymentInvoice(request);
    System.out.println("Payment URL: " + paymentUrl);
    // Redirect user to paymentUrl to complete payment
} catch (transfiError e) {
    System.err.println("Error: " + e.getMessage());
    System.err.println("Status Code: " + e.getStatusCode());
    System.err.println("Response: " + e.getResponseData());
}

try {
    $paymentUrl = $api->createPaymentInvoice($paymentData);
    echo 'Checkout URL: ' . $paymentUrl . PHP_EOL;
} catch (TransFiError $e) {
    echo 'API Error   : ' . $e->getMessage() . PHP_EOL;
    echo 'Status Code : ' . $e->getStatusCode() . PHP_EOL;
    echo 'Response    : ' . json_encode($e->getResponseData(), JSON_PRETTY_PRINT) . PHP_EOL;
}

Common HTTP status codes

Status	Meaning	Common cause
`400`	Bad Request	Missing required fields or invalid parameter values
`401`	Unauthorized	Invalid or missing API keys
`404`	Not Found	`paymentLinkId` does not exist in your account
`500`	Server Error	Temporary TransFi API issue — retry with backoff

Full Example

const { TransFiPaymentAPI, TransFiError } = require("transfi-checkout");

const client = new TransFiPaymentAPI({
  publicKey: process.env.TRANSFI_PUBLIC_KEY,
  secretKey: process.env.TRANSFI_SECRET_KEY,
});

async function createInvoice() {
  try {
    const paymentUrl = await client.createPaymentInvoice({
      paymentLinkId: "your-payment-link-id",
      amount: "149.99",
      currency: "USD",
      customerOrderId: "order-" + Date.now(),
      productDetails: {
        name: "Premium Annual Plan",
        description: "12-month access to all premium features",
        imageUrl: "https://example.com/product-image.png",
      },
      individual: {
        firstName: "Jane",
        lastName: "Smith",
        email: "[email protected]",
        phone: "9876543210",
        phoneCode: "+1",
        country: "USA",
        address: {
          street: "123 Main St",
          city: "New York",
          state: "NY",
          postalCode: "10001",
        },
      },
      successRedirectUrl: "https://yourapp.com/payment/success",
      failureRedirectUrl: "https://yourapp.com/payment/failure",
    });

    console.log("Invoice created! Redirect user to:");
    console.log(paymentUrl);
  } catch (error) {
    if (error instanceof TransFiError) {
      console.error(`API Error [${error.statusCode}]: ${error.message}`);
      console.error("Details:", error.responseData);
    } else {
      console.error("Network or unexpected error:", error.message);
    }
  }
}

createInvoice();

from transfi import TransFiPaymentAPI, TransFiError
from transfi.types import PaymentInvoiceRequest, Individual, ProductDetails, Address
import time

api = TransFiPaymentAPI(
    public_key="YOUR_PUBLIC_KEY",
    secret_key="YOUR_SECRET_KEY",
)

request = PaymentInvoiceRequest(
    payment_link_id="your-payment-link-id",
    amount="149.99",
    currency="USD",
    customer_order_id=f"order-{int(time.time())}",
    product_details=ProductDetails(
        name="Premium Annual Plan",
        description="12-month access to all premium features",
        image_url="https://example.com/product-image.png",
    ),
    individual=Individual(
        first_name="Jane",
        last_name="Smith",
        email="[email protected]",
        phone="9876543210",
        phone_code="+1",
        country="US",
        address=Address(
            street="123 Main St",
            city="New York",
            state="NY",
            postal_code="10001",
        ),
    ),
    success_redirect_url="https://yourapp.com/payment/success",
    failure_redirect_url="https://yourapp.com/payment/failure",
)

try:
    payment_url = api.create_payment_invoice(request)
    print("Invoice created! Redirect user to:")
    print(payment_url)
except TransFiError as e:
    print(f"API Error [{e.status_code}]: {e}")
    print("Details:", e.response_data)
except Exception as e:
    print("Network or unexpected error:", e)

paymentInvoiceRequest request = paymentInvoiceRequest.builder()
    .paymentLinkId("YOUR_PAYMENT_LINK_ID")
    .amount("100.00")
    .currency("USD")
    .productDetails(productDetails.builder()
        .name("Premium Subscription")
        .description("Monthly subscription plan")
        .build())
    .individual(individual.builder()
        .firstName("John")
        .lastName("Doe")
        .email("[email protected]")
        .phone("1234567890")
        .phoneCode("+1")
        .country("US")
        .build())
    .successRedirectUrl("https://yoursite.com/success")
    .failureRedirectUrl("https://yoursite.com/failure")
    .customerOrderId("order-" + System.currentTimeMillis())
    .build();

try {
    String paymentUrl = api.createPaymentInvoice(request);
    System.out.println("Payment URL: " + paymentUrl);
    // Redirect user to paymentUrl to complete payment
} catch (transfiError e) {
    System.err.println("Error: " + e.getMessage());
    System.err.println("Status Code: " + e.getStatusCode());
    System.err.println("Response: " + e.getResponseData());
}

$api = new TransFiPaymentAPI([
    'publicKey' => 'YOUR_PUBLIC_KEY',
    'secretKey' => 'YOUR_SECRET_KEY',
]);

$product = new ProductDetails('Premium Plan');
$product->description = 'Monthly subscription';

$individual = new Individual('John', 'Doe', '[email protected]');
$individual->phone     = '1234567890';
$individual->phoneCode = '+1';
$individual->country   = 'US';

$paymentData = new PaymentInvoiceRequest(
    'LINK_ID',
    '100',
    'USD',
    'https://example.com/success',
    'https://example.com/failure'
);
$paymentData->productDetails  = $product;
$paymentData->individual      = $individual;
$paymentData->customerOrderId = 'order-001';

try {
    $paymentUrl = $api->createPaymentInvoice($paymentData);
    echo 'Checkout URL: ' . $paymentUrl . PHP_EOL;
} catch (TransFiError $e) {
    echo 'API Error   : ' . $e->getMessage() . PHP_EOL;
    echo 'Status Code : ' . $e->getStatusCode() . PHP_EOL;
    echo 'Response    : ' . json_encode($e->getResponseData(), JSON_PRETTY_PRINT) . PHP_EOL;
}

Python: Alternative dict syntax

The Python SDK also accepts a plain dict with camelCase keys matching the JSON API directly, if you prefer not to use the dataclasses:

payment_url = api.create_payment_invoice({
    "paymentLinkId": "your-payment-link-id",
    "amount": "100",
    "currency": "USD",
    "productDetails": {
        "name": "Premium Plan",
        "description": "Monthly subscription",
    },
    "individual": {
        "firstName": "John",
        "lastName": "Doe",
        "email": "[email protected]",
        "phone": "1234567890",
        "phoneCode": "+1",
        "country": "US",
    },
    "successRedirectUrl": "https://example.com/success",
    "failureRedirectUrl": "https://example.com/failure",
    "customerOrderId": "order-001",
})

Python: Context manager

The Python client supports the context manager protocol, which ensures the underlying HTTP session is properly closed:

with TransFiPaymentAPI(public_key="...", secret_key="...") as api:
    payment_url = api.create_payment_invoice(request)
    print(payment_url)

SDK Reference Summary

	Node.js (`transfi-checkout`)	Java(`transfi-checkout`)	Python (`transfi-sdk`)	PHP (transfi/payment-sdk)
Install	`npm install transfi-checkout`	`Maven/Gradle via JitPack (com.github.Trans-Fi:transfi-checkout-java-sdk:v1.0.0)`	`pip install transfi-sdk`	`composer require transfi/payment-sdk`
Import	`require("transfi-checkout")`	`No explicit import needed (classes used directly)`	`from transfi import ...`	`use TransFi\TransFiPaymentAPI`
Client class	`TransFiPaymentAPI`	`transfiPaymentApi`	`TransFiPaymentAPI`	`TransFiPaymentAPI`
Create invoice	`client.createPaymentInvoice(data)`	`api.createPaymentInvoice(request)`	`api.create_payment_invoice(data)`	`$api->createPaymentInvoice($data)`
Error class	`TransFiError`	`transfiError`	`TransFiError`	`TransFiError`
Status code	`error.statusCode`	`e.getStatusCode()`	`e.status_code`	`$e->getStatusCode()`
Response body	`error.responseData`	`e.getResponseData()`	`e.response_data`	`$e->getResponseData()`
Context manager	No	`No`	Yes (`with` statement)	`No`
Dict input	Yes (camelCase keys)	`No (Builder pattern)`	Yes (camelCase keys)	`Yes (plain array, camelCase keys)`
Typed input	No	`Yes (paymentInvoiceRequest, productDetails, individual builders)`	Yes (`PaymentInvoiceRequest`, etc.)	`Yes (PaymentInvoiceRequest, Individual, ProductDetails, Address)`