pay-js

Nkwa Pay SDK for Javascript

Summary

Nkwa Pay API: Use this API to integrate mobile money across your payment flows, create and manage payments, collections, and disbursements.

Read the docs at https://docs.mynkwa.com/api-reference

Table of Contents

• pay-js
  • SDK Installation
  • Requirements
  • SDK Example Usage
  • Authentication
  • Available Resources and Operations
  • Standalone functions
  • Retries
  • Error Handling
  • Server Selection
  • Custom HTTP Client
  • Debugging

SDK Installation

The SDK can be installed with either npm, pnpm, bun or yarn package managers.

NPM

npm add @nkwa-pay/sdk

PNPM

pnpm add @nkwa-pay/sdk

Bun

bun add @nkwa-pay/sdk

Yarn

yarn add @nkwa-pay/sdk zod

# Note that Yarn does not install peer dependencies automatically. You will need
# to install zod as shown above.

[!NOTE] This package is published with CommonJS and ES Modules (ESM) support.

Model Context Protocol (MCP) Server

This SDK is also an installable MCP server where the various SDK methods are exposed as tools that can be invoked by AI applications.

Node.js v20 or greater is required to run the MCP server from npm.

Add the following server definition to your claude_desktop_config.json file:

{
  "mcpServers": {
    "Pay": {
      "command": "npx",
      "args": [
        "-y", "--package", "@nkwa-pay/sdk",
        "--",
        "mcp", "start",
        "--api-key-auth", "..."
      ]
    }
  }
}

Create a .cursor/mcp.json file in your project root with the following content:

{
  "mcpServers": {
    "Pay": {
      "command": "npx",
      "args": [
        "-y", "--package", "@nkwa-pay/sdk",
        "--",
        "mcp", "start",
        "--api-key-auth", "..."
      ]
    }
  }
}

You can also run MCP servers as a standalone binary with no additional dependencies. You must pull these binaries from available Github releases:

curl -L -o mcp-server \
    https://github.com/{org}/{repo}/releases/download/{tag}/mcp-server-bun-darwin-arm64 && \
chmod +x mcp-server

If the repo is a private repo you must add your Github PAT to download a release -H "Authorization: Bearer {GITHUB_PAT}".

{
  "mcpServers": {
    "Todos": {
      "command": "./DOWNLOAD/PATH/mcp-server",
      "args": [
        "start"
      ]
    }
  }
}

For a full list of server arguments, run:

npx -y --package @nkwa-pay/sdk -- mcp start --help

Requirements

For supported JavaScript runtimes, please consult RUNTIMES.md.

SDK Example Usage

Example

import { Pay } from "@nkwa-pay/sdk";

const pay = new Pay({
  apiKeyAuth: process.env["PAY_API_KEY_AUTH"] ?? "",
});

async function run() {
  const result = await pay.payments.get({
    id: "7112258c-4254-455f-a167-30549365ca9d",
  });

  console.log(result);
}

run();

Authentication

Per-Client Security Schemes

This SDK supports the following security scheme globally:

| Name | Type | Scheme | Environment Variable | | ------------ | ------ | ------- | -------------------- | | apiKeyAuth | apiKey | API key | PAY_API_KEY_AUTH |

To authenticate with the API the apiKeyAuth parameter must be set when initializing the SDK client instance. For example:

import { Pay } from "@nkwa-pay/sdk";

const pay = new Pay({
  apiKeyAuth: process.env["PAY_API_KEY_AUTH"] ?? "",
});

async function run() {
  const result = await pay.payments.get({
    id: "7112258c-4254-455f-a167-30549365ca9d",
  });

  console.log(result);
}

run();

Available Resources and Operations

availability

• check - Check which operators and operations are currently available.

payments

• get - Get the payment (collection or disbursement) with the specified ID.
• collect - Collect a payment from a phone number.
• disburse - Disburse a payment from your balance to a phone number.

Standalone functions

All the methods listed above are available as standalone functions. These functions are ideal for use in applications running in the browser, serverless runtimes or other environments where application bundle size is a primary concern. When using a bundler to build your application, all unused functionality will be either excluded from the final bundle or tree-shaken away.

To read more about standalone functions, check FUNCTIONS.md.

• availabilityCheck - Check which operators and operations are currently available.
• paymentsCollect - Collect a payment from a phone number.
• paymentsDisburse - Disburse a payment from your balance to a phone number.
• paymentsGet - Get the payment (collection or disbursement) with the specified ID.

Retries

Some of the endpoints in this SDK support retries. If you use the SDK without any configuration, it will fall back to the default retry strategy provided by the API. However, the default retry strategy can be overridden on a per-operation basis, or across the entire SDK.

To change the default retry strategy for a single API call, simply provide a retryConfig object to the call:

import { Pay } from "@nkwa-pay/sdk";

const pay = new Pay({
  apiKeyAuth: process.env["PAY_API_KEY_AUTH"] ?? "",
});

async function run() {
  const result = await pay.payments.get({
    id: "7112258c-4254-455f-a167-30549365ca9d",
  }, {
    retries: {
      strategy: "backoff",
      backoff: {
        initialInterval: 1,
        maxInterval: 50,
        exponent: 1.1,
        maxElapsedTime: 100,
      },
      retryConnectionErrors: false,
    },
  });

  console.log(result);
}

run();

If you'd like to override the default retry strategy for all operations that support retries, you can provide a retryConfig at SDK initialization:

import { Pay } from "@nkwa-pay/sdk";

const pay = new Pay({
  retryConfig: {
    strategy: "backoff",
    backoff: {
      initialInterval: 1,
      maxInterval: 50,
      exponent: 1.1,
      maxElapsedTime: 100,
    },
    retryConnectionErrors: false,
  },
  apiKeyAuth: process.env["PAY_API_KEY_AUTH"] ?? "",
});

async function run() {
  const result = await pay.payments.get({
    id: "7112258c-4254-455f-a167-30549365ca9d",
  });

  console.log(result);
}

run();

Error Handling

PayError is the base class for all HTTP error responses. It has the following properties:

| Property | Type | Description | | ------------------- | ---------- | --------------------------------------------------------------------------------------- | | error.message | string | Error message | | error.statusCode | number | HTTP response status code eg 404 | | error.headers | Headers | HTTP response headers | | error.body | string | HTTP body. Can be empty string if no body is returned. | | error.rawResponse | Response | Raw HTTP response | | error.data$ | | Optional. Some errors may contain structured data. See Error Classes. |

Example

import { Pay } from "@nkwa-pay/sdk";
import * as errors from "@nkwa-pay/sdk/models/errors";

const pay = new Pay({
  apiKeyAuth: process.env["PAY_API_KEY_AUTH"] ?? "",
});

async function run() {
  try {
    const result = await pay.payments.get({
      id: "7112258c-4254-455f-a167-30549365ca9d",
    });

    console.log(result);
  } catch (error) {
    // The base class for HTTP error responses
    if (error instanceof errors.PayError) {
      console.log(error.message);
      console.log(error.statusCode);
      console.log(error.body);
      console.log(error.headers);

      // Depending on the method different errors may be thrown
      if (error instanceof errors.HttpError) {
        console.log(error.data$.details); // any[]
        console.log(error.data$.message); // string
        console.log(error.data$.statusCode); // number
      }
    }
  }
}

run();

Error Classes

Primary errors:

• PayError: The base class for HTTP error responses.
  • HttpError: Generic error.

Network errors:

• ConnectionError: HTTP client was unable to make a request to a server.
• RequestTimeoutError: HTTP request timed out due to an AbortSignal signal.
• RequestAbortedError: HTTP request was aborted by the client.
• InvalidRequestError: Any input used to create a request is invalid.
• UnexpectedClientError: Unrecognised or unexpected error.

Inherit from PayError:

• ResponseValidationError: Type mismatch between the data returned from the server and the structure expected by the SDK. See error.rawValue for the raw value and error.pretty() for a nicely formatted multi-line string.

Server Selection

Override Server URL Per-Client

The default server can be overridden globally by passing a URL to the serverURL: string optional parameter when initializing the SDK client instance. For example:

import { Pay } from "@nkwa-pay/sdk";

const pay = new Pay({
  serverURL: "https://api.pay.staging.mynkwa.com",
  apiKeyAuth: process.env["PAY_API_KEY_AUTH"] ?? "",
});

async function run() {
  const result = await pay.payments.get({
    id: "7112258c-4254-455f-a167-30549365ca9d",
  });

  console.log(result);
}

run();

Custom HTTP Client

The TypeScript SDK makes API calls using an HTTPClient that wraps the native Fetch API. This client is a thin wrapper around fetch and provides the ability to attach hooks around the request lifecycle that can be used to modify the request or handle errors and response.

The HTTPClient constructor takes an optional fetcher argument that can be used to integrate a third-party HTTP client or when writing tests to mock out the HTTP client and feed in fixtures.

The following example shows how to use the "beforeRequest" hook to to add a custom header and a timeout to requests and how to use the "requestError" hook to log errors:

import { Pay } from "@nkwa-pay/sdk";
import { HTTPClient } from "@nkwa-pay/sdk/lib/http";

const httpClient = new HTTPClient({
  // fetcher takes a function that has the same signature as native `fetch`.
  fetcher: (request) => {
    return fetch(request);
  }
});

httpClient.addHook("beforeRequest", (request) => {
  const nextRequest = new Request(request, {
    signal: request.signal || AbortSignal.timeout(5000)
  });

  nextRequest.headers.set("x-custom-header", "custom value");

  return nextRequest;
});

httpClient.addHook("requestError", (error, request) => {
  console.group("Request Error");
  console.log("Reason:", `${error}`);
  console.log("Endpoint:", `${request.method} ${request.url}`);
  console.groupEnd();
});

const sdk = new Pay({ httpClient });

Debugging

You can setup your SDK to emit debug logs for SDK requests and responses.

You can pass a logger that matches console's interface as an SDK option.

[!WARNING] Beware that debug logging will reveal secrets, like API tokens in headers, in log messages printed to a console or files. It's recommended to use this feature only during local development and not in production.

import { Pay } from "@nkwa-pay/sdk";

const sdk = new Pay({ debugLogger: console });

You can also enable a default debug logger by setting an environment variable PAY_DEBUG to true.