rexedge/paystack-setup

Paystack Setup

Set up the foundational Paystack API client and environment configuration for TypeScript/JavaScript server-side applications.

API Fundamentals

| Property | Value | | --- | --- | | Base URL | https://api.paystack.co | | Auth Header | Authorization: Bearer SECRET_KEY | | Content Type | application/json | | Response Format | { status: boolean, message: string, data: object } | | Amount Unit | Subunit of currency (multiply display amount × 100) | | Transaction ID | Unsigned 64-bit integer — use string in TypeScript |

Supported Currencies & Subunits

| Currency | Code | Subunit | Multiplier | | --- | --- | --- | --- | | Nigerian Naira | NGN | kobo | ×100 | | US Dollar | USD | cent | ×100 | | Ghanaian Cedi | GHS | pesewa | ×100 | | South African Rand | ZAR | cent | ×100 | | Kenyan Shilling | KES | cent | ×100 | | West African CFA | XOF | — | ×100 | | Egyptian Pound | EGP | piaster | ×100 | | Rwandan Franc | RWF | — | ×100 |

Environment Variables

Create a .env file (or .env.local for Next.js):

PAYSTACK_SECRET_KEY=sk_test_xxxxx        # Server-side only, NEVER expose to client
NEXT_PUBLIC_PAYSTACK_PUBLIC_KEY=pk_test_xxxxx  # Safe for client-side (Popup/InlineJS)

The secret key (sk_*) must NEVER appear in client-side code, browser bundles, or public repositories. The public key (pk_*) is safe for front-end use with Paystack Popup/InlineJS only.

Test keys start with sk_test_ / pk_test_. Live keys start with sk_live_ / pk_live_. Get them from the Paystack Dashboard under Settings → API Keys & Webhooks.

Install Dependencies

# For client-side Popup/InlineJS checkout
npm install @paystack/inline-js

# Or with pnpm / yarn
pnpm add @paystack/inline-js
yarn add @paystack/inline-js

No server-side SDK is needed — use the built-in fetch API with the helper below.

TypeScript API Client Helper

Create a reusable, type-safe Paystack client. Every other Paystack skill depends on this pattern:

// lib/paystack.ts
const PAYSTACK_SECRET_KEY = process.env.PAYSTACK_SECRET_KEY;

if (!PAYSTACK_SECRET_KEY) {
  throw new Error("PAYSTACK_SECRET_KEY is not set in environment variables");
}

export interface PaystackResponse<T = unknown> {
  status: boolean;
  message: string;
  data: T;
}

export interface PaystackListResponse<T = unknown> {
  status: boolean;
  message: string;
  data: T[];
  meta: {
    total: number;
    skipped: number;
    perPage: number;
    page: number;
    pageCount: number;
  };
}

export class PaystackError extends Error {
  constructor(
    message: string,
    public statusCode: number,
    public response?: unknown
  ) {
    super(message);
    this.name = "PaystackError";
  }
}

export async function paystackRequest<T>(
  endpoint: string,
  options: RequestInit = {}
): Promise<PaystackResponse<T>> {
  const url = `https://api.paystack.co${endpoint}`;

  const response = await fetch(url, {
    ...options,
    headers: {
      Authorization: `Bearer ${PAYSTACK_SECRET_KEY}`,
      "Content-Type": "application/json",
      ...options.headers,
    },
  });

  const data = await response.json();

  if (!response.ok) {
    throw new PaystackError(
      data.message || `Paystack API error: ${response.status}`,
      response.status,
      data
    );
  }

  return data as PaystackResponse<T>;
}

Pagination

All list endpoints accept perPage (default: 50, max: 100) and page (default: 1) as query parameters. The response includes a meta object:

{
  "meta": {
    "total": 243,
    "skipped": 0,
    "perPage": 50,
    "page": 1,
    "pageCount": 5
  }
}

Build paginated queries like so:

const params = new URLSearchParams({
  perPage: "20",
  page: "2",
  from: "2024-01-01T00:00:00.000Z",
  to: "2024-12-31T23:59:59.000Z",
});
const result = await paystackRequest<Transaction[]>(`/transaction?${params}`);

Amount Conversion

Always convert display amounts to subunits before sending to Paystack, and convert back when displaying:

// Display → Paystack (multiply by 100)
const amountInKobo = Math.round(amountInNaira * 100);

// Paystack → Display (divide by 100)
const amountInNaira = amountInKobo / 100;

Use Math.round() to avoid floating-point issues like 19.99 * 100 = 1998.9999999999998.

HTTP Methods

| Method | Usage | | --- | --- | | POST | Create resources, initiate actions | | GET | Fetch, list, verify resources | | PUT | Update resources | | DELETE | Deactivate or remove resources |

Error Handling

Wrap Paystack calls in try/catch and handle the PaystackError class:

import { paystackRequest, PaystackError } from "@/lib/paystack";

try {
  const result = await paystackRequest<Transaction>("/transaction/verify/ref_123");
} catch (error) {
  if (error instanceof PaystackError) {
    console.error(`Paystack error ${error.statusCode}: ${error.message}`);
    // Handle specific status codes
    if (error.statusCode === 400) { /* bad request / validation error */ }
    if (error.statusCode === 401) { /* invalid secret key */ }
    if (error.statusCode === 404) { /* resource not found */ }
  }
  throw error;
}

Security Checklist

• Store PAYSTACK_SECRET_KEY in environment variables only, never in code
• Add .env and .env.local to .gitignore
• All Paystack API calls must run server-side (API routes, server actions, backend)
• Use HTTPS for all callback and webhook URLs
• Validate amounts server-side before initializing transactions
• Always verify transaction status server-side after payment, never trust client-side callbacks alone