Accept Payments with Paystack in Flask

pip install flask requests python-dotenv

# app.py
import os
import uuid
import requests as http_requests
from flask import Flask, request, redirect, render_template, jsonify
from dotenv import load_dotenv

load_dotenv()

app = Flask(__name__)
PAYSTACK_SECRET = os.environ.get('PAYSTACK_SECRET_KEY')
BASE_URL = os.environ.get('BASE_URL', 'http://localhost:5000')

@app.route('/pay', methods=['POST'])
def initialize_payment():
    email = request.form.get('email')
    amount = float(request.form.get('amount', 5000))
    reference = 'order_' + uuid.uuid4().hex[:12]

    response = http_requests.post(
        'https://api.paystack.co/transaction/initialize',
        json={
            'email': email,
            'amount': int(amount * 100),
            'reference': reference,
            'callback_url': BASE_URL + '/payment/callback',
        },
        headers={
            'Authorization': 'Bearer ' + PAYSTACK_SECRET,
            'Content-Type': 'application/json',
        },
    )

    data = response.json()

    if data.get('status'):
        # TODO: Save order to database
        return redirect(data['data']['authorization_url'])

    return 'Initialization failed: ' + data.get('message', 'Unknown error'), 400

@app.route('/payment/callback')
def payment_callback():
    reference = request.args.get('reference') or request.args.get('trxref')

    if not reference:
        return 'Missing reference', 400

    response = http_requests.get(
        'https://api.paystack.co/transaction/verify/' + reference,
        headers={'Authorization': 'Bearer ' + PAYSTACK_SECRET},
    )

    data = response.json()

    if data.get('status') and data['data']['status'] == 'success':
        amount = data['data']['amount'] / 100
        currency = data['data']['currency']

        # TODO: Verify amount matches database, mark order as paid
        return 'Payment successful! ' + currency + ' ' + str(amount)

    return 'Payment not successful', 400

If your frontend is a separate SPA (React, Vue, etc.), return JSON instead of redirecting:

@app.route('/api/pay', methods=['POST'])
def api_initialize():
    data = request.get_json()
    email = data.get('email')
    amount = data.get('amount', 5000)
    reference = 'order_' + uuid.uuid4().hex[:12]

    response = http_requests.post(
        'https://api.paystack.co/transaction/initialize',
        json={
            'email': email,
            'amount': int(amount * 100),
            'reference': reference,
        },
        headers={
            'Authorization': 'Bearer ' + PAYSTACK_SECRET,
            'Content-Type': 'application/json',
        },
    )

    result = response.json()

    if result.get('status'):
        return jsonify({
            'authorization_url': result['data']['authorization_url'],
            'access_code': result['data']['access_code'],
            'reference': result['data']['reference'],
        })

    return jsonify({'error': result.get('message')}), 400

@app.route('/api/verify')
def api_verify():
    reference = request.args.get('reference')
    if not reference:
        return jsonify({'error': 'Missing reference'}), 400

    response = http_requests.get(
        'https://api.paystack.co/transaction/verify/' + reference,
        headers={'Authorization': 'Bearer ' + PAYSTACK_SECRET},
    )

    data = response.json()

    if data.get('status') and data['data']['status'] == 'success':
        return jsonify({
            'success': True,
            'amount': data['data']['amount'] / 100,
            'currency': data['data']['currency'],
        })

    return jsonify({'success': False}), 400

1. Use gunicorn. Do not run Flask's development server in production. Use gunicorn behind nginx.
2. HTTPS required. Paystack requires HTTPS for callback and webhook URLs.
3. CORS. Install flask-cors if your frontend is on a different domain.
4. Set up webhooks. See Handle Paystack Webhooks in Flask.
5. Validate amounts. Check amounts against your database, not client input.
6. Switch keys. Use sk_live_ in production.

This guide is part of the Paystack integration guides by language and framework series.

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