Knit Pay is described as 'One plugin to integrate various Payment Gateways like Instamojo, Razorpay, Cashfree, Easebuzz, etc with WordPress plugins like WooCommerce, Easy Digital Downloads, Paid Memberships Pro, Learn Press, Give, Ninja Forms, Tourmaster, Memberpress, etc' and is an app in the Business & Commerce category. There are more than 50 alternatives to Knit Pay for a variety of platforms, including Online / Web-based, iPhone, Android, Mac and Windows. The best alternative is PayPal. It's not free, so if you're looking for a free alternative, you could try Litecoin or Apple Wallet. Other great apps like Knit Pay are Flattr (Paid), Stripe (Paid), Payoneer (Paid) and Amazon Pay (Freemium).
Flattr is a social micropayment service, that makes it easy for you to "flatter" things on the internet that you like. When you're registered to Flattr, you pay a small monthly fee of your own choosing.
Stripe helps you create any type of payments flow—from e-commerce to recurring billing and everything in between. Stripe enables you to accept payments in minutes. Stripe makes recurring and subscription-based billing easy.
Wallet keeps things like airline boarding passes, movie tickets, and gift cards all in one place, letting you scan your iPhone or iPod touch to check in for a flight, get into a movie, redeem a coupon, and more. Wallet is what you would use to set up Apple Pay.
DASH is an open source peer-to-peer cryptocurrency that uses a system called Darksend to add privacy to transactions. It allows you keep your finances private as you make transactions, similar to cash.
GNU Taler is a privacy-preserving payment system. Customers can stay anonymous, but merchants can not hide their income through payments with GNU Taler. This helps to avoid tax evasion and money laundering.