There are several popular one-click checkout solutions that are used by ecommerce businesses. Here are some of the most commonly used ones:

Careem Pay One-Click Checkout: Careem Pay offers One-Click Checkout that enables more than 50m+ Careem users to shop on Careem Pay enabled merchants without adding their personal, shipping, and even payment details. Shoppers can seamlessly  checkout your  store if it has Careem Pay One-Click Checkout enabled, thereby increasing your store ecommerce conversions 

Amazon Pay: Amazon Pay is a one-click checkout solution that allows customers to use their Amazon account information to quickly and easily complete their purchases on other websites.

PayPal One Touch: PayPal One Touch is a one-click checkout solution that allows customers to use their PayPal account information to complete their purchases with just one click.

Apple Pay: Apple Pay is a one-click checkout solution that allows customers to use their Apple account information to quickly and easily complete their purchases on other websites and in physical stores.

Google Pay: Google Pay is a one-click checkout solution that allows customers to use their Google account information to complete their purchases with just one click.

Shopify Pay: Shopify Pay is a one-click checkout solution that is available to businesses using the Shopify ecommerce platform. It allows customers to save their Conversion optimization tools shipping and billing information for fast and easy checkout on future purchases.

These one-click checkout solutions can help ecommerce businesses improve their conversion rates and increase customer satisfaction by providing a fast and convenient checkout process. Overall, one-click checkout has become not just popular but very successful amongst merchants  because it offers a fast, convenient, and secure checkout process that can reduce friction and increase customer satisfaction. However, it is important to carefully evaluate the features and benefits of each solution to determine which one is the best fit for your business and your customers.