I primarily use online carts for taking payments from clients of mine with a "Pay what you want" price option. This allows my clients to "top up" their accounts with more funds, or pay an invoice I sent them - all from the same checkout page.

The Upsell Plugin for WordPress was very easy to install, and I was able to get a checkout page up and running very quickly with the page builder of my choice, using Stripe - all without any headaches or issues.

This is a lightweight plugin that is not going to slow down your WordPress site. The checkout forms load quickly, look good, and offer a level of customization that you don't find in a lot of other plugins.

There have been other plugins on Appsumo that promised a quick and easy setup, but this one truly does.

I use a wide variety of plugins for myself and clients, and the one thing that people are always looking for is a nice cart plugin, especially for digital products.

I'm only a few days into using this plugin, but have already enjoyed using it. Support is quick to respond and very helpful as well.

Here is what I like about the plugin so far:
- Quick and easy setup
- NO WOOCOMMERCE!!!!!!!
- "Pay what you want" price
- Ability to have bump offers (and it looks like I can add multiple bump offers).
- Ability to have one click upsell and downsell features (hence the name "Upsell" plugin).
- You can use this with ANY WordPress page builder
- The form is good, and works great.

Things that need improving in the plugin
- This uses the Stripe API keys, which means only cards work. I would love to see an integration with the Stripe oAuth connection where other payment methods like Google Pay, Apple Pay, Cash App, and many others can be used.
- I would like to see this plugin use the WordPress Customizer or Blocks to build and add my own styles to the checkout form (easier than using custom CSS).
- A better UI. Although it's good, and lightweight plugin, I feel the Admin menus could offer a little more styling.
- Don't rely on Advanced Custom Fields Pro for fields in the plugin. So my suggestion here is to build your own fields in WordPress without relying on a 3rd party solution such as ACF. I do appreciate this is built in so I don't have to install or buy a license for ACF Pro

I want to point out that these "things that need improved" are honestly very small trivial things that are more of a "would like to have" than anything that should be considered a red flag. This comes with my 20 years of WordPress experience and experience with carts and cart plugins.

If you are looking for a simple, easy to use cart plugin for your digital products, services, and other kinds of products, I would suggest to give Upsell Plugin a try.