General information:
Checkout, a process of paying for online purchases, may get rather complicated and irritating for customers when they have to fill in and confirm lots of order forms – such as product, contact, payment, shipping and other required information. The experience of many online shops shows that complicated checkout processes with numerous steps to take disappoint customers. They do not want to waste their time on these complicated order forms and they leave such online shops without making any purchases.
Default Magento checkout is a five-step process, which may be quite time consuming for your customers. As a result, you may lose some of your customers - your cart abandonment rates will increase. Magento One Step Checkout solves this problem for you by combining all these steps into a simple and user-friendly all-in-one form.
Magento One Step Checkout module makes checkout process really simple by cutting down the number of pages to fill in to a single one. Logged in customers who have already entered their information will just need a few clicks to make and confirm their orders. With our One Step Checkout you will simplify checkout process for your customers and provide them with positive shopping experience. Magento One Step Checkout extension supports latest versions of Firefox, Opera, Chrome, Safari, and Internet Explorer.
Simplify your checkout process and you will increase your online sales! Magento One Step Checkout will allow your customers to enjoy fast and easy purchases.

Version 2.00 Updates:
- Improved code (php,phtml,js). All js moved from jQuery to native magento's prototype
- Delivery Date calendar
- Order comments
- Gift Message
- Ability to hide registration filelds (Telephone, Country, City, Region, Zip, Fax, Company)

Key features:
- One-page Checkout
- Checkout process is very simple – only one step to place an order!
- No page reload
- Customer account may be created while placing an order
- Possibility to checkout as a guest
- Reduced Shopping Cart Abandonment rates
- Easy installation – all you have to do is upload your files
- Easy modification of CSS / layout with regular Magento templates and style sheets
- Auto-update of prices and totals when shipping/payment method is selected
- Auto-update of available shipping methods when a certain country, zip code or region is selected
- Auto-update of available payment methods when a certain country, zip code or region is selected
- Possibility to add a gift message when placing an order
- Possibility to enter a coupon code directly on the checkout page
- Possibility to enable/disable "Subscribe to Newsletter" checkbox on a checkout page
- Possibility to enable/disable "Same as Billing" shipping address
- No Magento core files modification
- Email support for our clients

How it looks:

Among all the pages of an online shop, the checkout is indeed the most important. This is why it is crucial to create this page strategically, and to optimise it constantly, to make sure that the checkout process is as smooth as possible. Remember that the aim of every online shop is to sell: the more you provide a high quality customer experience and the more your shop will perform. 

In other words, these are the main characteristics that every good checkout process should have:
1) Great usability: clear layout, breadcrumb on the top of the page indicating all the steps of the checkout, so that the customer can have a perception of how long is going to take.
2) No distractions. Postpone any possible marketing call to action in the thank you page or before the checkout. 
3) Address form and Payment Methods. Make sure that you have as many payment methods as possible and that all the official logos are well displayed so that the customer can trust the online shop. Also, make sure that your forms are working perfectly (check that the data validation is enabled on every single field of the form, and a clear error message is displayed). 

Magento One Page Checkout basically will include all these features and even more in a pre-engineered template that you will just need to integrate in your online shop. The page includes the login section (with the possibility to have the guest login), billing and shipping address fields, payment information and checkout, all in one page. 

The Magento One Page Checkout has been strategically created to help everyone who is approaching to the world of eCommerce to have a ready made optimised and performing checkout process.