The mobile payment market is one of the most innovative sectors in retail and last week it emerged Amazon is considering trying its hand, by turning the Kindle into a till.

It is considering adapting its Kindle e-reader to allow bricks-and-mortar retailers to use them as checkouts, with credit card readers, web development and data analysis all potentially in the offing.

But while Amazon is the first retailer to try this, it’s certainly not the first firm to eye up the soon to be hugely lucrative mobile payment market.

The range of hardware and software on offer to retailers interested in mobile point of sale is varied, and is getting bigger all the time. It’s a fragmented market and it is unclear as yet which – if any – business will emerge as a clear leader. Not even Amazon will find this an easy market to crack. Retail Week takes a look at its potential competition.

1) Square

Square is the brainchild of Twitter founder Jack Dorsey. It involves attaching a small, white, square card reader to an iPad and is popular with smaller businesses. It is not yet available in the UK.

2) Visa

Visa has ploughed its efforts into contactless payment using Near Field Communication (NFC) technology. Last year there were around 51 million contactless Visa cards in use in Europe, and Visa expects this to grow. It says that, by 2020, 50% of its transactions will be mobile. It has embarked on partnerships with mobile operators and banks in some countries which enable shoppers to pay using mobile phones. However, despite retailers such as Dixons signing up to its V.me digital wallet, the only UK bank to have signed up so far is Nationwide.

3) Apple

Apple hasn’t properly entered the mobile payment race yet – it seems to be as reluctant as most retailers to pin its colours to a mast. But there are some indications of the direction it will go in. It continues to snub NFC, and instead appears to be looking at using fingerprints and Bluetooth low energy beacons. Capacity for both was built into the iPhone 5, with beacons working in a similar way to wi-fi but communicating more seamlessly with mobile phones.

4) PayPal

PayPal has been the one of most experimental of the big names in payment. Its app, which can be used to pay in-store, has been rolled out by retailers including the JD Sport Group, Oasis and Karen Millen, and PayPal has not been short of innovative ideas. Its PayPal Here service is a card reader and app designed for merchants to take payment using tablets, and it is working with a variety of partners on integrating PayPal services into the point of sale systems of large brands. In addition, it is working on PayPal Beacon, a service that will use Bluetooth beacons.

5) Worldpay

Worldpay is a global payments processor working with a range of partners – it is, for instance, working with Visa to provide its V.me digital wallet service.

6) Monitise

Monitise is another payments processor working with the likes of HSBC and Natwest to provide mobile banking services.

7) Podifi

Podifi is one of a few loyalty apps available on the market, working in a similar way to Apple’s Passbook – retailers who sign up can enable their shoppers to redeem coupon and loyalty offers via their smartphone. It uses a small pod which connects to retail tills and communicates with phones via wi-fi.

8) Proxama

Proxama provides NFC technology and is working with Argos. The Argos project currently allows shoppers to download the retailer’s app by swiping download cards in store, but it has the potential to be converted into a payment technology. Argos has no plans to do so, but contactless terminals are able to communicate with NFC-enabled phones and cards. If banks and phone networks manage to partner up, NFC may yet take off in payment – and this project suggests there are other potential uses for it even if it doesn’t.

9) Software suppliers

Software-based services are offered by a number of vendors, including PCMS, which is working with John Lewis and Omnico, which is working with Paperchase. This point-of-sale software can be used on Apple, Android or Windows and integrated with existing point-of-sale systems.

10) Hardware suppliers

Omnico also has a device called the Digipos Freedom Tablet, which is a dedicated tablet point-of-sale device. The tablet has been designed for the in-store experience, while joining up stores, ecommerce and mobile infrastructure. Tablets are popular with some retailers because they allow sales assistants to move in front of the till to serve the customer more personally, with access to real-time information on products, offers and stock. Suppliers including Wincor Nixdorf also make point-of-sale tablets.

11) Zapp

Retailers, in many cases, are happier to try out less expensive payment apps than mobile payment services that require large scale infrastructure investment. One example is Zapp. It is working with Worldpay to provide an app that uses codes sent to the mobile to verify a transaction, making infrastructure changes unnecessary. WHSmith and Superdrug have signed up – the service is set to be rolled out this year. Five banks, including HSBC, First Direct, Nationwide, Santander and Metro Bank, have signed up as well.

12) Znap

Znap is another app-based service, owned by MPayMe, which uses QR codes. Shoppers scan can QR code to check into a location. They can then order and pay over their mobile, and pick up their goods from the store.

13) Paddle

Paddle is an online payment service that can be installed on a website in the same way as PayPal. There is also a mobile app – M&S trialled the Paddle service in 2013.

14) MoPowered

Firms such as MoPowered work with retailers who want to build their own mobile payment services. In this case, it is working with retailers including Next and Supergroup.