Which apps will become WhatsApps? After the billion-dollar purchase of the messaging service, a guide to the best UK tech firms

Facebook's $19bn (£11.4bn) takeover of mobile messaging app WhatsApp on Thursday was just the latest, and most expensive, deal in a mergers and acquisitions splurge that has seen companies from Palo Alto to Tel Aviv swallowed up. The UK has had its fair share of the action, as British start-ups have begun to attract the attention of Silicon Valley's biggest players.

Last month, a secretive London artificial intelligence start-up, DeepMind, was acquired for £400m by Google – just days before the struggling US gaming firm Zynga shelled out £320m for the Oxford-based games studio NaturalMotion.

Most people outside the tech world had never heard of these firms – and there are plenty more UK tech firms flying below the radar which could soon be eyeing a million-dollar exit.

Here's a guide to the hottest tech start-ups of which you may never have heard.

DataSift

Founded by the inventor of Twitter's retweet button, Nick Halstead, the Reading-based firm is one of only two companies across the globe with access to Twitter's so-called "firehose" data stream.

The company gets all the raw data from the platform, converting it into something understandable and manageable – who is saying what and where.

As well as Twitter, the four-year-old company has data deals with other major social networks and intends to move into analysing internal business data.

Who might be interested? The most likely candidate would be Twitter. The social network has been ramping up its offerings to businesses since its float, and roughly 15 per cent of its revenue currently comes from selling data and user information.

However, DataSift founder Halstead says he's committed to a stock market float of the firm within three to four years.

TransferWise

A peer-to-peer international money transfer business, co-founded by Skype's first employee, Taavet Hinrikus. The service cuts out the costly transfer fees typically charged by existing companies such as Western Union. It has transferred more than £250m since launching in 2011, and last year PayPal co-founder Peter Thiel invested $6m in the London-based business.

Who might be interested? The banks. The financial sector is quickly waking up to the fact that if it is not careful, new financial technology (or FinTech) firms could eat their lunch. Alternatively, TransferWise could be a target for a bigger tech firm in the area, such as mobile payment firm Square, run by Twitter co-founder Jack Dorsey.

Grabyo

The London-based company lets broadcasters edit and share TV clips on social media in real time. It launched the service on Twitter last year in time for Premier League transfer deadline day.

Who might be interested? Grabyo is another company that could help Twitter beef up its business offering, and the microblogging site already works with Grabyo on its "Amplify" package in the UK. Alternatively, an advertising giant such as WPP could poach the firm.

SpaceApe

A hotly tipped games studio, founded by former employees of gaming studios Playfish, Electronic Arts and Mind Candy. While it only set up shop in 2012, SpaceApe is already attracting attention for the success of its mobile and Facebook game Samurai Siege. Chief executive John Earner knows a thing or two about adventure – before turning to gaming, he served in the US Navy, hunting smugglers.

Who might be interested? Zynga may be interested in SpaceApe, which, along with NaturalMotion, could help it crack mobile. Google could also be tempted by the firm's work on artificial intelligence.

SwiftKey

It may not sound like much, but this predictive keyboard app is seen as one of the hottest start-ups on the UK technology scene. The firm was co-founded by Ben Medlock, who has a PhD from Cambridge in language-based artificial intelligence; the app learns how you speak, suggesting phrases and even whole sentences as you type.

Who might be interested? Apple and Google. SwiftKey's trailblazing technology would be valuable to both firms as a way to improve their smartphones' software.

YPlan

Set up by two Lithuanians in London, YPlan is a "spontaneous booking" app that lets people buy last-minute tickets to a curated selection of events in town that night. The start-up works with more than 550 event partners in London, including the Barbican, South Bank Centre and the Comedy Store. The app has been downloaded more than 500,000 times since launching in London in late 2012, and has since launched in New York, with San Francisco to follow soon.

Who might be interested? Social network Foursquare could use the app to reinvigorate its service. Facebook may also throw its hat in the ring, with its European partnership head, Julien Codorniou, recently calling YPlan "a very important partner". Alternatively dotcom-boom survivor Lastminute.com could use YPlan as a way to break into mobile.

Digital Shadows

The London-based cyber-security firm helps businesses and individuals keep track of the crumb trails they leave online, allowing them to spot vulnerabilities. Founded less than three years ago by a veteran of BAE's cyber-security business Detica, the company already counts some of the world's leading banks as paying clients.

Who might be interested? Industry watchers are predicting a cyber-security "gold rush" this year as big players such as McAfee and Symantec search out new ways to tackle digital threats. At the start of the year, US giant FireEye paid $1bn for Mandiant, the firm that analysed Chinese attacks on The New York Times last year.

Skyscanner

Edinburgh-based Skyscanner helps people find cheap flights, comparing routes, airlines and timings to find the best deals. Last year, Sequoia Capital, a Silicon Valley venture capital firm that first backed Apple, invested in it, valuing it at $800m. The business is now aiming to crack the US and Latin America.

Who might be interested? In 2008, Microsoft paid a reported $115m for Farecast, a company offering a similar service, building it into its Bing search engine. Google or Yahoo! may be interested in Skyscanner for similar reasons.