These four big start-ups could be toast after Apple's news

Apple took the wraps off an array of new products during the keynote that kicked off its annual developers conference in San Francisco on Monday. The company refreshed its mobile iOS operating system and its Mac software and introduced new services and tools, covering everything from music to payments to maps.

For the Apple faithful, it was another banner day full of happy news. But some tech companies watching have reason to be worried:

Evernote

Apple beefed up the built-in note taking app that comes on iPhones and iPads. The new version of Notes lets you add hand-drawn doodles or sketches to your notes, create checklists and directly access the device's camera to include photos. The new features are sure to raise the competition with Evernote, the eightyear-old startup that has won a loyal following (and a $1 billion valuation) for its online note-taking app, as well as Microsoft's OneNote product.

Flipboard

Say goodbye to Newsstand and say hello to News. Apple scrapped the previous version of its app for news publishers, which basically served as a hub to launch other news apps such as the New York Times. In its place it introduced News, which presents stories from your favourite publishers in a graphics-rich stream. It looks a lot like what users of Flipboard, a popular newsreading app, are accustomed to.

Spotify, Rdio, SoundCloud

Spotify has been the top dog in the streaming music business for several years now, with 15 million paying subscribers at last count.

But the competitive landscape is about to undergo a massive change, now that Apple has announced plans to launch a music streaming service.

Apple's once dominant digital music download business may be declining, but the company still has huge influence in the music biz. Its entry into the market was no surprise to competitors. Rdio was ready for the announcement with a clever letter "welcoming" Apple to the party.

Spotify CEO Daniel Ek tweeted a comment during Apple's announcement that some interpreted as a reaction to the on-stage events, but later deleted the tweet.

The "Apple Music Connect" feature hedges in on SoundCloud's social music discovery territory, and it was unveiled by rapper Drake, an avid SoundCloud user, during their keynote address.