What is the secret of Dropbox's success?

Why is Dropbox so much more successful than many other sites that offer/offered essentially the same service?

The first generation of "internet hard drive" companies (xdrive, idrive, etc) were based on the old LAN model of a file share that happens to live on the Internet. Accessing every file over the internet was slow, creating a ton of friction.

Dropbox provided true synchronization technology, so performance was fast and you could continue to work on files offline.

Furthermore:

1. the team had great Windows programmers. It is actually technically somewhat challenging to figure out which files have changed in an arbitrary Windows folder quickly and reliably. The APIs that are supposed to tell you this are somewhat mysterious and problematic, so making this part "just work" was actually technically more challenging than you would think
2. The team did a great job of supporting Linux and Mac early on, gaining a toehold among early adopters
3. The product made a simple promise and then delivered on that promise, while their competitors were making complicated promises and failing to deliver
4. They nailed the freemium model, providing enough free storage (2GB) that everyone could use Dropbox for free for most of their needs for years, until they became "true believers" and decided to start dumping EVERYTHING in their dropbox. Evernote got this right, too.

Opinions vary, but I think one of the key ingredients in their success was the "it just works" factor.

Dropbox took a seemingly simple issue that people had struggled with forever (easy sharing of files over a network) and made it a transparent process.

I think it also helped that the service didn't also co-market itself as a shady way to share copyright material (eg: the peer-to-peer networks of yore that claimed they were for easy sharing, but just happened to be filled with movies, porn, and mp3's).

Dropbox is an excellent example of finding a common pain point for consumers and solving that one specific problem in a highly efficient and effective manner.

Drew Houston actually has presentation on this called Startup Lessons Learned. It will run you through most of what you want to know.

• It's simple
• It's easy to install
• It works without interupting me
• It solves a real problem most people have
• It's free to try
• To upgrade, I have to tell people
• They had 20,000+ users before they even finished the product

When I got hooked on Dropbox there weren't really that many alternatives to it. There were a few that offered a backup + some sort of syncing interface on top of Amazon S3 and there was Microsoft's Live Mesh which was in beta and didn't look very appealing at the time.

Here is why I personally think DB was successful.

1. It's extremely simple to use and targeted to solve a common pain point of transparently syncing, backing up and sharing files for end users.
2. It's truly cross-platform from day one (Windows, OS X, Linux, and later the mobile platforms)
3. It's also viral, because when you share a folder you essentially send an invite out to the person to join dropbox in order to access the folder. This was later further fuelled by a referral scheme, where the inviter gets extra Dropbox space per referral.
4. Good media coverage, even when they were in the private invite stage.

Dropbox is a very simple tool and simplicity is very attractive when it comes to a complex problem like folder syncing. Dropbox is also totally painless. It works on Windows, Linux and Mac. Read about some more reasons here http://www.itworld.com/software/235425/more-reasons-why-dropbox-has-won-so-many-geeky-hearts