Methodology: How this list is ranked

We looked at the following factors when we adjust our rankings and publish a new version of the list:

Revenue: This is one of the most important factors in our ranking. Companies with robust businesses have revenues they can talk about in dollars (not blind percentage "growth" claims). Companies that are modest about their revenues are usually modest for good reason.

We tried as hard as possible to obtain net revenue estimates. We are not auditors and we don't have access to the companies' accounts, so we have had to rely on our own reporting, that of other publications, estimates from industry experts, and figures given by the companies themselves. This ranking shouldn't be looked at as an exact science, but more a temperature check of how companies are performing.

Total employees: Companies tend to hire more people because they're handling more business. Headcount is a good proxy for growth — although having too many employees can drive down margins and veer companies away from their core focus.

Funding: Investors tend to want their money back. So companies that have taken a lot of investment funding are under greater pressure to IPO/exit than those that have not. VC investment is also an indicator (although not the indicator) of confidence in a company.

Reputation: It's great that some companies like to grow quietly without the distraction of the media spotlight (some even requested we didn't put them in the list) — unfortunately that means we're less likely to know about them.

But, as previously mentioned, we also asked industry experts for their suggestions on which companies should feature, so we could get a good mixture of those companies with a good PR machine and those that are a little more off-the-radar.

Inevitably, we will miss a few companies that should have been on the list — but we hope this is a good reflection of some of the most exciting startups in this space.