In Phoenix, a business that sells gas-fireplace logs for Arizona's chilly nights cohabitates with one that installs swimming pools for the sweltering summers. It's a contrast that highlights the diversity of the city's startup ecosystem, which can't be defined by just one or two industries. 

One element those businesses have in common, though, is how quickly they've increased revenue. The two--Grand Canyon Gas Logs and Emerald Pools and Spas--both appear on this year's Inc. 5000, a list of the fastest-growing private companies in America

This year, they'll be celebrated in their hometown at the Inc. 5000 conference and gala, October 10-12. Entrepreneurs representing many of the other companies that made the list will also be at the event, which features such speakers as Calm co-founder Michael Acton Smith, LearnVest founder Alexa von Tobel, and Away co-founder Jen Rubio. 

Ahead of the conference, here are the top 10 fastest-growing private companies in Phoenix, ranked by their three-year revenue growth rate. 

10. RevolutionParts

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2019 Inc. 5000 rank No. 1,043 | Three-year growth 401% | 2018 revenue $8.1M

The three-time Inc. 5000 list honoree helps automotive dealers streamline the process of selling car parts. Launched in 2013, the startup also helps dealers handle back-office work and data entry. 

9. Grand Canyon Gas Logs 

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2019 Inc. 5000 rank No. 938 | Three-year growth 453% | 2018 revenue $2.7M

Launched in 2014, this startup makes and sells lifelike fake logs for residential and commercial gas fireplaces. The company, which had 10 employees at the end of 2018, is making its Inc. 5000 debut this year. 

8. OH Partners 

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2019 Inc. 5000 rank No. 881 | Three-year growth 484% | 2018 revenue $46.3M

Making its seventh appearance on the Inc. 5000 list is marketing startup OH Partners. Launched in 2008, the company offers in-house consumer research, polling, and focus groups, along with strategic consulting, public affairs services, and campaign management for businesses and political candidates. 

7. Mi-One Brands 

2019 Inc. 5000 rank No. 721 | Three-year growth 607% | 2018 revenue $18.3M

Launched in 2009, this four-time Inc. 5000 honoree designs, engineers, and sells high-end vaporizer tools for tobacco and cannabis. In addition to vapes, the company makes cartridges, salts, and liquids. 

6. Emerald Pools and Spas

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2019 Inc. 5000 rank No. 684 | Three-year growth 640% | 2018 revenue $5.6M

With Phoenix's scorching heat, it's no surprise that a swimming pool company ranks high on the city's list of fast-growing businesses. What started as a family-run pool construction business in 2000 has expanded to include services including pool repair, remodeling, and cleaning. 

5. cloudIT 

2019 Inc. 5000 rank No. 595 | Three-year growth 747% | 2018 revenue $5.3M

Launched in 2015, cloudIT offers customers technology services like outsourced IT, custom-built cloud solutions, and hardware integration. Founder Vince Kent started the company, which makes its Inc. 5000 debut this year, after years working in the telecom industry.

4. Girikon

2019 Inc. 5000 rank No. 335 | Three-year growth 1,398% | 2018 revenue $2.8M

Girikon offers IT consultation and development services, including end-to-end Salesforce solutions and mobile app development. The company, which had 140 employees at the end of 2018, is making its Inc. 5000 debut this year. 

3. Transcend Security Solutions

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2019 Inc. 5000 rank No. 248 | Three-year growth 1,713% | 2018 revenue $8.3M

The security company, started by Chris Vetter and Shawn Crane in 2014, provides customers both virtual and physical protection: Transcend's services include uniformed guards, parking enforcement, security technologies, and alarm responses. 

2. Loanatik 

2019 Inc. 5000 rank No. 85 | Three-year growth 3,692% | 2018 revenue $9M

Founder Corey Schwartz launched Loanatik in 2004 with the goal of making the mortgage process easier for home buyers and the professionals aiding them. The company works with borrowers on residential mortgages and touts a simplified application process. 

1. Freestar 

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2019 Inc. 5000 rank No. 1 | Three-year growth 36,680% | 2018 revenue $36.9M

Co-founders David Freedman and Chris Stark got the idea for Freestar after Freedman started selling advertisements in a swimsuit calendar he created while in college. Now the startup, which has developed technology that helps publishers increase their online ad revenue, works with more than 300 clients and has offices in New York and Los Angeles.

Correction: An earlier version of this article mischaracterized the nature of Freestar's business. The company works in technology helping publishers increase their online advertising revenue.