Atlanta has long held the reputation of "underrated startup hotbed." This year's Inc. 5000 ranking of fastest-growing companies in America confirms it: The city is home to 10 of the top 350 slots on the list. Only four other cities--Chicago, Los Angeles, New York City, and San Francisco--have higher concentrations of top-ranked ventures. From mobile health screenings to human hair extensions, here are those 10 thriving businesses:

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10. Ally Commerce

2018 Inc. 5000 rank No. 338 Three-year growth 1,468% 2017 revenue $3.9M

Running an e-commerce retailer requires handling a broad range of tasks, from sales and marketing to customer service and tax management. While plenty of apps exist to help make each function more efficient, Ally Commerce helps businesses by integrating all its apps into one platform.

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9. Birdsey Construction Management

2018 Inc. 5000 rank No. 326 Three-year growth 1,506% 2017 revenue $3.1M

Only five people work at this residential renovation contracting company, but it's not as small as it seems. That's because it's one of five affiliate businesses connected to the Birdsey Group, an Atlanta-based real estate consulting firm that itself made the Inc. 5000 in 2015.

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8. Peachcap

2018 Inc. 5000 rank No. 320 Three-year growth 1,537% 2017 revenue $8.3M

Billionaires often employ multiple types of advisers to handle their financial affairs. Peachcap aims to offer that style of financial management for non-billionaires by offering advice for individuals, as well as financial intelligence for wealth management companies.

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7. Springbot

2018 Inc. 5000 rank No. 301 Three-year growth 1,640% 2017 revenue $5.6M

The software company integrates different forms of marketing data--like email, social media, and Amazon marketplace selling--into one dashboard. Springbot grew out of Flashpoint, a Georgia Tech-affiliated startup accelerator, in 2012.

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6. Private Label Extensions

2018 Inc. 5000 rank No. 278 Three-year growth 1,776% 2017 revenue $4.2M

Hair extensions are a lucrative business, and this wholesaler wants to help companies take advantage. Private Label Extensions offers services from website-building to the actual purchasing of human hair extensions, weaves, and mink eyelashes.

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5. IT Works Recruitment

2018 Inc. 5000 rank No. 250 Three-year growth 1,951% 2017 revenue $10.5M

IT Works Recruitment, a 14-year-old British firm, opened its first American office in 2013. That Atlanta-based office has grown into a 36-employee shop that matches IT professionals with jobs in health care, business systems, and Salesforce positions.

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4. QASymphony

2018 Inc. 5000 rank No. 230 Three-year growth 2,053% 2017 revenue $10.7M

If you're creating software, you need a platform on which to test it. Four-year-old QASymphony makes one such testing ground that's already attracted more than 15,000 users and 600 customers--including Zappos, Barclays, and Office Depot.

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3. Recleim

2018 Inc. 5000 rank No. 101 Three-year growth 3,621% 2017 revenue $36.1M

This recycling startup's goal is to filter out the harmful chemicals in large appliances, while recovering the reusable metals, plastics, and glass.  Recleim's biggest claim to fame to date: saving a dying South Carolina town.

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2. Thought Logic Consulting

2018 Inc. 5000 rank No. 93 Three-year growth 3,752% 2017 revenue $11.2M

The company offers consulting for the finance, IT, sales, and logistics industries. More than half of Thought Logic Consulting's 53 employees have worked with or for the Big Four accounting firms: Ernst & Young, Deloitte, KPMG, and PwC. This is its second consecutive appearance near the top of the Inc. 5000.

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1. Healpros

2018 Inc. 5000 rank No. 90 Three-year growth 3,824% 2017 revenue $8.8M

Many patients can't make regular visits to a doctor's office for health screenings.  Healpros offers mobile versions of common tests that can be administered in your home, including screenings for diabetes, kidney disease, colon cancer, and osteoporosis.