It might seem difficult to get started in the stock market with just $3,000. But given enough time, even a modest $3,000 investment in the right growth stock can blossom into enough cash to buy a car, or even a house.

For example, a $3,000 investment in Amazon 10 years ago would now be worth more than $27,000. That same $3,000 investment in Tesla would be worth over $370,000 today.

A person is showered with cash.

Image source: Getty Images.

Not every growth stock will become the next Amazon or Tesla. But here are three promising growth stocks that could at least double a $3,000 investment: Fortinet (FTNT 1.92%), Impinj (PI 3.14%), and Monday.com (MNDY 2.65%).

1. Fortinet

Fortinet is a cybersecurity company that launched its first next-gen firewall, FortiGate, two decades ago. That firewall is now the heart of its "Security Fabric," which provides end-to-end protection services for on-premise, cloud-based, and Internet of Things (IoT) devices.

Fortinet has grown like a weed since its public debut in late 2009. Between 2009 and 2021, its annual revenue rose from $252 million to $3.34 billion, representing a compound annual growth rate (CAGR) of 24%. It's been profitable on a GAAP (generally accepted accounting principles) basis ever since its public debut, while its non-GAAP net income increased at a CAGR of 29% from $30 million in 2009 to $666 million in 2021.

It might seem tough for a company to maintain those growth rates for more than a decade, especially since Fortinet already serves over half a million customers worldwide, including most of the Fortune 500 -- yet it still expects its revenue to grow another 30%-32% this year as its non-GAAP earnings per share (EPS) increases 27%-33%. Those are impressive growth rates for a stock that trades at a reasonable 38 times forward earnings.

Fortinet will likely continue to grow for decades to come as the cybersecurity market, which is traditionally resistant to inflation and other macro headwinds, continues to expand. Therefore, this stock could certainly double your money -- or generate even bigger gains -- over the long term.

2. Impinj

Impinj is one of the top producers of RFID (radio frequency identification) tags, readers, and software in the world. RFID tags are widely used to track product inventories as they pass through the supply chain and retail stores.

Several secular tailwinds have been driving RFID sales higher in recent years. Brick-and-mortar retailers are increasingly using RFID tags to track their merchandise sales to analyze their sales trends, while logistics companies are relying on RFID tags to streamline their deliveries. The ongoing supply chain disruptions also highlight the importance of RFID tags.

Impinj went public in 2016, and its annual revenue increased at a CAGR of 11% from $112 million to $190 million between 2016 and 2021, even as the pandemic temporarily stunted its growth by shutting down retailers throughout 2020. But looking ahead, analysts expect Impinj's revenue to rise 29% this year and grow another 22% in 2023 as those headwinds dissipate and the secular tailwinds pick up again.

Impinj's GAAP profitability was inconsistent, but its annual non-GAAP net income still grew from $3.7 million in 2016 to $6.4 million in 2021. Analysts expect its adjusted EPS to more than double this year, and grow another 45% in 2023 as its revenue growth accelerates again. Impinj's stock isn't cheap at more than 100 times forward earnings, but it could certainly grow into those valuations as it ships more tags and readers worldwide.

3. Monday.com

Monday.com's cloud-based platform enables companies to produce their own custom work management and automation apps. It also provides prebuilt "recipes" for automating common tasks, and it can be integrated directly into dozens of popular enterprise apps like Microsoft's Teams and Adobe's Creative Cloud.

Two major tailwinds drive the Israeli company's long-term growth. First, it can help large companies cut costs and streamline their operations by automating tasks, improving their digital workflows, and eliminating unnecessary positions. Second, the ongoing shift toward remote and hybrid work will force many older companies to digitize their businesses.

That's why Monday.com has generated explosive growth since its IPO last year. Its revenue surged 106% to $161 million in 2020 and grew 91% to $308 million in 2021, and it expects an additional 62%-63% growth this year. It served 152,048 customers at the end of 2021 -- representing 34% growth from 2020 -- and its net dollar retention rate (its year-over-year revenue growth per existing customer) stayed above 125% in the first half of 2022.

Those growth rates are impressive, and its stock doesn't seem too expensive at 10 times this year's sales. Unfortunately, it still isn't profitable by GAAP or non-GAAP measures -- and all that red ink will continue to keep the bulls at bay as interest rates keep climbing. But for investors who believe Monday.com's profitability will improve as economies of scale kick in, it could be a great long-term buy at these depressed levels.