Stock market investing can be an excellent way to build wealth over time. Putting hard-earned cash to work can help investors grow their nest egg for retirement, put kids through college, and/or reach other financial goals.

Investing in growth stocks can be an excellent way to build wealth in the stock market. These are stocks of companies that are expected to achieve faster-than-average growth. That growth can help them generate big returns in the process. This strategy isn't without risk, of course. Growth stocks can be quite volatile because of investors' lofty expectations.

If you're OK with these risks, three solid growth stocks with massive long-term potential you might want to consider are Roku (ROKU 0.61%), The Trade Desk (TTD -1.06%), and Kinsale Capital (KNSL -7.12%). Here's why.

1. Roku

Roku is a pioneer in streaming television and dominates this market in North America. According to Pixalate, Roku has a 50% market share in North America, well ahead of Apple and Samsung, which combined have a 34% market share. 

Roku's growth has been staggering. Since 2017, Roku's user base, measured by active Roku accounts worldwide, has gone from 14.2 million to 71.6 million. That's a compound growth rate of over 30% annually for those keeping score at home. The company has benefited from shifting consumer trends away from traditional television toward connected-TV streaming, and that trend doesn't seem to be slowing down any time soon.

As customers flock to connected TV, advertisers have followed suit. According to GroupM, connected-TV ad revenue is expected to grow 13% this year to nearly $26 billion. Over the next five years, it forecasts revenue to grow at 10% annually. 

In the past year, Roku struggled with a slowdown in ad spending and ballooning expenses, taking it from a net income of $242 million in 2021 to a net loss of $498 million. Looking forward, Roku has an excellent opportunity to continue improving its platform to make it more advertiser-friendly. It should also benefit from an improving advertising landscape, and recent price hikes from several premium services could give it an added boost.

At nearly $75 per share, the stock still trades down almost 85% from its all-time high -- making this growth stock with massive long-term potential an appealing buy today.

2. The Trade Desk

The Trade Desk is another thriving business in the changing advertising-media landscape. That's because it provides a marketing platform for digital-ad buyers, connecting buyers with ad space across online media channels and formats.

The company stands out because it helps clients optimize their advertising budgets by precisely targeting customers. The company has enjoyed explosive growth, with revenue increasing 31% annually over the last five years. 

While its growth has been excellent, it still has a massive market opportunity in front of it. The Trade Desk is a leader in programmatic advertising, a market expected to grow rapidly in the coming years. According to a report published by Research and Markets, the programmatic advertising market is expected to grow to $19 billion by 2027, representing an annual growth rate of 21%. 

Management for The Trade Desk believes the company is still in the early stages of tapping into a $135 billion market for digital media. But it has its sight set on an even bigger market -- total global ad spending, which is a market of about $830 billion. 

The Trade Desk recently launched its Kokai platform to continue building on its position in digital advertising. This platform leverages artificial intelligence (AI) to help advertisers optimize ad impressions to reach their target audience. Kokai builds on The Trade Desk's value proposition by helping advertisers get the most bang for their buck, leveraging data, and providing insights into how they can better reach their customers. 

The company may face near-term headwinds, especially if the U.S. were to enter a recession, which could lead to further cuts in advertising budgets. However, its business has demonstrated strong momentum, which seems likely to continue considering where advertisers are moving long term. Given The Trade Desk's platform and impressive growth, now could be a good time to nibble on some shares with an eye toward adding more if it dips from here.

3. Kinsale Capital

Kinsale Capital writes insurance policies on hard-to-place risks or policies that traditional insurers don't typically cover, and has done an excellent job. These policies, called excess and surplus (E&S), can be highly profitable for companies with the knowledge base and ability to accurately assess the risks of these unique policies.

Kinsale has done an excellent job balancing risk and reward in its policies. Since going public in 2016, its revenue has grown tenfold, while its diluted earnings per share have grown 643% at industry-beating profit margins. As a result, the specialty-insurance company's stock price has skyrocketed by 2,000% since its initial public offering (IPO).

Kinsale is currently benefiting from market conditions that specifically favor E&S insurers. Right now, the insurance market is in a "hard market," so demand for insurance is outpacing supply. As a result, insurers can raise prices and be more selective about the policies they'll cover. This favors E&S insurers the most because they can be highly selective and focus on those policies with the highest margins.

Long-term trends favor Kinsale, too. According to a report published by Straits Research, the global specialty-insurance market is expected to grow from $81 billion in 2021 to $179 billion by 2030 -- representing a 9.3% annual growth rate. Kinsale Capital's impressive growth history combined with favorable tailwinds to its business make it another growth stock with massive long-term potential you can buy today.