In what has been a relatively uneventful year for tech IPOs, a number of private startups continue to set record valuations in exchange for cheap capital. While few private tech companies have released IPO information, the following seven companies have grown quite rapidly and could prove to be lucrative investment opportunities for public traders.

Uber: After several rounds of funding worth $4.6B, Uber’s $41.2B valuation is the largest on our list. Already the most funded startup in history, Uber is currently in talks to raise another $2B in private funding. With over $6B in private capital, analysts suggest that an eighth round of funding would likely value Uber at over $50B; if such an event occurs, Uber would become the most valuable startup of all time, even surpassing Facebook (FB) prior to its IPO. As such, given its growth ambitions, Uber appears poised for an IPO in the near future.

Snapchat: CEO Evan Spiegel received widespread criticism for rejecting Facebook's $3B acquisition offer in 2013. However, with Snapchat currently valued at $16B, it sure looks like the then 23-year-old Spiegel made the correct decision. To date, Snapchat has raised $1.2B in private funding from both VC firms and tech companies like Yahoo (YHOO) and Alibaba (BABA). Of equal importance, these seasoned veterans are now advising Spiegel on how to generate meaningful revenue from Snapchat’s 100M members. Snapchat’s future profitability relies on how effectively Spiegel, and other company executives, can monetize the app without upsetting its young user base. Spiegel has publicly expressed his plan for an IPO, but has not yet announced a timetable for the offering.

Palantir: Known as America’s most secretive company, Palantir is also one of America’s most valuable startups. Currently valued at $15B, Palantir has enticed investors, to the tune of $1B, by helping the Federal Government identify, track, and kill Osama Bin Laden. Palantir's analytics software also alerted the SEC and DOJ about Bernie Madoff's historic $57 billion Ponzi scheme.  Not only is taking down bad guys good for PR, but it is also profitable. Since 2009, Palantir has received $215M worth of federal security contracts from agencies like the FBI, CIA, and NSA. Moreover, Palantir's analytic program, originally designed to detect fraud for PayPal, has recently proven incredibly adaptable. Palantir's big data software is now used in sectors such as banking, healthcare, and energy. Unfortunately for investors, Palantir’s executives do not currently plan on filing for an initial public offering.

Pinterest: Still a relatively new company, Pinterest is already valued at more than $10B. The social media company just began selling ads and, for the first time, generated revenue in January 2015. Although Pinterest faces stiff competition from established social media companies like Facebook and Twitter (TWTR), private investors see potential in the company’s ability to track users’ interests via its "pin" system. We believe Pinterest's low margin business model makes it a likely upcoming IPO candidate.

Airbnb: Valued at $20B, the popular home-sharing company is already valued higher than publicly traded hotel chains Hyatt (H) and Wyndham (WYN), despite not owning physical rental properties. However, like Uber, Airbnb faces significant legal obstacles, which will be costly. According to Eric Schneiderman, NYC’s attorney general, more than half of Airbnb’s rentals are technically illegal. Hotel groups are also lobbying against Airbnb's ambitions; like the government, hotel conglomerates hope to use America's legal system to stymie Airbnb's expansionary efforts. As such, Airbnb must first resolve its legal battles before issuing an IPO.

Dropbox: The file hosting company reportedly turned down a generous acquisition offer from Steve Jobs prior to its current $10B valuation. Although companies like Apple (AAPL), Amazon (AMZN), Google (GOOGL), and Microsoft (MSFT) have increased their cloud offerings, Dropbox nevertheless continues to attract investors. The company recently released a photo-sharing app and hopes to expand further into enterprise services. The dismal performance of Box after its public offering, which offers similar cloud services, may discourage Dropbox’s IPO plans.

Spotify: The supremely popular music streaming service recently raised $400M, with Goldman Sachs (GS) listed as one of the primary investors. At an $8.4B valuation, Spotify is valued at more than double its publicly traded competitor: Pandora (P). However, Spotify will soon face new competition from Apple, as it integrates Beats Music into its iTunes service. Given this inevitability, Spotify will likely keep from issuing an IPO. Instead, Spotify will observe the public's reception of Beats Music and accordingly adjust its business strategy. Furthermore, to be profitable Spotify must also encourage its users to upgrade to the $9.99 premium service. Of Spotify's 60M active users, only about 15M are premium members.