The top 4 investing apps to help newbies and experts build their wealth from anywhere

Investing apps have grown in popularity in recent years and for good reason: Just about anyone can get access to the stock market with just a few taps on their phone.

For beginners, investing apps also serve as an affordable and accessible way to start building their wealth. The good news is there are many options to choose from.

To help you find the right app for your needs, CNBC Select reviewed over three dozen apps offered by robo-advisors, fintech start-ups, big banks and traditional brokerage firms. We ranked the top four apps with a focus on the investor experience level and answered frequently asked questions about investing apps. (See our methodology for more information on how we chose our top picks.)

Who's this for? Betterment is a pioneer in the robo-advising space, so it's likely you've heard the name before. It's a good choice for those who want to be hands-off with their investments, though more advanced investors have the option to customize through flexible portfolios.

The Betterment Portfolio is made up of low-cost, diversified ETFs. Users cannot buy individual stocks or invest in individual funds, so if that's what you're looking for, consider another app on this list.

There is no minimum balance required to invest with Betterment, and the annual account fee is a low 0.25% of your fund balance. Investors with a balance of $100,000 can upgrade to the premium plan, which gives you access to real-life financial advisors for an annual fee of 0.40% of your fund balance.

Betterment's app is available to download for free in both the App Store (for iOS), where it has 4.8/5 stars, and on Google Play (for Android), where it has 4.6/5 stars at the time this article was written.

Who's this for? Acorns is a financial app that gives you access to a robo-advisor, IRAs and even a checking account. It made our list because it's a good choice for novice investors looking to start small through micro-investing.

Micro-investing simply means you're investing small amounts of money in the market consistently so that over time your contributions add up. It's a good strategy for newbies who want to dip their toe into the investing pool before diving all in.

Acorns allows users to micro-invest using the Acorns' Round-Ups® feature, which takes users' spare change and puts it into diversified ETFs. Users link their credit or debit card account to their Acorns account, and the app will do a sweep of the accounts when purchases are made to round up the costs to the nearest dollar and then invest the difference.

The spare change collected from your linked cards are set aside until you hit a $5 threshold, at which point is then transferred into your Acorns Invest account. According to Acorns' website, the average user invests more than $30 per month through the Round-Ups feature.

You can also set up a recurring transfer (daily, weekly or monthly) from your linked bank account to your Acorns investment accounts starting at as little as $5 a month.

The Acorns Invests account is a robo-advisor, which suggests managed portfolios (made up of various ETFs) based on an investor's risk level. Investors cannot buy or sell individual stocks through Acorns.

Acorns offers two plans:

1. Personal plan for $3 per month: The Personal plan includes a checking account, investment account and retirement account.
2. Family plan for $5 per month: The Family plan includes the three accounts that you get with the Personal plan, plus additional investment accounts for your kids.

While the Acorns Round-Ups feature is a great way to get started investing, it's important to make sure you're putting away enough each month to justify the fees. At $3 a month, the fee can quickly eat up a big chunk of your returns if you're only investing a few bucks a month.

Acorn's app is available to download for free in both the App Store (for iOS), where it has 4.7/5 stars, and on Google Play (for Android), where it has 4.3/5 stars at the time this article was written.

Disclosure: NBCUniversal and Comcast are investors in Acorns.

Who's this for? Robinhood was the first on the investing app scene to charge no commission for users to buy and sell stocks, which prompted many other brokerages to eventually follow suit. Like the other apps on this list, Robinhood also has no minimums to open an account and users don't need to reach a minimum to start investing, either.

Investors can easily make stock, options, ETF and cryptocurrency trades, but it doesn't offer mutual funds and bonds, so you may need another investing app to better diversify your portfolio.

Investors can get access to IPO shares through Robinhood, as well as to commission-free fractional shares so they don't have to buy a entire share if they want in on a pricey, big-name stock.

Robinhood offers investors free rein to completely build their own portfolio, so the platform is arguably best for active stock traders who have done their research and know a bit about how the market works. Newbie traders can get in on the action, but just be sure you're comfortable with the risks.

Robinhood's app is available to download for free in both the App Store (for iOS), where it has 4.1/5 stars (with a whopping 3 million-plus reviews), and on Google Play (for Android), where it has 3.8/5 stars at the time this article was written.

Who's this for? Similar to Robinhood, Webull offers commission-free trading on stocks, options, ETFs and crypto, with no minimums required. Users also have access to IPO and fractional shares.

Webull currently offers IRAs (traditional, Roth and rollover) so users can manage their retirement funds along with their stocks all in one place.

Webull offers users a customizable desktop version of its platform if you prefer to trade on a bigger screen and investors have extensive extended trading hours before and after the market closes: 4:00 a.m. to 9:30 a.m. ET and 4:00 p.m. to 8:00 p.m. ET, Monday to Friday.

Webull's app is available to download for free in both the App Store (for iOS), where it has 4.7/5 stars, and on Google Play (for Android), where it has 4.4/5 stars at the time this article was written.

The best investing app for you will depend on your investment style. Do you want one that does the work for you, or would you rather be in control? Do you want a passive portfolio made up of lower risk funds, or would you rather build an active, riskier portfolio consisting of individual stocks?

Those wanting a more active approach to investing may opt for an app like Robinhood (just make sure you've done your research beforehand). Meanwhile, those looking to just put their investments on autopilot and forget about them may benefit more from a robo-advisor like Betterment.

Keep in mind that not all apps offer the same investment assets to choose from. For example, Acorns only offers ETFs, so if you want to trade individual stocks, this app wouldn't be the best fit. Make sure you do your research and understand everything the app offers (and doesn't offer) before you sign up.

Our top-rated investing apps help investors of all stripes — no matter where they are on their investing journey — build wealth on the go. Newbies may want to start small by micro-investing through an app like Acorns, which invests users' spare change. Beginner and intermediate investors alike can automate their investing using a robo-advisor app like Betterment, while more seasoned investors can trade stocks and options with Robinhood or Webull.

At CNBC Select, our mission is to provide our readers with high-quality service journalism and comprehensive consumer advice so they can make informed decisions with their money. Every investing app review is based on rigorous reporting by our team of expert writers and editors with extensive knowledge of investing products. While CNBC Select earns a commission from affiliate partners on many offers and links, we create all our content without input from our commercial team or any outside third parties, and we pride ourselves on our journalistic standards and ethics. See our methodology for more information on how we choose the best investing apps.

CNBC Select analyzed over three dozen apps offered by robo-advisors, fintech start-ups, big banks and traditional brokerage firms. When ranking our top picks, we looked at the apps' pricing (trading costs, minimums and account fees), mobile features, educational resources, user reviews and ratings. We also took into account the various investment products that each app offers its users.

Each investing app on this list has at least a 4.1 star rating (out of 5) in the App Store (for iOS) or on Google Play (for Android), with a sizable number of user reviews.

Your earnings through an investing app are subject to fluctuations of the market, and they depend on any associated fees, as well as contributions you make to your account. There are no guarantees you will earn a certain rate of return or current investment options will always be available.

To determine the best approach for your specific investment goals, speaking with a reputable fiduciary investment advisor is recommended.

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Disclosure: NBCUniversal and Comcast Ventures are investors in Acorns.