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Hey, if you can get a smartphone the size of your wallet (and even use it as a wallet) why don't use mobile app technologies to fill that wallet with money?

That's the promise and potential of money-making mobile apps in 2019. There is no shortage of money-making mobile apps on the technology landscape, and the real beauty part is that most (but not all) of those apps come free of charge.

Whether it's using a mobile app to get a freelance gig or one that gives you cash back on purchases, money-making mobile apps are an easy and efficient way to beef up your personal bottom line - one click at a time.

Here are 20 money-making apps that, when used as directed, can add some luster to any stale bank account.

20 Best Money-Making Apps of 2019

1. Ebates

This mobile app, which has issued $1 billion to its users since it was rolled out in 1999, is a discounter's dream. Use it to take advantage of instore apps on your phone and get cash back on certain purchases. Can 2,500 retailers listed on the app be wrong?

2. Swagbucks

If you're a passionate taskmaster then Swagbucks is for you. The app pays out users who complete short and sweet tasks. It could be a quick survey or writing a product review, but whatever the task, once it's completed you earn points that can be turned into cold hard cash or a gift card by Swagbucks. Your first task? Sign up now and earn $10 from the app.

3. Ibotta

If you're into those arm-length-long paper receipts you get from CVS ( CVS - Get Report) , give Ibotta a try. The mobile app allows you to earn bucks by getting cash back from the retailer after you purchase a product. Buy select items on the app and earn a cash bonus. You can also earn $10 on the app just for signing up.

4. Shopkick

This mobile app also uses the accumulated points model, where you earn points by buying and recording certain products from hundreds of retailers, like Amazon ( AMZN - Get Report) and Walmart ( WMT - Get Report) . Just scan the receipt and the purchase will be recorded on the app, and the points you've earned will appear in your account. Turn the points in for gift cards from major retailers.

5. Acorns

Regular stock market investors can add to their portfolio value with Acorns. The app takes spare change from your regular spending activity by rounding up the purchase price and steering that spare change into stocks and funds selected by Acorns. That means no more pennies or dimes in your pocketbook or car console. Instead, it goes toward the stock market with investments made, albeit in small amounts, in your name.

6. Pinecone

That's right, from Acorns straight to a Pinecone, a mobile app that specializes in consumer surveys. Users can sign up and complete surveys based on consumer products and services. Once the survey is in the books, the user gets paid $3 for about 10 to 15 minutes of work. Payments are made via PayPal, ( PYPL - Get Report) once you're up and running on the site.

7. Dosh

This mobile app offers cash rewards for regular shoppers who use Dosh to earn cash back when shopping at participating retailers. You do have to add your bank payment card, debit or credit, to your Dosh account before you can start earning cash. You'll be paid in "Dosh dollars", which amounts to a percentage of the purchased based on the cashback amount.

8. Zap Surveys

This survey-based app also pays users to take surveys - they'll pay a minimum of $1 for each survey completed. If, for some reason, your survey isn't approved, you'll still earn a discounted cash reward. Cash in for a PayPal or Amazon gift card once your account hits $25.

9. TruNow

On the road a lot? Take advantage with this mobile app when you gas up your vehicle. TruNow uses a geo-map feature to let you know where the closest participating gas stations are located. Go there and fuel up, scan the receipt, and earn cash back on the transaction. Cash back percentages vary, but 2% or 3% of the total purchase is common. Get paid via PayPal, or earn enough money to buy free gas using the app.

10. Makeena

If your lifestyle leans toward the green side of the aisle, then give Makeena a fair shake. This eco-friendly app provides cashback rewards when you make environmentally-friendly purchases, like a healthy selection of fruit or smoothies or biodegradable trash bags from approved retailers. Make the purchase, scan your receipt on the app, and earn cash rewards via points accumulated, via Venmo or PayPal.

11. MyPoints

One of the most seasoned money-making app experiences comes from MyPoints, which has a two-decade track record of helping consumers earn cash online. Primarily, it does so for a hodge-podge of tasks, like completing surveys, reviewing products, viewing company emails for accuracy and value, and other business-oriented chores. You can also earn cash-back rewards with purchases from select retailers. Get paid via gift card or through PayPal.

12. Foap

This mobile app caters to the shutterbug among us. It enables you earn cash by selling your photos and videos on the app or website. It's a fair proposition, as Foap will split the proceeds of any sale on a 50-50 basis. Sell a photo of your cat for $15 and earn $7.50 on the transaction.

13. Google Opinion Rewards

Google ( GOOGL - Get Report)  offers a survey-taking app that pays users to complete company surveys. You won't get rich - it pays up to $1 for the completed survey, but the surveys are easy and quick to complete and you get paid through PayPal.

14. Slidejoy

This creative app works like a Madison Avenue advertising agency, with a smartphone twist. Once you download the app, you'll start viewing advertisements on your phone's screen when it's locked. Slide for more information, or for more ads, and get paid points (called "Carats") that are redeemable via PayPal or through gift cards.

15. Sweatcoin

If you're a big cryptocurrency user, Sweatcoin will reward your physical activity through the payment of digital currencies. For example, every 1,000 steps you take nets you 0.95 Sweatcoins. Walk 10,000 steps and you'll earn 0.95 Sweatcoins. Digital currencies do grow in value, so your take may grow in value as you use the app.

16. Stash

Like Acorns, this mobile app helps you earn money from the financial markets. Sign up and pop in your preferred investments (i.e., technology stocks, international stocks or consumer goods stocks) and Stash creates an investment portfolio just for you. Hook Stash up to your bank account and the app will reroute a few dollars toward your favorite stocks and funds, and as history suggests, will help grow your investment portfolio even more.

17. Fluid Market

This mobile app allows car, SUV and truck owners to rent out their vehicles that would otherwise sit idle. Owners can rent their vehicles by the hour, day, or week. The app also allows users to rent out household items like power tools, boats or bicycles. Users say they've made thousands of dollars per year using the app, with minimal stress.

18. Rover

If you love dogs, fresh air, exercise, and money, then Rover is worth a look. The app links pet owners with pet sitters, with the latter charging up to $30 for a 30-minute dog walk, or up to $100 a night for an overnight visit. Users say that with multiple clients, they can make hundreds of dollars a week on a part-time basis.

19. Instacart

In general, people view going to the grocery store as a hassle, and that's where Instacart enters the picture. The mobile app allows users to do the grocery shopping for those who don't want to, and deliver the goods right to their front door. Pay ranges are wide open - it really depends on how many trips you make and how many groceries you deliver, but users say they earn about $15 to $20 an hour, not counting tips.

20. BookScouter

If you're a book lover but have more books than your home can handle, BookScouter will help you sell unwanted books for a decent price. Just post your book for sale and BookScouter will compare prices for you among dozens of book buyers and rank them by price. That way, you're pretty much guaranteed to get the best price possible. The app is especially helpful to cash-strapped college students who can sell their textbooks for some much-needed cash.

It's never too late - or too early - to plan and invest for the retirement you deserve. Get more information and a free trial subscription to TheStreet's Retirement Daily to learn more about saving for and living in retirement. Got questions about money, retirement and/or investments? Email Robert.Powell@TheStreet.com.