The app Acorns rounds up small purchases. If you buy a $2.50 coffee, it rounds up the price to $3 and invests the 50 cents in a portfolio of low-cost exchange-traded funds.
You can choose the level of risk, from conservative to aggressive. According to Money, one user saved an extra $250 in a few months without noticing any difference.
TaxCaster by Intuit TurboTax can estimate your income taxes. It can do a side by side comparison of your tax obligation estimate with the 2017 and 2018 tax laws, to see how tax reform might affect you.
It can also help you make other tax-related financial decisions such as realizing capital gains, all from your smartphone.