Ycharts is a very nice site for stocks and ETFs. It does not have MFs, however.
As Truenorth noted, many sites only show the price history of an equity, which can really understate its return due to omission of dividend, and also realized cap gains for MFs.
As a MF manager buys/sells his stock holdings through a year, he has to declare to his shareholders the dividends, short-term capital gains, and long-term capital gains that he receives in the year, net of the losses of course. These declarations are for tax purposes, and the share holder may or may not want to reinvest them.
As the stocks that he does not trade also appreciate in value, this results in the MF share price going up in value due to unrealized gains.
The return numbers that MFs usually quote are the total returns, assuming that all distributions are reinvested.
In the retirement distribution phase of life, many people plan to live off the dividend and cap gain distributions, and expect or hope that the price increase of the MF share carries enough unrealized cap gains to keep up with inflation. I guess that was the reason for the question by the OP.
Now, suppose that a MF has cap losses instead of gains due to a bad year. Note that when the market drops hard, some shareholders will bail out, and the manager has to sell something to get cash to meet redemption. And that means that he usually sells low against his own wish, and may suffer some loss. The law does not allow passing on that cap loss. The fund can then keep that loss on its book to cancel out future gains.
For more info on tax and accounting issues with MFs, see:
Mutual Funds and Tax Benefits - WSJ.com.