Agree with MDM, and actually prefer Fido to Vanguard because I like their customer service and interface stuff much better.
I have my entire portfolio with Fido, and invest only in their extremely low cost index funds (see MDM's link for the comparisons to Vanguard funds). My company set our plan up so there were zero management fees charged, so it was a super awesome deal. I had the option in my 401k to invest in their Fidelity Total Market Index Fund (FSTVX), so that's where 100% of my 401k contribution went.
Fidelity is a for-profit company, but they also are trying to be tops in terms of customer service and offerings, and because of that, they are constantly improving things like apps, website development, ease of use and being extremely helpful. They have index funds just as good and as cheap as Vanguard, AND better apps, better reps, more perks. They do this in the hopes that you'll be tempted to also invest in some of their managed funds and form a long term relationship with them, but if you stick with the low cost stuff (which is super great) you get the best of both worlds: great customer service and great, low cost funds.
I am not knocking Vanguard, but Fido, if your plan allows you to invest in their index funds and doesn't end up charging you insanely high management fees for the plan administratin, is a stellar offering.