Uh-oh - you see a crack in your foundation?
While a vertical foundation crack may not be as urgent as a horizontal one, that doesn't mean you are in the clear.
As with any crack in concrete anywhere you need to be vigilant. Measure it and inspect it on a regular basis to make sure it is not getting longer or wider.
If you have a horizontal crack in your foundation - so it is probably bowing in - then you have big potential trouble and it needs immediate attention.
So what about fixing a stable vertical crack?
First know that water was probably instrumental in making the crack, or helping to grow the crack, and no matter if you caulk it or use hydraulic cement to repair the crack, if you don't take care of the water intrusion the repair is doomed to fail.
Of course, the water intrusion goes back to basic things like, are your gutters clean, does water naturally run away from your foundation, and do you have a working french drain around your home.
I would be more inclined to contact either a structural engineer or a foundation expert for an inspection. I would then use their opinion to begin my repairs.