There are many such online services, most of them free and a Google search away, so I won't make this a list answer, and since you didn't specify what data in particular you're hoping to find, here's one of my favorite satellite trackers with fairly complete position data, ground track display, map options and so on: NASA iSAT (Interactive Satellite Viewer). You might want to allow it to use your location for more convenient display, but it isn't necessary to enable that.
That's for a desktop computer, but if you're hoping to spot satellites (a.k.a. tracking) on the go, then I'd personally suggest installing Sky Map + on your smartphone / tablet (it is free, but there are of course others), because it includes a lot more useful information and has both compass / gyroscope / GPS positioning for easier identification of spotted satellites (it pans automatically) as well as manual panning mode. You can tap on screen to display the toolbar and select objects that you want displayed, or switch to ruby & black monochromatic night mode, if default display is too bright. Satellite information can be updated in settings via an additional download, and all of it is free.
For downloadable data alone (to perhaps include in your own software or import into your database), one of such sites is CelesTrak that includes TLE (Two-Line Element) sets and a Space Track TLE Retriever 3 tool to download Space Track data sets.