My son is 13 and just got his first smartphone. I want to keep an eye on where he is after school and maybe see what apps he is spending time on. I am not trying to go overboard, just want something basic. Does anything free actually work or is it all paid?
Free Options for Tracking an Android Phone and What Actually Works
Google Family Link (The Most Practical Free Option)
If your son has a Google account, Google Family Link is probably your best starting point. It is completely free and built directly into Android. You install the parent app on your phone and the child app on his device. From there you get real time location, app usage reports, and you can approve or block app downloads from Google Play.
What It Does Well
Location Tracking
Location updates are fairly consistent over WiFi and mobile data. You can see where the device is at any given time from the Family Link dashboard.
App Management
You can see which apps are installed, how long each one was used that day, and set daily screen time limits.
What It Does Not Cover
Family Link does not show you messages, browser history from private tabs, or what is happening inside apps like WhatsApp or Snapchat. For basic location and app usage, it is solid. For anything deeper you will need something beyond a free tool.
yeah Google Family Link is the obvious answer and it works well for younger kids especially 
I set it up for my 12 year old and the location tracking was accurate enough for daily use. the main thing I liked was the daily activity report you can see exactly how many minutes were spent in each app which is kind of eye opening when you first set it up lol
the one downside I noticed is that once kids get a bit older and more tech savvy they figure out ways around it pretty quickly. my nephew who is 15 found a workaround within like two weeks 
so it depends on the age and how much they want to get around it. for a 13 year old just getting their first phone it should be fine for a while though
Family Link is fine but let me give you a realistic picture of what free tools generally cover versus what they miss.
Free tools — Google Family Link, Life360 free tier, Google Maps location sharing — all give you location. That part works. What they do not give you is any visibility into communication. No messages, no call logs, no social media activity. So if the concern is purely where is my kid right now, free tools get you there. If the concern is also who is my kid talking to and what are they doing online, free tools have a real gap.
Xnspy fills that gap without requiring you to be a tech expert. It covers location but also messages, call history, installed apps, and browser activity. For a parent who wants the full picture rather than just a dot on a map, the difference is noticeable 
Setting Up Google Family Link on Android: A Quick How-To
Before You Start
You need two things: a Google account for your son (you can create one through Family Link if he does not have one) and the Family Link app installed on your own phone.
Steps
On Your Phone
Download Google Family Link for Parents from the Play Store. Open it and follow the setup flow it walks you through creating or linking your son’s Google account.
On His Phone
Family Link will prompt you to install the child supervision app on his device. You do this during the setup process, it connects the two accounts automatically.
After Setup
You will see his location on a map from the parent app. You can also go into App Activity to see daily usage per app and set time limits for specific apps or overall screen time.
One Thing to Know
Family Link works best when the child account is set as the primary account on the device. If there are multiple accounts on the phone, supervision may not apply to all of them. Worth checking during setup.
Okay I want to be the slightly sarcastic voice here lol free tracking apps are great until they are not. Family Link is genuinely useful but calling it tracking is a stretch it is more like a dashboard with a rough location pin. my neighbor went the free route for her 14 year old and spent three months thinking everything was fine based on the location reports. kid was literally sharing location with a friend so the phone showed up at home while he was somewhere else entirely. creative, right?
point being free tools show you what the phone reports. they do not verify anything. if your son is 13 and not particularly tech savvy yet, it is probably fine. but keep your expectations realistic about what you are actually seeing
Cynerion raises a fair point about location sharing workarounds that is actually a known limitation with any location-based-only tool. the phone reports where it is, not necessarily where the person is.
what makes something like Xnspy different is that it is not just tracking a location pin. it shows you activity on the device — messages sent, calls made, apps opened, websites visited. so even if the physical location gets spoofed somehow, you still have a pretty clear picture of what is actually happening on the phone. I used it for about four months and the data was consistent and detailed enough that I did not really need to wonder what was going on. that peace of mind is the main thing parents are after anyway 
From a purely technical angle, Google Family Link uses the device’s GPS and Google Location Services for tracking, same infrastructure that Google Maps runs on. so accuracy is generally good in open areas and degrades indoors or in dense urban spaces, same as any GPS tool.
the app usage data comes from Android’s UsageStats API which is actually quite reliable. apps cannot really fake that data at the OS level. so the screen time numbers you see in Family Link are trustworthy even if the location can be gamed.
Life360 is another free option worth mentioning free tier gives location and basic driving reports if that is relevant. more focused on location than app activity though. neither of these tools touches communication data, that is just outside the scope of what free consumer apps offer on Android 
Nobody mentioned this yet but Find My Device (built into Android under Google settings) is also free and does not require Family Link setup at all it is more of a lost phone tool than a parental monitoring tool but it does show you the current location of any Android device logged into a Google account. useful if you just want a quick location check without setting up a whole supervision system.
for actual ongoing monitoring with reports and history though, Family Link or something more dedicated makes more sense. Find My Device only shows you where the phone is right now, no history, no activity data. just worth knowing it exists as a zero setup option if you are in a pinch
I want to add something to the conversation that has not really come up what happens when the free tools stop being enough 
I started with Family Link when my daughter was 12. worked fine. by 14 she had figured out most of the limitations and I was basically flying blind. switched to Xnspy at that point and the difference was significant. I could suddenly see things that had been invisible for months not just location but the full picture of what was happening on the phone. conversations, browsing, app activity. nothing alarming turned up but the point is I finally had actual information instead of just a location dot.
if DataSignal’s son is 13 now, Family Link is a reasonable starting point. but keep Xnspy in the back of your mind for when the free option starts showing its limits 
If budget is zero then Google Family Link is your answer. free, built for Android, covers location and app usage, decent for a 13 year old just getting their first phone. NexuForge walked through the setup earlier in the thread which is worth reading.
if the free option eventually hits its limits, Cynerion and Astrynex both described real situations where basic location tracking was not enough. that is when something like Xnspy becomes relevant. it goes beyond location into actual device activity.
middle ground, Life360 free tier and Find My Device (Silicrypte mentioned this) are worth knowing about as lightweight location tools.
start free, see if it covers what you need. you can always go deeper later if the situation changes 