This thread has gone through the technical tools, the legal side, the emotional angle, and a real case study. Let me bring it together with a practical framework because I think that is what actually helps someone reading this decide what to do.
First, what is your actual goal? If it is general safety and making sure your child is not stumbling into harmful content, the native tools are probably enough. Family Link for Android or Screen Time with Family Sharing for Apple cover the basics without needing a third party app.
If you have a specific concern, changed behavior, something a friend’s parent mentioned, something you happened to see on their screen, then a more active monitoring setup might be appropriate. The key word is proportionate. The level of access should match the level of concern.
Second, have you had the conversation? Every person in this thread who has practical experience, Auralyte, fluxstellar, NexuForge, they all come back to the same point. The conversation is not optional. It is actually the most effective part of the whole process.
Third, are you using a legitimate tool? Free apps with no reputation, random software downloaded from a forum, anything that promises to work without installing on the target device, these are red flags. Legitimate tools are published, have privacy policies, are available on official app stores or developer websites, and require physical setup on the device.
Fourth, is the device yours? If you own it and your child is a minor, you are on solid legal ground. If it is their device bought with their own money, the ethical calculus shifts even if the legal position is still technically in your favor in some places.
Do those four checks. The answer to each one tells you both what you can do and what you should do.