Is there a free parental control app?
Yes, some products have a free tier, including Google Family Link. Skie is a paid product, with pricing on request, and it does not have a free plan. The trade is that Skie runs as the Android device owner, which is why a child cannot uninstall it or reset around it.
Free options exist, and for some families they are enough. Google Family Link is free and can approve apps, set times and show location. Several other tools offer a free tier with fewer features.
The difference to weigh is how hard the controls are to remove. A free app that a child can uninstall in a minute may cost you more in worry than you saved. That is not true of every case. A young child who does not know how to look for settings is a different matter from a fourteen year old with a group chat full of tips.
Skie is software for parents, schools, hostels and organisations, and it is a paid product. We do not publish a price list. Pricing is on request, and it does not include a phone, because you use a phone or tablet you already own.
There is a cost beyond the software that is honest to mention: setup takes a one-time factory reset of the device, and the first time takes some care. Once done, you manage everything from a web dashboard.
If budget is the first question, start with your biggest worry. If the worry is a child removing or bypassing controls, compare a free tool against Skie on that point only. If it is location for a teenager who cooperates, a free tool may serve you fine.