It feels like the whole thing was a waste of a Sunday. It was not, and the fix is one tick box.
What is actually happening
Chrome does not run extensions in private windows unless you say so. Every extension has a setting called Allow in Incognito, it lives on that extension's details page, and it arrives switched off.
The reason is sensible. A private window is meant to be a session that keeps nothing and tells nothing, and extensions can read pages, so Chrome makes you opt each one in individually rather than assuming. The consequence for a parent is blunt: unless you have gone and ticked that box, a private window is a browser with none of your rules in it.
Which means nothing was bypassed here. There was no lock at that boundary to defeat. Your child opened a window where the blocker was never running, discovered the site opened, and drew the obvious conclusion — that private mode is the way past this — when in fact the tool had simply been excused from the room.
That distinction matters, because it changes what you do next. You do not need a cleverer blocker. You need to change one setting, once, per computer, and the behaviour disappears.
The check takes a minute and you should do it now rather than take anybody's word for it. Open the extensions page, find the extension, open Details, and look for the Allow in Incognito switch. Whatever state it is in is the state your rules were in every time a private window was open on that machine. Then turn it on, open a private window, and try the blocked site. You should get the block page.
The three places this goes wrong
1. Nobody ticked the box. The overwhelmingly common case. It is off by default, no installer mentions it, and the failure it causes looks exactly like a bypass.
2. You ticked it on one computer. The setting belongs to that extension in that profile on that machine. A second laptop, or a second profile on the same laptop, starts unticked again, and you will not be reminded.
3. You are relying on the history to tell you. Private windows keep no history by design, so a parent who checks the history sees a quiet afternoon and concludes nothing happened. The absence of a record is not the absence of an afternoon.
How to make it hold
Turn Parentech on for private windows: extensions page, Details, Allow in Incognito. Do it on every computer and in every profile you have installed it in, and take thirty seconds afterwards to check the block page appears in a private window. That is the whole repair.
Then keep the rest of it locked. Changing the list, opening a blocked site or ending a class early all need your six-digit PIN, and the dashboard locks the moment it is closed. Search words are stopped the same way in a private window as anywhere else once the box is ticked, so the search that would have found the site is not a route back in either.
The floor underneath all of this is still the computer account. A child with administrator rights can remove the extension outright, which no extension can prevent, so give them a standard account without those rights and keep the administrator password to yourself.
The part that needs you not to be there
There is a version of this page that ends at the tick box, and it would be a slightly dishonest one. Ticking it takes ten seconds. Keeping it ticked, on every machine, for a year, is a different problem.
Settings like this rot quietly. Chrome gets reinstalled on the old laptop. A new profile appears. The school hands over a different machine in September and you set it up in a rush on a Sunday night. Every one of those events resets this to off, and none of them announces itself. You find out weeks later, the way you found out this time.
What helps is not another switch. It is having every Chrome in the house running the same rules from your account rather than each one being its own separate project, and being able to look, from wherever you are, at what a computer is actually enforcing — then change it from parentech.app on your phone, with the change landing within half a minute.
The straight version: everything on this page works free on one computer, set at that computer with your PIN. What the family plan buys is the other computers, a different set of rules on each, and your phone. If there is one laptop and you are usually beside it, the free tier is genuinely the whole product.
What this still does not reach
- A profile you have not installed it in. A new profile starts empty, and its private windows start empty twice over.
- A phone or a tablet. Parentech guards Chrome on the computer it is installed on.
- A child with administrator rights. They can remove the extension, and no extension anywhere can stop that.
Questions parents ask
Does a private window hide what they did from Parentech?
There is nothing to hide from. Parentech does not collect what was visited on any kind of window — rules are checked on the machine and nothing about their browsing leaves it. The only thing a private window changes is whether the rules run at all, and that is the box.
Should I just stop them using private windows?
You do not need to. With the box ticked, a private window behaves like any other window: blocked sites do not open, blocked searches do not run. It stops being a route and goes back to being a feature.
They turned the box off again.
Then they have administrator rights on the computer, or they have your PIN. Deal with the account first; it is free and it takes five minutes, and it is the thing every other answer on this page rests on.
If this is happening to you, one of these usually is too
A new profile beat your blocker · They installed a second browser · They keep unblocking the site
More on how blocking works: Block websites. Free on one computer — what it costs for the rest of the house.