1. Qustodio

A full suite of parental control tools to keep your kids safe online

Operating system: Windows, Mac, Android, iOS, Kindle, Nook

Most parental control software is aimed at Windows users, but Qustodio (think 'custodian') is also available for Mac, Android, iOS, Kindle and Nook.

The free version is one of the most comprehensive parental control apps around, enabling you to set rules and time schedules, block pornography and other unsuitable content. If you go for the paid-for version, you'll also get SMS monitoring, social media features and per-app controls.

Its raft of features and support for a wide range of platforms make Qustodio the best free parental control software, but there are some other excellent free programs available, some of which may be better suited to your individual needs as a parent. Read on for the rest of our top choices.

2. OpenDNS FamilyShield

Block domains on your whole home network at router level

Operating system: Windows

FamilyShield is a free service from OpenDNS. Its parental control tools automatically block domains that OpenDNS has flagged under the headings "tasteless, proxy/anonymizer, sexuality, or pornography".

One of the big pluses here is that while FamilyShield can run on PCs and mobile devices, you can also apply it to your network router and filter all the traffic that passes through it – it's just a matter of changing the DNS server numbers in your control panel.

This has the happy benefit of improving DNS lookup speeds on some ISPs. By filtering everything at the router level, every device on your network benefits from the filters. For more options, there's also a premium service available.

3. KidLogger

Detailed activity logging, including apps used and keystrokes

Operating system: Windows, macOS, Linux, Android, BlackBerry

Nothing gets past KidLogger. This free parental control software not only tracks what your children type and which websites they visit – it also keeps a record of which programs they use and any screengrabs they take.

If you're concerned about who your kids might be talking to online, there's even a voice-activated sound recorder. If your children are a little older and more responsible, you can pick and choose which options to monitor and give them a little privacy.

The free software only covers one device and lacks some of the sneakier features of the premium editions (including silent monitoring of WhatsApp conversations and the ability to listen to Skype calls), but it's still a well-rounded tool if you're concerned about your kids' safety.

4. Spyrix Free Keylogger

Find out what your kids are typing, and if they might be in trouble

Operating system: Windows

Keyloggers have something of a bad reputation online, as they're often used by crooks hoping to capture passwords and bank details, but they can be a force for good too, and Spyrix Free Keylogger enables you to see what your children have been up to.

Although it's dubbed parental control software, the free version of Spyrix really a monitoring program; it doesn't stop the kids getting up to no good, but it does let you see exactly what they've done. If you want content blocking too, premium subscriptions start at US$59 (about £45, AU$75).

The absence of filtering means Spyrix might not be the best choice for younger kids' computers, but it may be useful for older children if you suspect online bullying or other unpleasantness.

5. Kaspersky Safe Kids

Parental control software for all devices

Operating system: Windows, macOS, Android, iOS

Kaspersky Safe Kids is parental control software for all devices – desktop and mobile – with both free and paid-for versions.

The free edition includes a blacklist that prevents your kids seeing inappropriate content online, plus app controls that let you manage app use by time used, age restrictions, and category (if you don't want your kids playing games on a school night, for example). There's also a screen time management tool to help you control overall device use,

The paid version adds more mobile-specific features, including a battery tracker so you can see if your kid's phone is about to go flat, leaving them without a way to contact you. You can also keep an eye on their location with GPS tracking, manage their social media use, and receive real-time alerts if they visit websites they shouldn't or leave a pre-defined 'safe' area.

We found that it took longer than usual to log into a Windows account when Kaspersky Safe Kids was running on a Windows 10 PC, so this is worth bearing in mind if your kids' PC is a little on the slow side already.

Other Apps to Consider

Wondershare Famisafe

A premium parental control app for mobile devices, Famisafe can be installed on up to 30 devices per account. It features all the usual tools for keeping kids safe, including setting time limits and blocking inappropriate content, but can also detect potentially inappropriate photos and text messages, block games, and monitor your kids' whereabouts with GPS and geofencing.