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10 Best Window Locks of 2021 – Sliding Window Lock for Home Security

The locks that come with many windows may not be secure enough to keep burglars out or kids in, and it can be a wise choice to add a secondary lock to be sure.

If you are looking for something that will give you extra peace of mind that your home is safe, here are our top picks for best window locks to help you choose the right solution for your home.


The Best Window Locks on the Market of 2021

1. Defender Security U 9809 Window Locks (Our Top Pick)

Defender Window Locks

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These Defender Security window locks are an affordable way to add an extra level of safety to your windows, whether you hope to keep potential burglars out or young children in.

They are super-easy to install and can be in place in a matter of only minutes – this product is designed specifically for use on horizontally-sliding windows but will work with many single-hung vertically-sliding windows too.

Each lock has an adjustable jaw that is designed to fit just about any vinyl frame from 1/16” up to ½” in width, and when in place, they allow you to either lock the window completely shut or leave it slightly open for ventilation without the possibility of it being opened from the outside.

One of the best things about this system is that it doesn’t require any drilling, screws or anchors, meaning that you won’t have to make any structural alterations to your windows – and for this reason, they are particularly suitable if you live in rented accommodation.

We like the way these locks are also so small and inconspicuous. They have an unobtrusive white finish, and once in place, you will hardly notice them.

It should be pointed out that if somebody was really determined and had the necessary tools – like a bar to prize the window open – it might still be possible to break in through a window.

However, it would take a lot of effort, and most burglars would see these locks in the window and quickly move on to the next place.

For this reason, these locks are an excellent choice for a secondary lock that will add an extra layer of security to your windows. They are inexpensive, quick and easy to fit and are highly effective – and as such, they could be an excellent option to consider.

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2. Lion Locks Aluminum Sliding Door and Window Lock

Lion Locks Aluminum Sliding Window Lock

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If you are looking for a simple solution for keeping your windows safely closed and preventing intruders from gaining access, these versatile locks from Lion Locks could be the ideal choice.

They are suitable for a range of applications, including sliding windows – both vertical and horizontal – as well as sliding doors.

Made of heavy-duty aluminum with an inner lining made of vinyl to protect your window frames, they are sturdy and durable. They will fit on a window frame of up to 3/16” in thickness with the liner in place – or without the liner, up to 3/8”.

Installation couldn’t be easier and requires no tools. You simply clamp them in place using the double thumbscrews to prevent the window from opening. This means you can close the window completely or lock it with a slight gap to allow some air to pass for ventilation.

What we really like about these is how simple and inexpensive they are; however, despite this, they are extremely effective. Once in place, they will make it very difficult to gain access from outside without a lot of effort – plenty to deter most opportunistic burglars.

When you want to remove them, it is just as easy – all you need to do is unscrew them and pull them off.

Perhaps our only complaint might be that the screw handles are a little small, making it a bit difficult to get a good grip when tightening or untightening. Also, some people might find them a bit ugly – but they are small and hardly noticeable, so this is not a huge issue.

Other than these minor gripes, these locks are an excellent option if you want a quick, easy and affordable way of increasing the security of your windows or sliding doors. If that sounds like what you’re looking for, these are sure to be of interest.

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3. Maxdot Adjustable Sliding Window Locks

Maxdot Adjustable Sliding Window Locks

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These Maxdot adjustable sliding window locks are a simple but efficient way of keeping kids inside and intruders out. Each lock is attached to the window frame, and each one features a double-locking system that makes it harder to force them open from the outside.

Since they are made of aluminum alloy, they are sturdy and strong, meaning it is practically impossible to break them by force. Each one also includes a hex key with a plastic yellow handle to make it quick and easy to tighten them or remove them as necessary.

You can use them to lock windows closed – but you can also leave windows slightly open to allow some breeze to pass without compromising your security.

There’s not much to dislike about these keys. However, some people might find them a bit awkward with the detachable keys. For some, it might be more practical to have fixed keys like the Lion Locks version above – although that’s a matter of personal preference.

Apart from that, it’s hard to fault these locks. They are extremely inexpensive and do the job they were designed for perfectly and with a minimum of fuss, so for anyone who wants a quick and easy solution for adding extra security to their windows, they could be an obvious pick.

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4. Onvian Window Locks

Onvian Window Locks

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If you like the sound of the Maxdot locks we looked at above and would like some other options to compare them with, these locks from Onvian are very similar.

They feature the same double-locking system that increases friction, making them more difficult to force open. Installation is super-easy since you only need to attach them to the window frame and tighten to secure the window and prevent intruders from gaining access.

You can tighten them using the keys supplied – but they also work with regular hex keys, meaning you can still use them if you lose the keys that come with them. They are suitable for use with a wide range of horizontal and vertical sliding windows as well as doors.

We also like the way they are made of tough aluminum alloy, making them hard to break and ensuring they will resist rust – these locks should last a long time.

Since they are so simple and effective – as well as inexpensive – it’s hard to find anything we dislike about these locks.

One thing we might point out is that, since they are compatible with regular hex keys, older children might be able to open them if they find a key that fits – you can’t guarantee they will remain shut just by hiding the hex keys that come with them.

However, this is only a small issue. Generally speaking, these locks do exactly what they were designed for, making them another solid option for increasing security in your home for the least amount of money. Another recommended product.

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5. Window and Door Babyproof Safety Lock

Window and Door Babyproof Safety Window Lock

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If you have a baby or young child, you will know how important it is to make sure windows stay shut, preventing them from falling out or going outside unaccompanied. If that is something you can relate to, then this product could be just the thing you need.

This window lock is designed specifically for keeping windows closed for the safety of children – it isn’t designed to keep burglars out.

What we really like about this product is that it’s so easy to install and use. You don’t need any special tools or equipment to fit it – it comes with everything you need for installation, and you just need to attach it to the glass with the heavy-duty industrial-strength tape that’s included.

Once in place, they prevent any kids from opening the windows wider than the locks allow, helping keep everyone safe inside.

These locks are a great product, and we don’t really have any issues with them. The only thing we would point out is that some smarter kids might be able to work out how to open them, which means they need to be positioned high enough to be out of reach of young children.

However, this shouldn’t be a problem for most people, and for us, this is a highly effective lock that should give you the peace of mind that your children won’t be able to fall out of windows. If that’s something you think is important, they’re well worth considering.

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6. Sliding Window Locks

Sliding Window Locks

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Here is another option if you’re looking for a way to prevent sliding windows from being opened – either from outside by unwanted visitors or from inside by kids who you don’t want falling out.

They are made from a strong aluminum alloy that will resist being forced. Using just one per window will do the job perfectly, but since they’re so inexpensive, you could just as easily double up and use two for extra security.

Installation could hardly be easier, and you can have them in place quickly and easily after following three simple steps. You don’t need any tools to fit them to your windows, and everything you need is included in the pack.

Perhaps our only slight complaint here might be that these locks are not the most attractive. Although they are functional and do the job well, we find the part you use to tighten them sticks out too much, making them look a bit ugly.

Having said that, they are hardly big and obtrusive, and most people will probably be able to accept the way they look for the extra peace of mind they offer, so for anyone looking for something simple and effective, these could be worth a look.

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7. Jeacent A/C Security Window Lock Bar

Jeacent A/C Security Window Lock Bar

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If you are looking for a solid and reliable alternative to the kind of screw-on sliding window locks we have looked at above, this bar lock could be an option worth considering.

It is designed to be used with window air conditioning units to prevent the unit being stolen or to stop it falling out of the window – but it could equally be used to prevent people gaining access to your home by sliding open a window.

This bar will fit windows with a minimum size of 7 ¾” up to a maximum of 14 3/8” and effectively stops the window from being opened.

It is made from strong and durable steel that is extremely hard to break or bend, allowing you to rest assured that nobody will be able to force your window open.

The only minor complaint we have is that the Velcro pads it comes with are not particularly effective. However, since they are not essential for safe installation, this is not a big deal, and most people shouldn’t mind too much.

Overall, a simple but very safe option that will greatly increase your security without costing you a fortune. For these reasons, this is a product we like, and it gets a big thumbs-up from us.

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8. Prime-Line F 2588 Sash Lock

Prime-Line F 2588 Sash Window Lock

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While fixed window locks can be a highly effective way of preventing windows from being opened, they all share the same problem – namely that they make it a hassle to open the window fully whenever you wish to do so.

For this reason, for anyone who doesn’t want their window to be semi-permanently shut, this type of sash lock could be a better option.

With a sash lock, you can lock the window whenever you want to prevent the window from being opened from the outside – but when you want to open it, you simply turn it to allow the window to slide open. It is suitable for use on both vertically- and horizontally-sliding windows.

Furthermore, it is also available in three different colors, bronze, silver and white, to allow you to choose the one that goes best with your windows. It is made of diecast zinc for extra strength and durability.

The only downside of this lock is that it requires you to drill holes in the window. However, for a more long-term solution, this is to be expected.

All in all, a good option if you want to be able to lock and unlock your window quickly, allowing you to open and close it whenever you want. If that sounds like the kind of thing you’re looking for, this lock could be ideal.

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9. Reliancer 4 Pack Sliding Window Locks

Reliancer Sliding Window Locks

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While many of the locks we’ve looked at function with regular hex keys, some people might prefer a sliding window lock that works with a unique key – perhaps to keep young children from sneaking out rather than preventing burglars from breaking in.

That said, they will deter potential burglars just as much as any other design, so are effective for that use too.

If that sounds like a familiar situation, these key-operated locks could be the answer you need. They attach to the frame of your windows, much like many other locks – but you need the specific key to open them.

In terms of build quality, they are made of tough stainless steel, making them very strong and resistant to corrosion. They are also bigger and more substantial than many similar options, so they are hard to break.

You won’t have any trouble installing them, either, since they can be fitted to your sliding windows or sliding doors without the need for any tools.

On the downside, a more determined older kid might be able to work out how to remove them – but for younger children, they will be perfectly secure.

In sum, for anyone who wants to keep kids in and burglars out, these could be an excellent option, so this another product that should be on your radar.

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10. Boao Set of 15 Siding Window Locks

Boao Siding Window Locks

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This is a pack of 15 window locks that will allow you to secure all the windows in your home. They are quick and easy to install, requiring no tools, and when you want to remove them to open the window, they’re just as easy to take off too.

Since they are made of aluminum alloy, they are tough and durable. They allow you to close the window completely or leave a slight gap for ventilation while preventing people from getting in or young children falling out.

Another big plus is the price since they are extremely inexpensive. These locks provide a way for you to secure your home and increase security levels for your family without the need to spend a fortune.

One of our only complaints is that they are not particularly attractive – although, at this price, you might only expect something functional rather than anything that looks nice.

Also, you should check the dimensions of your window carefully to make sure they fit before buying as they might not fit all window styles.

Overall, however, these are a great option if you are looking for the least expensive way to secure all the windows in your home. If that’s all you want and don’t need anything that looks pretty, these could be an option worth thinking about.

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Buyer’s Guide

If you want to buy window locks for your home, you might be wondering about the kind of factors to take into consideration. Let’s have a look at some of the most important ones now.

  • Style

There are several different styles of window lock, each with its own advantages and disadvantages.

Sliding window locks can be clipped into the frame of a window to prevent the window sliding open any further than the lock.

These are useful if you want to lock a window completely closed – but you can also use them to leave enough of a gap for ventilation while preventing intruders from entering or young kids from falling out.

With this type, there are two options. Some can be opened with regular hex keys. These are perhaps safer if you need to escape in a hurry.

However, if you want to prevent kids from opening them, you might choose ones that only accept a unique key that comes with them.

Another option is a bar lock. With these, a bar is placed in the window to prevent it from sliding open. They are even more solid than sliding window locks and are harder to break.

Alternatively, you could choose a sash lock. These are like sliding window locks but allow you to open and close the lock without the need to use a key or hex key.

  • Vertical or horizontal windows

When choosing a lock, you should make sure it is compatible with your type of window. For example, some are designed for use with both horizontal- and vertically-sliding windows while others work with horizontal sliders only.

  • Tough and durable

You should make sure that any lock you choose is tough and durable. It makes no sense to attach a weak lock that a burglar could easily break when trying to gain access to your home.

  • Ease of installation

When choosing, you should also pay attention to how easy it is to install a lock. Does it need special tools? Will you have to drill holes in your window frame?

Some locks can be attached quickly and easily without the need to use any tools – these are often the simplest solutions for adding extra security to your home.

  • Aesthetics

Although a window lock is primarily a functional item, some people might not be happy about installing something ugly on their windows.

In that case, don’t forget to pay attention to how the locks you choose look – there’s nothing wrong with picking something that looks attractive as long as it does its job properly.

Many solid options to choose from

As you can see, there are lots of options to choose from, and many of them are extremely affordable. If you are on the lookout for a locking system for your home but are unsure which one to go for, any of the options in our review would be a great place to start your search.

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