The Best Aftermarket Window Locks

Most windows come with standard locks, but if you need to baby-proof your home or beef up your security, a secondary window lock is a smart investment. We’ve compiled a list of the best window locks on the market to help you find the right ones for your home—starting with our favorite overall pick, the Windobully Window Lock.

You can slide the catch down to adjust the window opening. And the teeth inside the metal strip keep it from sliding back up—and keep your window from going up when it hits the catch. If you want to have your window fully open, just squeeze the sides of the catch to detach it from the metal strip.

We like that the Windobully lets you decide how wide you want your window to open every time you use it. But make sure it’s in the right spot before you mount it, because it’s difficult to remove once it’s stuck in place. We also found that the metal strip is susceptible to rusting from window condensation.

The bar also attaches to the inside of your window frame with a peel-and-stick hinge, so you can easily pivot it out of the way into a horizontal position (or vertical for horizontal sash windows) when you want to open the window completely.

The design of the Wedgit doesn’t allow for a ventilation option for double-hung vertical sash windows, but we like that you can use it to secure sliding doors. You’ll need some grip strength to twist the bar enough to release tension and move it out of the way, so it’s great for keeping young children safe.

You can’t use it to keep your windows locked shut unless you maximize the distance between the two attachment points (which might make it hard to lock and unlock,) so we recommend using it alongside a standard window lock. You’ll need a key to unlock and detach the cable, and you’ll need some skills with a screwdriver to complete this installation.

This fastening method helps you get maximum friction between the lock and the track so that the window won’t budge, even with applied force. It’s easy to remove—just flip the lever—but that means it might not be the best choice if you have curious little ones.

We like that this lock doesn’t leave unsightly marks on your windows and that you can move it to any position along the window track. Its sturdy diecast construction is another feature that sets it apart from similar window locks. But we’ve found that it may weaken if you frequently lock and unlock it to adjust its position.

To operate the Ashtonbee, you flip out a latch and lock it in place. The latch acts as a barrier, preventing the window from opening. To open the window fully, just release the lock, and the latch slides back down so it’s flush against the rest of the device (and won’t block the window from sliding open).

The Maxdot Adjustable Sliding Window Lock is another track lock device, but it secures to the track using a key. This makes it safer for homes with small kids, as long as you keep the keys out of reach. The key is designed like an Allen wrench, so you can turn it more for a tighter fit, and the bright yellow plastic key handle makes it easy to find, even in a junk drawer.

The Maxdot’s design makes it ideal for older, thicker framed windows, but it might leave a mark when it’s tightened. Like the Defender Sliding Window Lock, you can easily adjust the placement of your Maxdot on the window track to allow the window to be opened wider or be fully locked shut.

We like the unique design of the Andersen lock, because you can open your window without having to remove the lock, and it locks itself in place again automatically when you shut the window. This is one of the few locks on our list that requires screws, but it also meets the ASTM requirements for Window Fall Prevention Devices with Emergency Escape and (Egress) Release Mechanisms.

It’s made of metal and designed to work only for windows with wood frames. You can’t make any adjustments to the locking height once you’ve installed it, but you could install a second device to a different height to allow for a ventilation setting.

Different styles of windows open and close differently, so the style of lock you’ll need depends on the type of windows you have. Here are the four main types of moveable windows, along with the types of window locks that work best for them.

A sash window has one or two sashes that can slide up and down on tracks in a frame. Stop locks, bar locks, track locks, locking pins, and wedge stops all work for single-hung or double-hung windows.

A casement window is hinged on the side and opens outward with a turn crank. Locking pins are the best types of locks for casement windows.

An awning window opens outward with a hinge at the top of the window. Locking pins work well for awning windows.

Slider windows have one or two sashes that slide sideways on a track. Stop locks, bar locks, track locks, locking pins, and wedge stops are all suitable sliding window locks.

The Windobully Window Lock ticks a lot of boxes:

• Excellent adjustability
• Isn't easy for kids to remove
• Good for renters (take care not to peel paint)

It's our overall best choice for all sliding windows. 

We evaluated several types of window locks (such as track locks, wedge locks, and bar locks) to find those with the best construction, easiest installation, and affordable price tags. We also read user reviews to determine how the products perform in the real world. 

Learn more about our methodology.

• 5 Best Door Locks for Apartments and Renters
• Best Door Locks for Home Security
• Best Door and Window Sensors
• How to Tell if Your Locks Have Been Tampered With
• What to Do When You're Locked Out