Peek: preview a file with Ctrl+Space, no app required

Mac users have the Space bar: select a file, press it, and see the contents. On Windows, the same thing has traditionally meant opening the whole app — and waiting for it to launch. Microsoft's free PowerToys fill that gap with the Peek module: select a file in File Explorer, press Ctrl+Space, and a lightweight window instantly shows what's in it. Arrow keys then flip through the other files in the folder without opening anything.

How to do it

1. Install PowerToys (Microsoft's free toolkit, available in the Microsoft Store) and confirm in the settings that the Peek module is turned on.
2. In File Explorer, select a file and press Ctrl + Space — a preview window opens: images, text files, code, web pages, and a range of other formats.
3. The left and right arrow keys step through previews of the other files in the folder — ideal for quickly scanning a whole batch.
4. A button in the preview lets you open the file directly in its default app once you've confirmed it's the right one. Close with Esc.
5. If the shortcut clashes with another app, you can change it in the PowerToys settings.

A typical scenario

You're hunting for one specific version of a contract among twelve files named “contract_final,” “contract_final2,” and “contract_final_REALLY.” Without a preview, that means opening Word twelve times, waiting, closing. With Peek, you select the first file, press Ctrl+Space, and arrow through all of them in a few seconds — you spot the right one by eye and open it directly.

It works just as well on a folder of phone photos, a batch of downloaded PDFs, or checking what's actually in a file a colleague sent with a meaningless name.

What you get out of it

• Time: launching a heavy app for a three-second glance is one of the most expensive operations in an office day — and you do it many times a day.
• Faster decisions: delete, rename, forward? You decide based on the content, not the filename.
• Fewer open windows: searching doesn't leave your desktop buried under six app windows you never actually needed.
• Safer handling of unfamiliar files: you can check the contents of an attachment or a downloaded file without launching it in a full app — a saner first step for anything suspicious.

Pro tip

File Explorer also has a built-in option: the preview pane, toggled with Alt + P, keeps a preview of the selected file permanently visible on the right side of the window. It's handy when you're sorting files for a longer stretch; Peek, by contrast, is better for a quick one-off glance. The two complement each other nicely — and on a Mac, Quick Look via the Space bar does the same job.