How to Open a .key File on Windows or Mac

What a .key file is and which program opens it

A .key file is not one thing — the same extension covers several different file types, and which program opens it depends on what's actually inside. The most common .key files are Keynote presentations (Apple's version of PowerPoint), SSH private keys (used for secure server access), or license key files. Opening the wrong one in the wrong program will either show you gibberish or fail entirely.

Before you try to open it, look at where the file came from. Did someone email you a presentation? It's probably a Keynote file. Did a server administrator send it to you for remote access? It's an SSH key. Did you download it from software you just installed? It's likely a license file. The source tells you what you're dealing with.

Key Takeaways

.key files can be Keynote presentations, SSH private keys, or license files — the source of the file tells you which one you have.
Keynote files open in Apple Keynote on Mac, or in Microsoft PowerPoint or Google Slides on any computer if you convert them first.
SSH private keys should never be opened in a text editor on Windows or Mac — they are used by terminal commands and should stay protected.
License key files are text strings that you paste into software, not files you open — check the software's settings or preferences for where to paste it.
If you cannot identify what the .key file contains, opening it in a plain text editor (Notepad on Windows, TextEdit on Mac) will show you the first few lines without damaging anything.

Opening a Keynote presentation (.key file)

If the .key file is a Keynote presentation, the easiest route depends on what computer you have. On a Mac with Keynote installed, double-click the file and it opens automatically. If you do not have Keynote, or you are on Windows, you have two options: convert the file to PowerPoint format first, or open it in Google Slides through your web browser.

To convert a .key file to PowerPoint on a Mac, open Keynote, go to File > Open, select your .key file, then go to File > Export To > PowerPoint. Save the converted file with a .pptx extension. You can then open it in PowerPoint on Windows or Mac, or in Google Slides on any computer.

To open a .key file directly in Google Slides without converting it, go to Google Drive in your web browser, click the New button, select File Upload, and upload your .key file. Google Drive will convert it automatically and open it in Google Slides. You can then download it as a PowerPoint file if you need to keep a copy on your computer.

Understanding SSH private key files

If your .key file came from a server administrator or a cloud hosting service like AWS or DigitalOcean, it is almost certainly an SSH private key — a file that proves your identity when you connect to a remote server. Do not try to open this file in Keynote, PowerPoint, or any regular program. Do not email it to yourself or store it in a shared folder. SSH keys are security credentials, and treating them like regular documents puts your server at risk.

SSH keys are used from the command line (Terminal on Mac, Command Prompt or PowerShell on Windows). On Mac, you typically place the .key file in a hidden folder called .ssh in your home directory, then use a command like ssh -i ~/. ssh/your-key-file.key username@server-address to connect. On Windows 10 and later with OpenSSH installed, the process is similar. If you are not sure how to use the key, ask the person or service that gave it to you for connection instructions — they will tell you the exact command to run.

If you need to check what is in an SSH key file to verify it is the right one, you can open it in a plain text editor (Notepad on Windows, TextEdit on Mac) and look at the first line. It should say something like -----BEGIN RSA PRIVATE KEY----- or -----BEGIN OPENSSH PRIVATE KEY-----. If it does, you have the right file type. Close the file without saving any changes.

Handling license key files

Some software comes with a .key file that contains your license code — a long string of letters and numbers that proves you own the software. These files are not meant to be opened and read like a document. Instead, the software itself looks for the .key file in a specific folder, or you paste the key code into the software's settings or preferences.

Check the software's documentation or help section for where to place the .key file or where to enter the license code. Common locations are the software's installation folder, your user Documents folder, or a preferences window inside the program itself. If the software asks for a license key and you have a .key file, try opening the file in Notepad (Windows) or TextEdit (Mac) to see the code inside, then copy and paste that code into the software's license entry field.

Opening a .key file when you are not sure what it is

If you do not know where the file came from or what it contains, the safest first step is to open it in a plain text editor. On Windows, right-click the file, select Open With, and choose Notepad. On Mac, right-click the file, select Open With, and choose TextEdit. The file will open as plain text, and the first few lines will tell you what you are looking at.

If the file starts with text like -----BEGIN, it is an SSH key or certificate — close it without saving and do not try to open it in other programs. If it starts with readable text or XML code, it is a configuration or data file. If it looks like random characters or binary data, it may be encrypted or compressed. If the first line says something like KPF8 or contains Keynote-related text, it is a Keynote presentation that should be opened in Keynote or converted to PowerPoint.

Converting .key files to other formats

The only .key file format that needs regular conversion is Keynote presentations. As mentioned above, you can convert a .key file to PowerPoint (.pptx) by opening it in Keynote and using File > Export To > PowerPoint. You can also convert it through Google Slides by uploading the file and downloading it as PowerPoint.

SSH private keys and license key files should not be converted or moved between formats. If you have an SSH key in .key format and need it in a different format (like .pem), a server administrator can help you generate the right format. License keys are tied to the software that issued them and cannot be converted — if you need a different format, contact the software vendor.

Troubleshooting when a .key file will not open

If you double-click a .key file and nothing happens, the computer does not know which program to use. Right-click the file and select Open With (Windows) or Open With (Mac), then choose the program you want to use. If you think it is a Keynote file but Keynote is not listed, you may need to install Keynote first, or you can select PowerPoint or Google Slides instead.

If you try to open a .key file in Keynote and get an error message saying the file is not a valid presentation, it is not a Keynote file. Check the file's source again — it may be an SSH key, a license file, or a different file type altogether. If you are still stuck, open it in Notepad or TextEdit to see what the first few lines contain, and that will tell you what you actually have.

Frequently Asked Questions

Can I open a .key file on my phone or tablet?

Keynote presentations can be opened in the Keynote app on iPhone or iPad — just email the .key file to yourself and open it from the Mail app, or upload it to iCloud Drive and open it from Keynote. SSH private keys and license files should not be opened on a phone. If you need to use an SSH key from a phone, use a dedicated SSH app from your phone's app store, but this is uncommon for most users.

What if the .key file is password-protected?

Keynote presentations can be password-protected. If you try to open one and are asked for a password, enter the password the file's creator gave you. SSH private keys can also be password-protected — if you try to use one and are asked for a passphrase, use the passphrase the administrator provided. License key files are not password-protected.

Is it safe to email a .key file to myself?

Keynote files and license key files are safe to email. SSH private keys should never be emailed or sent over the internet — they are security credentials and should only be transferred through secure channels. If an administrator sent you an SSH key by email, ask them for a more secure method to receive it.

Why does my .key file have a different icon than other files?

The icon depends on what program your computer thinks should open the file. If it has a Keynote icon, your computer recognizes it as a presentation. If it has a generic document icon, the computer is not sure what it is. Right-click the file and select Properties (Windows) or Get Info (Mac) to see the file type listed, which will tell you what it actually is.

Can I rename a .key file to a different extension?

You can rename a Keynote .key file to .pptx if you have already converted it to PowerPoint format — but do not rename the file itself without converting it first, or it will not open. Do not rename SSH private keys or license files — the extension matters for how the system finds and uses them.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.