Sharing links are convenient because anyone with the link can open the file. That's also the weakness. Links get forwarded, pasted into the wrong chat, saved in browser history or caught by email scanners.

For most files that's fine. For tax documents, ID scans, contracts or anything with personal data, it's worth adding a lock that doesn't depend on the link staying private. That lock is encryption with a password.

The easy, free method: 7-Zip

7-Zip is free and open source. On Windows it's the simplest way to make an encrypted archive.

Install 7-Zip from its official site, 7-zip.org.
Right-click the file or folder → 7-Zip → Add to archive...
Set Archive format to 7z.
Under Encryption, type a password twice.
Make sure the method is AES-256.
Tick Encrypt file names.
Click OK.

You now have a .7z file that's useless without the password. With "Encrypt file names" on, someone without the password can't even see what files are inside.

On a Mac

Keka is a free archiver for macOS that can create password-protected 7z files. Drag files onto it, pick 7z, set a password, done.

You may see advice to use the terminal command zip -e. It works, but it uses the old ZipCrypto method, which is considered weak. Fine for keeping casual eyes out, not for anything that matters.

What about the recipient?

This is where you need to think about who's on the other end.

Windows 11 (recent versions): can open 7z files natively, though encrypted ones may still be smoother with 7-Zip installed.
Mac: needs Keka or The Unarchiver (both free).
Phones: iPhone's Files app handles ZIP but not 7z. There are free apps for this, but it's an extra step.

If you're sending to someone who isn't comfortable installing software, a ZIP with AES-256 encryption is a reasonable middle ground. 7-Zip can create it: choose "zip" as the format and AES-256 as the method. Be aware that the built-in Windows extractor may fail to open AES-encrypted ZIPs, so they might still need 7-Zip or a similar tool.

PDFs have their own password option

For a single document, a password-protected PDF is often the most recipient-friendly option, because every PDF reader knows how to ask for the password.

Microsoft Word: File → Save As → PDF, then Options → Encrypt the document with a password.
Mac Preview: File → Export as PDF, then show details and set encryption with a password.
Adobe Acrobat: Tools → Protect → Encrypt with Password.

Sending the password: the part people get wrong

If you send the file and the password in the same email, you haven't added much protection. Anyone who gets that email has both.

Send the password through a different channel:

File link by email, password by text message.
File link in a chat app, password in a phone call.
Or agree on the password in person ahead of time.

It's a small inconvenience, and it's what makes the encryption actually matter.

Choosing a password

Encryption is only as good as the password. AES-256 is effectively unbreakable, but "1234" is not. For files you're sending, use something long and random, or a few random words strung together, such as "harbor-velvet-cactus-ninety". Length beats complexity.

Don't reuse a password you use for an account. If you send it over text, assume it might be seen by someone else eventually.

Encryption plus expiring links

These two approaches complement each other. An expiring link limits how long the file is reachable. Encryption limits who can read it even if the link leaks. For sensitive files, using both is a sensible default.

When encryption is overkill

Don't let this put you off sharing ordinary files. Holiday photos, a draft presentation or a playlist don't need a password. Save the extra step for things you'd be uncomfortable seeing posted publicly: personal identification, financial records, medical information, private business data.

Recap

7-Zip (Windows) or Keka (Mac), 7z format, AES-256, encrypt file names.
For single documents, a password-protected PDF is easiest for recipients.
Send the password separately.
Use a long password you don't use anywhere else.

How to Password-Protect a File Before You Send It