The Thetis FIDO2 Fingerprint Key ($59.99) is something rare: a wallet-friendly biometric hardware security key. Though it lacks a USB-C version, the key can store your passkeys and your Time-based One-Time Password (TOTP) codes. We liked how easy it was to set up the key using a PIN, and we found its management app helpful. It's also the least-expensive biometric hardware security key we've reviewed. The big drawback? Fingerprint recognition. The device failed to record or recognize one of the testers' fingerprints in testing. Our Editors' Choice pick, the Yubico Security Key C NFC, is just $29 and offers the same authentication capabilities minus the biometrics.

Analyzing the Thetis FIDO2 Fingerprint Key

As expected for a fingerprint-reading key, setup goes beyond plugging the device into your computer's USB-C port and creating a PIN when prompted. That's the typical routine for non-biometric keys such the Yubico Security Key C NFC or Google's Titan Security Key. Instead, after connecting the Thetis FIDO2 Fingerprint Key to your computer, you'll need to navigate to the Thetis website to download management apps for macOS or Windows.

(Credit: Kim Key)

The Thetis FIDO2 Fingerprint Key supports the same authentication standards found in Yubico's Bio series keys: FIDO2, FIDO U2F, and WebAuthn. These are the most popular multi-factor authentication (MFA) methods, and they will be enough for most personal or business settings. If you are looking for a few more uses for a hardware security key and are willing to sacrifice biometrics, Yubico's 5 Series keys are designed for security professionals or other advanced users. For example, the $55 YubiKey 5C NFC can function as a smart card and supports the following authentication protocols: FIDO2, OATH–HOTP (Event), OATH–TOTP (Time), OpenPGP, Secure Static Passwords, Universal 2nd Factor (U2F), WebAuthn, and Yubico OTP.

Getting Started With the Thetis FIDO2 Fingerprint Key

The Thetis FIDO2 Fingerprint Key is enclosed in a hard plastic shield, which swings around to protect the USB-A connection and biometric sensor from scratches or dust when not in use. It's a neat feature, but it adds considerable bulk to the device. To compare, check out the Thetis key next to the diminutive YubiKey Bio.

(Credit: Kim Key)

That said, the key is still small enough to fit on a key ring, and there's a hole at the top of the device for that purpose.

One of the biggest barriers to entry for new users of privacy and security software is learning how to use the products. Thetis' website provides clear, step-by-step setup instructions detailing how to use the device to store passkeys and TOTP codes, or to employ it as an MFA method.

(Credit: Thetis/PCMag)

Trouble first came up during the setup process. After downloading the Thetis management app on a Windows desktop computer, I plugged in the key, designated a PIN, and tried to register my fingerprints. For reference, I am a woman with dark skin, tan finger pads, shallow finger grooves, and short nails. The key reader failed to recognize or store my prints. My partner has light skin, very light finger pads, prominent finger grooves, and short nails. I asked him to submit a fingerprint for testing, and the reader recorded his fingerprints without problems.

Biometrics is still a tricky science, and many factors can affect a biometric reader, including skin dryness. I moisturized my hands thoroughly and tried multiple fingers held at many angles, with varying degrees of pressure on the reader, but the FIDO2 failed to recognize my prints. In contrast, the YubiKey C Bio didn't have any trouble recognizing and recording my fingerprints in the same testing environment.

A biometric key that can't recognize fingerprints is, of course, not ideal and negatively affects the score. I used my partner's fingerprint to test the device for the rest of the testing period. You can also use the device using only a PIN code, but then you're paying for biometrics that you're not using.

Hands On With the Thetis FIDO2 Fingerprint Key

The Thetis FIDO2 Fingerprint Key works with macOS and Windows machines. The device doesn't have a USB-C option or other way to connect to mobile devices. We tested the key using a desktop computer running Windows 10.

(Credit: X/Google/PCMag)

First, we logged into a test account on X and added the Thetis FIDO2 Fingerprint Key to the account by visiting the Security and Privacy section. After following the on-screen prompts, my partner pressed the key's sensor when prompted to attach the key to the social media account. The next time we logged into the X account, it requested a touch confirmation via the security key to verify our identity, as expected. We were also able to create and store a passkey on the device for a Google account, and logged in using the fingerprint sensor.

(Credit: Thetis/PCMag)

The device's desktop app helps you register a PIN and fingerprints, but it doesn't organize your passkeys, which is not ideal. To do so, there's a somewhat clunky workaround for Google Chrome users involving disabling a Chrome setting using the Command Prompt (as described on the Thetis website), but it did not work for us in testing.

Verdict: The Thetis FIDO2 Fingerprint Key Isn't For Everyone

We were ready to love the Thetis FIDO2 Fingerprint Key; it's the least-expensive biometric key we've tried, and it supports today's most common authentication protocols. Thetis also provides thorough setup instructions and an easy-to-use desktop app. However, a biometric device that struggles to read fingerprints is not one we can recommend very easily. The YubiKey C Bio works on desktop and mobile devices, and it read our fingerprints with ease. And if you're looking for similar authentication options without biometrics, we recommend our Editors' Choice winner, the Yubico Security Key C NFC. It's an inexpensive security key with a sleek, slim form factor.