Solo 2

Solo 2 is an open-source FIDO2 security key for people who want phishing-resistant sign-in and locally stored passkeys. It suits everyday account protection as well as security work, with several USB and NFC configurations. Its strongest case is straightforward, touch-confirmed authentication; its key drawback is that a forgotten PIN can mean losing every passkey on the device.

Overview

Solo 2 supports FIDO2, WebAuthn, and U2F, letting it serve as a physical authentication factor for services that accept security keys. Basic use needs no software installation or drivers, so it can add protection without putting another app between users and their accounts.

A capacitive sensor with three contact points confirms sign-in when touched. The key works with services including Google, Microsoft, Facebook, Salesforce, GitHub, Dropbox, and Twitter/X. It can store about 100 credentials and passkeys on the device itself, without cloud backup. That favors users who want local control, but makes a backup key important: resetting after a forgotten PIN erases the stored passkeys.

Key features

• Touch confirmation: Physical contact is required to confirm authentication, adding an intentional step to sign-in.
• Local passkey storage: Credentials stay on the key rather than being copied to cloud services. Capacity of about 100 passkeys is ample for many personal accounts, but users must plan for recovery if the key is lost or reset.
• Open-source design: SoloKeys says the software is dual-licensed under Apache 2.0 and MIT, the hardware under CERN-OHL-S, and the documentation under CC-BY-SA 4.0. That is a meaningful fit for users who value inspectable designs and open licensing.
• Key management: The solo2-cli tool manages passkeys, firmware updates, PINs, PIV, and OpenPGP settings. Users comfortable with command-line tools have direct controls; the Solo 2 GUI is coming soon.
• Attestation: Standard Solo 2 devices ship with locked firmware and SoloKeys attestation certificates. The Hacker model omits attestation, a distinction relevant to buyers who need that assurance.

Pricing

Solo 2 is a one-time hardware purchase, with no free plan or trial. The least expensive option is the Solo 2C Security Key at $34, paid once-time purchase: USB-C, without NFC. It is the straightforward pick for users whose devices have USB-C and who do not need phone tap authentication.

• Solo 2 USB-A Security Key: $35, paid once-time purchase; USB-A, no NFC. Choose it for a USB-A port, accepting that it cannot authenticate by NFC.
• Solo 2 USB-A Hacker: $35, paid once-time purchase; USB-A, unlocked for custom firmware, no NFC. It targets developers, researchers, and makers who want firmware flexibility, not buyers seeking the standard attested model.
• Solo 2C+ NFC Security Key: $46, paid once-time purchase; USB-C with NFC.
• Solo 2A+ NFC Security Key: $46, paid once-time purchase; USB-A with NFC.

The NFC models cost more but add phone-friendly authentication; Solo 2+ supports NFC on compatible Android and iOS devices. Match the connector to the devices you use, and choose NFC if you expect to authenticate by tapping rather than plugging in. There is no subscription or recurring renewal described for these purchases.

Platforms

Solo 2 is listed for Android, iOS, Linux, macOS, web, and Windows. Its maker lists Chrome, Edge, Safari, Brave, and Firefox as supported browsers, and operating-system support also includes ChromeOS and xBSD. Solo 2+ NFC works with compatible Android and iOS devices; standard models without NFC do not offer that tap-based option.

Who it's for

Solo 2 suits individuals who want a physical key for supported online accounts, especially those who prefer open-source software and hardware and local passkey storage. Enterprise teams and security professionals are also among its intended users. The Hacker model is better aligned with developers, security researchers, and makers who specifically want unlocked custom firmware. Anyone who needs cloud-backed passkey recovery, or is unwilling to keep a backup key, should look elsewhere.

Pros and cons

• Pro: FIDO2, WebAuthn, and U2F support covers several established security-key standards, and basic setup does not require drivers or an installed app.
• Pro: Passkeys remain on the physical key, with capacity for about 100 credentials and no cloud copy.
• Pro: USB-A, USB-C, and NFC versions let buyers choose for their ports and compatible phones.
• Con: A forgotten PIN followed by a reset erases stored passkeys, so recovery depends on preparation such as registering a backup key.
• Con: The standard USB models lack NFC; buyers who need phone tap authentication must pay for a Solo 2+ version.
• Con: Managing advanced settings uses a command-line tool; the GUI is not yet available.

Alternatives

Security Keys is the broader category guide for comparing physical authentication keys.

• Yubico Authenticator is a free, open-source option for readers who already have a YubiKey and want to store credentials and generate codes with it; Solo 2 is a paid key with local passkey storage.
• YubiKey 5 Series is a paid alternative with USB-A and USB-C NFC models; consider it if that family better fits your connector needs.
• Deepnet SafeKey is another paid security-key option.
• FEITIAN ePass FIDO-NFC Security Key offers USB-A or USB-C, NFC, FIDO U2F/FIDO2, and HOTP/TOTP for $35, paid once-time purchase; pick it if those standards and code-generation support at that price match your needs.
• SafeNet MobilePASS+ is another paid authentication option.
• Token2 T2F2-NFC-Slim is a paid alternative with volume pricing beginning at two units.
• Nitrokey 3 is a paid, open-source hardware and software alternative, with the Nitrokey 3A Mini at €54, paid once-time purchase.
• Token2 PIN+ Release3.3 is a paid alternative with FIDO2.1/WebAuthn, U2F, PIV, OpenPGP, TOTP/HOTP, and capacity for up to 300 resident keys; consider it if those additional protocols and higher key capacity matter more than Solo 2's lower entry price.

Verdict

Solo 2 is a strong fit for users who want standards-based, touch-confirmed authentication, open-source design, and passkeys kept on a physical key. Its low-cost USB options make entry relatively direct, while NFC versions suit compatible phones. Choose another approach if you need cloud recovery or cannot keep a backup: a PIN reset erases stored passkeys, and that recovery trade-off is central to owning Solo 2.