Passkeys for SaaS: The Migration Plan
Passkeys are cryptographic credentials that replace passwords for authentication. Each passkey consists of a public key stored on the server and a private key stored on the user's device. Authentication proves possession of the private key using device biometrics or PIN, without transmitting the private key or any shared secret. Passkeys are phishing-resistant because they are bound to the origin (domain) they were created for and cannot be used on lookalike sites. They are part of the WebAuthn (FIDO2) standard.
Written by Yashveer Singh, founder of Yashveer Labs.
What you need to know
- Passkeys are phishing-resistant because they are bound to the specific domain they were created for. No password manager prompt to fall for, no lookalike domain attacks.
- Passkeys sync across devices within platform ecosystems (Apple, Google, Microsoft). Users who set up a passkey on an iPhone can use it on their iPad and Mac automatically.
- Migration should be additive, not a cutover. Add passkey support alongside passwords, prompt users to create passkeys after successful password authentication, and let adoption grow over time.
- Every passkey implementation needs an account recovery path for users who lose all their registered devices. Design this before launch, not after the first user gets locked out.
- WebAuthn is the underlying standard. Passkeys are the consumer-friendly name for platform-backed WebAuthn credentials. The technical implementation uses the WebAuthn API.
The core argument
Passkeys represent the most significant improvement in authentication security for typical SaaS users in a decade. Phishing is responsible for a significant portion of credential compromise incidents, and passkeys are technically immune to phishing when implemented correctly. For a SaaS product serving business users, migrating to passkey support is a competitive and security differentiator that gets easier to implement as platform support matures.
The migration challenge is not technical complexity (WebAuthn libraries handle the protocol correctly) but user experience design. Authentication is one of the highest-stakes user experiences in a SaaS product: a friction increase in the sign-in flow causes measurable drop-off, and a confusing passkey setup flow causes users to give up and stick with passwords. The migration plan must include a setup flow that is clear about what a passkey is, a prompt that appears at the right moment (after successful authentication, not on every sign-in), and a fallback that makes users who decline passkeys not feel penalized.
The most common failure mode I see in passkey implementations is not the WebAuthn protocol but the account recovery story. Passkeys are bound to devices. Users lose devices, sell devices, and switch platforms. An application that does not have a clear, tested account recovery flow will have users locked out of their accounts within weeks of launching passkeys. Recovery flows must be designed before launch: backup codes, backup email verification, administrator recovery, or a combination. The recovery flow must also not become the phishing vector that passkeys were meant to prevent (a recovery page that accepts only an email address is weaker than the password it replaces).
Common mistakes
- Implementing passkeys as a replacement for all authentication rather than as an addition. Users on older devices, users in enterprise environments with managed devices, and users who have not opted in to their platform's credential sync are not ready for passkey-only authentication. Add passkeys as an option; do not remove passwords immediately.
- Not handling the cross-device authentication scenario. Users frequently sign in on a device that does not have their passkeys (a work computer, a public terminal). WebAuthn supports cross-device authentication via QR code and Bluetooth, but this flow must be tested and documented. Users who cannot figure out how to authenticate from a new device will log a support ticket.
- Storing the credential ID insecurely. The public key credential is not sensitive (it is public key material), but the credential ID is a user identifier that should be treated with appropriate security. Store it encrypted at rest with the rest of user authentication data.
- Not prompting passkey creation at the right moment. Prompting immediately after a user creates a new account interrupts onboarding. Prompting before a user has experienced the product value produces low uptake. The highest conversion point for passkey creation prompts is immediately after a successful password authentication: the user is authenticated, the passkey benefit is obvious, and the setup takes 30 seconds.
- Not testing passkey authentication across browsers and platforms. WebAuthn behavior varies between Chrome, Safari, and Firefox, and between mobile and desktop. Test the registration and authentication ceremonies on at least four platform combinations (Chrome/Mac, Safari/iPhone, Chrome/Android, Edge/Windows) before launch.
Where to start
- Choose a WebAuthn library and read the server-side implementation guide. For Node.js, @simplewebauthn/server has the most comprehensive documentation. For providers like Clerk or Auth0, passkeys may be a configuration option. Understand the registration and authentication ceremonies before writing implementation code.
- Design the passkey registration UX before implementation. Decide: when does the passkey creation prompt appear, what does the explanation say, what happens when the user declines, and how does the user manage their registered passkeys. These design decisions are as important as the technical implementation.
- Design and test the account recovery flow. Before launching passkeys to any users, simulate the scenario where a user has no accessible passkeys and needs to recover their account. Document the steps, test the flow manually, and ensure it cannot be bypassed with social engineering.
Related reading
Frequently asked
The engineer behind this page
This was written by Yashveer Singh. Full stack developer, founder of Yashveer Labs, currently in Class 12 in New Delhi, shipping production systems while most of my peers are still writing their first console app. I am pointing the work, on purpose, at machine learning, AI engineering, and cybersecurity. If you are reading this because you want to hire someone who will not waste your time or your money, that is the role I am built for.
Posts that line up with this one.
- Security, Auth, and Compliance
OWASP Top Ten for SaaS in 2026
The OWASP Top Ten is the standard list of critical web application security risks. Here is what each risk means in practice for a SaaS product, which ones are still commonly exploited in 2026, and how to address each without over-engineering the fix.
- Security, Auth, and Compliance
PCI DSS for SaaS Touching Payments: Patterns to Avoid the Trap
PCI DSS compliance is required for any product that processes, transmits, or stores cardholder data. Here is how to reduce your compliance scope to the minimum and which architecture patterns avoid the most expensive compliance requirements.
- Security, Auth, and Compliance
Secrets Management for SaaS: Vault, AWS Secrets Manager, Doppler
Environment variables in .env files work until they do not. At scale, secrets management needs audit trails, rotation, and least-privilege access. Here is how Vault, AWS Secrets Manager, and Doppler compare and which to choose.
- Security, Auth, and Compliance
Server Side Request Forgery: The Quiet Killer in SaaS Integrations
SSRF lets attackers make your server request internal resources they cannot access themselves. SaaS products that fetch external URLs are especially vulnerable. Here is how it works and how to prevent it.