B2B IDENTITY LAYER · ARD-G05

Best Auth Solutions for B2B SaaS

In B2B SaaS the auth decision is made once and paid for forever: switching identity providers means migrating every tenant, every session and every SSO connection. The four viable paths split on one question — do you want to operate the auth surface yourself, or rent it? Renting costs money per monthly active user and per enterprise connection; operating it yourself costs engineering weeks you will not spend on product.

Audited：2026-10-22Reading：9 min

All four products vetted against their own pricing and documentation pages (2026-10). No independent load or security testing was performed — where a vendor publishes no figure, that is stated rather than estimated.

Clerk

Hosted Authentication with Prebuilt UIs
RECOMMENDED WINNER
Why It Wins

Ships sign-up, sign-in and user-profile UIs as components, and adds the access controls B2B onboarding actually needs — Invite-only mode, Waitlist mode, allowlist and blocklist, plus blocking sign-ups on disposable email addresses and email subaddresses.

Top Advantage: Enterprise features are itemised rather than bundled away: MFA and custom session lifetime from Pro, SSO and Directory Sync as per-connection add-ons, a SOC2 Report on Business, HIPAA available with a BAA on Enterprise, and a 99.99% uptime SLA on Enterprise.
Primary Limitation: Directory Sync connections are listed at $75/mo each from January 1, 2027, and satellite domains at $10/mo each. Removing Clerk branding and enabling MFA both require Pro, and Hobby pins session lifetime to a fixed 7 days.

Auth.js

Open-Source Auth Library You Self-Host
Why It Wins

Runs inside your own application, so no third-party service sits in the request path and every credential stays in your own database. For B2B teams with data-residency constraints, this is the only option with no external identity provider in the loop at all.

Top Advantage: Framework packages for Next.js, Qwik, SvelteKit and Express, with you supplying the auth.ts configuration and your own adapters. The entire auth surface — session shape, token contents, provider list — is yours to define.
Primary Limitation: You build and operate everything. MFA, SSO, account linking and session revocation are your code, and AUTH_SECRET is the one mandatory environment variable — generated via npx auth secret and kept secret by you.

Supabase Auth

Platform-Integrated JWT Auth with Row Level Security
Why It Wins

If you already run on Supabase, authentication and authorization arrive together: the Auth Token scopes database access row by row when combined with RLS policies, so per-tenant data isolation is expressed as database policy rather than application code.

Top Advantage: JWT-based auth with password, magic link, one-time password, social login and SSO, plus any OAuth2 or OIDC-compatible provider through Custom OAuth/OIDC Providers. Data requests made through the Supabase SDKs carry the Auth Token automatically.
Primary Limitation: Only makes sense inside the Supabase platform — there is no path to using it standalone. Billing is split across Monthly Active Users, Monthly Active Third-Party Users, Monthly Active SSO Users and Advanced MFA add-ons, so the true cost is spread over several meters.

WorkOS

Enterprise SSO, SCIM and Directory Sync
Why It Wins

AuthKit is free up to one million active users, which removes the auth line item entirely for an early-stage B2B SaaS — the opposite end of the spectrum from per-MAU billing.

Top Advantage: Enterprise SSO over SAML and OIDC is priced per connection with automatic volume discounts: $125 per connection at 1-15, dropping to $100 at 16-30, $80 at 31-50 and $65 at 51-100. Directory Sync covers provisioning, de-provisioning and role mapping. Annual Credits plans add a 99.99% uptime SLA.
Primary Limitation: Built for enterprise features rather than consumer auth — AuthKit itself is user management with social auth, MFA and RBAC, not a full self-serve signup product. Past one million users, AuthKit jumps to $2,500/mo per additional million.