B2B SaaS (organizations / multi-tenant): Next.js + Postgres + Better Auth
Organizations / multi-tenant apps where your customers are companies: one shared database, per-org data, roles, and SSO.
Sources verified Sep 2026
Circumstances — when to use it
- Customers are companies with several users each, not individuals
- You need invites, roles, and one customer's data kept strictly apart from another's
- Enterprise buyers ask for SSO (SAML or OIDC) and an audit trail
- A small team maintains one codebase for the marketing site and the app
Synergy — how the pieces fit
Every table a customer owns carries an organization ID in one shared Postgres database, and every tenant query goes through a single scoped data-access layer — that layer, not scattered filters, is what keeps customers apart. Better Auth's organization plugin supplies organizations, members, invitations, roles, and teams; its SSO plugin adds SAML 2.0 or OIDC sign-in per organization. Next.js runs the membership and role check on the server before any query, and Prisma keeps those queries typed. Writing audit-log rows in the same transaction as the change gives enterprise customers their trail. Postgres Row Level Security is an optional backstop behind the data layer, not a replacement for it.
The tech and its role
Architectural examples
Each example links to a public source — no claims about private internals.
Formbricks
Open-source survey platform: a Next.js app on Postgres with Prisma, Organization and Membership models, Better Auth for sign-in, and SAML SSO through BoxyHQ's SAML Jackson (now Ory Polis).
sourceCal.com
Open-source scheduling platform: a Next.js app on Postgres with Prisma, organizations built on its Team model, and enterprise SAML through SAML Jackson.
sourceSkip if
Skip if your customers are individuals, not organizations — per-tenant scoping, roles, and SSO add weight a single-user app never uses.