CRM on Next.js 16 (App Router) + Postgres (Neon) + Better Auth

✓ Verified 2026-06-21 · next 16.2.9 · postgres 3.4.9 · better-auth 1.6.20

Type-checked against the real SDKs, migration applied to a live Postgres, pooling tested — then tracked for upstream drift and re-verified when it moves. How we verify →

What you're getting

Setup

bun add next react react-dom drizzle-orm postgres better-auth

Environment variables:

Apply the schema: bunx drizzle-kit push

Initialization

src/lib/db.ts — Database client

import { drizzle } from "drizzle-orm/postgres-js";
import postgres from "postgres";

// Neon pooled endpoint = PgBouncer transaction mode → prepared statements off.
// ponytail: single module-level client; the serverless runtime + PgBouncer do
// the pooling, so no custom pool/globalThis singleton dance needed.
const client = postgres(process.env.DATABASE_URL!, { prepare: false });

export const db = drizzle({ client });

src/lib/auth.ts — Auth instance

// Better Auth instance (self-hosted, Next.js 16 (App Router)).
import { betterAuth } from "better-auth";
import { drizzleAdapter } from "better-auth/adapters/drizzle";
// Reuse the SAME postgres-js/Drizzle client the db slice exported in
// src/lib/db.ts — Better Auth shares the pooled `DATABASE_URL` connection.
import { db } from "./db";

export const auth = betterAuth({
  // Drizzle adapter over the shared client; provider "pg" => Postgres DDL
  // for Better Auth's own user/session/account/verification tables.
  database: drizzleAdapter(db, { provider: "pg" }),
  // ponytail: email+password is the shortest real auth that works out of
  // the box — add socialProviders / plugins here when the app needs them.
  emailAndPassword: { enabled: true },
  secret: process.env.BETTER_AUTH_SECRET,
  baseURL: process.env.BETTER_AUTH_URL,
});

export type Session = typeof auth.$Infer.Session;

app/api/auth/[...all]/route.ts — Route handler

// Mount Better Auth on Next's route layer.
import { toNextJsHandler } from "better-auth/next-js";
import { auth } from "@/lib/auth";

export const { GET, POST } = toNextJsHandler(auth);

proxy.ts — Route protection

// Session-protection proxy for Next.js 16 (App Router) (Next 16 renamed middleware.ts → proxy.ts).
// ponytail: getSessionCookie only checks the cookie EXISTS (no DB hit at
// the Edge runtime) — do the real auth.api.getSession() check inside
// protected Server Components / route handlers. This just bounces
// logged-out users before render.
import { NextResponse, type NextRequest } from "next/server";
import { getSessionCookie } from "better-auth/cookies";

export function proxy(request: NextRequest) {
  const sessionCookie = getSessionCookie(request);
  if (!sessionCookie) {
    return NextResponse.redirect(new URL("/sign-in", request.url));
  }
  return NextResponse.next();
}

export const config = {
  // ponytail: guard the SaaS app surface; widen the matcher per app-type.
  matcher: ["/dashboard/:path*", "/settings/:path*"],
};

Sales CRM schema: companies, contacts, pipelines, deals & activities

import { relations, sql } from "drizzle-orm";
import {
  bigint,
  check,
  index,
  pgTable,
  text,
  timestamp,
  uuid,
} from "drizzle-orm/pg-core";
// Better Auth owns identity; we only reference its `user` table by id.
import { user } from "./auth-schema";

export type DealStage = "lead" | "qualified" | "won" | "lost";
export type ActivityType = "call" | "email" | "note";

/** Account record: the organization a set of contacts belongs to. */
export const companies = pgTable(
  "companies",
  {
    id: uuid("id").primaryKey().defaultRandom(),
    name: text("name").notNull(),
    // Primary web domain — opaque key we de-dupe accounts on.
    domain: text("domain"),
    createdAt: timestamp("created_at", { withTimezone: true })
      .notNull()
      .defaultNow(),
  },
  (t) => [index("idx_company_domain").on(t.domain)],
);

/** A person we sell to. Company is nullable (a lead can exist before we know
 *  their employer); owner is the Better Auth user accountable for the contact. */
export const contacts = pgTable(
  "contacts",
  {
    id: uuid("id").primaryKey().defaultRandom(),
    // Nullable: unattached leads get a company once qualified.
    companyId: uuid("company_id").references(() => companies.id, {
      onDelete: "set null",
    }),
    email: text("email").notNull(),
    name: text("name"),
    // Better Auth's user.id is text — match it, don't recast.
    ownerId: text("owner_id")
      .notNull()
      .references(() => user.id, { onDelete: "cascade" }),
    createdAt: timestamp("created_at", { withTimezone: true })
      .notNull()
      .defaultNow(),
  },
  (t) => [
    index("idx_contact_company").on(t.companyId),
    index("idx_contact_owner").on(t.ownerId),
  ],
);

/** Named sales pipeline deals move through (e.g. Inbound, Enterprise). */
export const pipelines = pgTable("pipelines", {
  id: uuid("id").primaryKey().defaultRandom(),
  name: text("name").notNull(),
  createdAt: timestamp("created_at", { withTimezone: true })
    .notNull()
    .defaultNow(),
});

/** An open/closed opportunity against a contact, in a pipeline, owned by a
 *  Better Auth user. amount in integer cents (no float money). */
export const deals = pgTable(
  "deals",
  {
    id: uuid("id").primaryKey().defaultRandom(),
    contactId: uuid("contact_id")
      .notNull()
      .references(() => contacts.id, { onDelete: "cascade" }),
    pipelineId: uuid("pipeline_id")
      .notNull()
      .references(() => pipelines.id),
    ownerId: text("owner_id")
      .notNull()
      .references(() => user.id, { onDelete: "cascade" }),
    title: text("title").notNull(),
    // ponytail: money as integer cents — no float, no numeric type churn.
    amountCents: bigint("amount_cents", { mode: "number" })
      .notNull()
      .default(0),
    stage: text("stage").$type<DealStage>().notNull().default("lead"),
    closeDate: timestamp("close_date", { withTimezone: true }),
    createdAt: timestamp("created_at", { withTimezone: true })
      .notNull()
      .defaultNow(),
  },
  (t) => [
    // Drives the pipeline board "deals grouped by stage" query.
    index("idx_deal_stage").on(t.stage),
    index("idx_deal_contact").on(t.contactId),
    check(
      "deals_stage_check",
      sql`${t.stage} in ('lead','qualified','won','lost')`,
    ),
  ],
);

/** Append-only interaction trail against a deal, logged by a Better Auth user. */
export const activities = pgTable(
  "activities",
  {
    id: uuid("id").primaryKey().defaultRandom(),
    dealId: uuid("deal_id")
      .notNull()
      .references(() => deals.id, { onDelete: "cascade" }),
    // Who logged the interaction.
    actorId: text("actor_id")
      .notNull()
      .references(() => user.id, { onDelete: "cascade" }),
    type: text("type").$type<ActivityType>().notNull().default("note"),
    body: text("body"),
    occurredAt: timestamp("occurred_at", { withTimezone: true })
      .notNull()
      .defaultNow(),
  },
  (t) => [
    // Drives the per-deal timeline (most-recent-first).
    index("idx_activity_deal_time").on(t.dealId, t.occurredAt),
    check(
      "activities_type_check",
      sql`${t.type} in ('call','email','note')`,
    ),
  ],
);

export const companiesRelations = relations(companies, ({ many }) => ({
  contacts: many(contacts),
}));

export const contactsRelations = relations(contacts, ({ one, many }) => ({
  company: one(companies, {
    fields: [contacts.companyId],
    references: [companies.id],
  }),
  owner: one(user, { fields: [contacts.ownerId], references: [user.id] }),
  deals: many(deals),
}));

export const pipelinesRelations = relations(pipelines, ({ many }) => ({
  deals: many(deals),
}));

export const dealsRelations = relations(deals, ({ one, many }) => ({
  contact: one(contacts, {
    fields: [deals.contactId],
    references: [contacts.id],
  }),
  pipeline: one(pipelines, {
    fields: [deals.pipelineId],
    references: [pipelines.id],
  }),
  owner: one(user, { fields: [deals.ownerId], references: [user.id] }),
  activities: many(activities),
}));

export const activitiesRelations = relations(activities, ({ one }) => ({
  deal: one(deals, { fields: [activities.dealId], references: [deals.id] }),
  actor: one(user, { fields: [activities.actorId], references: [user.id] }),
}));

Connection & security

## Next.js 16 ↔ Postgres pooling (Neon pooled endpoint, PgBouncer transaction mode)

Connect through Neon's **pooled** endpoint (`-pooler` host) via `DATABASE_URL`. Serverless
functions are short-lived and concurrent, so PgBouncer in **transaction mode** is what keeps
Postgres' connection ceiling from being blown.

### `prepare: false` is mandatory
Transaction-mode PgBouncer hands each transaction a different backend, so server-side prepared
statements (postgres-js' default) silently break across the pool. Disable them on the client:
`postgres(url, { prepare: false })`. This is also why **Drizzle, not Prisma**, is paired here —
Prisma's prepared-statement reliance is a blocked intersection on this endpoint.

### Connection reuse
- Construct the postgres-js client at **module scope** (`src/lib/db.ts`) so warm function
  instances reuse one socket instead of opening one per request.
- Cap the driver pool small — `max: 1` per instance. The shared pool lives in PgBouncer, not in
  your function; a large per-instance `max` just multiplies idle connections across instances.
- Keep `idle_timeout` ~20s and `connect_timeout` ~10s so frozen instances release backends fast.

### No session-level features
Transaction mode forbids anything that spans transactions on one backend: `LISTEN/NOTIFY`,
session-scoped `SET`, advisory-lock sessions, server-side cursors, and `WITH HOLD`. Need any of
those? Use Neon's **direct** (non-pooled) endpoint for that path only.

### Thresholds
- Drizzle/postgres-js: `prepare: false`, `max: 1`, `idle_timeout: 20`, `connect_timeout: 10`.
- Neon Free pooled budget is ~10k client connections; keep concurrency well under the project's
  `max_connections` (often 100–900 by plan) by leaning on PgBouncer, never on driver pooling.

Decisions & compatibility

Related stacks