---
title: Database Setup
description: Configure a database adapter for your self-hosted c15t backend.
---
The c15t backend requires a database to store consent records, subjects, audit logs, and policies. Five adapters are supported — choose the one that matches your existing stack.

## Adapters

### Kysely

```ts title="c15t.ts"
import { c15tInstance } from '@c15t/backend';
import { kyselyAdapter } from '@c15t/backend/db/adapters/kysely';
import { Kysely, PostgresDialect } from 'kysely';
import { Pool } from 'pg';

const db = new Kysely({
  dialect: new PostgresDialect({
    pool: new Pool({ connectionString: process.env.DATABASE_URL }),
  }),
});

export const c15t = c15tInstance({
  adapter: kyselyAdapter(db),
  trustedOrigins: ['https://example.com'],
});
```

### Drizzle

```ts title="c15t.ts"
import { c15tInstance } from '@c15t/backend';
import { drizzleAdapter } from '@c15t/backend/db/adapters/drizzle';
import { drizzle } from 'drizzle-orm/node-postgres';

const db = drizzle(process.env.DATABASE_URL);

export const c15t = c15tInstance({
  adapter: drizzleAdapter(db),
  trustedOrigins: ['https://example.com'],
});
```

### Prisma

```ts title="c15t.ts"
import { c15tInstance } from '@c15t/backend';
import { prismaAdapter } from '@c15t/backend/db/adapters/prisma';
import { PrismaClient } from '@prisma/client';

const prisma = new PrismaClient();

export const c15t = c15tInstance({
  adapter: prismaAdapter(prisma),
  trustedOrigins: ['https://example.com'],
});
```

### TypeORM

```ts title="c15t.ts"
import { c15tInstance } from '@c15t/backend';
import { typeormAdapter } from '@c15t/backend/db/adapters/typeorm';
import { DataSource } from 'typeorm';

const dataSource = new DataSource({
  type: 'postgres',
  url: process.env.DATABASE_URL,
});

export const c15t = c15tInstance({
  adapter: typeormAdapter(dataSource),
  trustedOrigins: ['https://example.com'],
});
```

### MongoDB

```ts title="c15t.ts"
import { c15tInstance } from '@c15t/backend';
import { mongoAdapter } from '@c15t/backend/db/adapters/mongo';
import { MongoClient } from 'mongodb';

const client = new MongoClient(process.env.MONGODB_URI);

export const c15t = c15tInstance({
  adapter: mongoAdapter(client),
  trustedOrigins: ['https://example.com'],
});
```

## Migrations

To create & update the database you can use the migrator which is included in the CLI:

| Package manager | Command              |
| :-------------- | :------------------- |
| npm             | `npx @c15t/cli`      |
| pnpm            | `pnpm dlx @c15t/cli` |
| yarn            | `yarn dlx @c15t/cli` |
| bun             | `bunx @c15t/cli`     |

## Table Prefix

If you share a database with other applications, use `tablePrefix` to namespace the c15t tables:

```ts
c15tInstance({
  adapter: kyselyAdapter(db),
  tablePrefix: 'c15t_',
  trustedOrigins: ['https://example.com'],
});
```

This prefixes all table names (e.g. `c15t_subject`, `c15t_consent`, `c15t_audit_log`).

## Schema Overview

The backend creates and manages these tables:

| Table             | Purpose                                                                            |
| ----------------- | ---------------------------------------------------------------------------------- |
| `subject`         | Consent subjects (users/devices). Tracks identification status and external IDs.   |
| `consent`         | Append-only consent records. Stores preferences, jurisdiction, IP, and timestamps. |
| `domain`          | Domain/website configuration for multi-domain setups.                              |
| `consent_policy`  | Versioned consent policies.                                                        |
| `consent_purpose` | Maps consent purposes to categories.                                               |
| `audit_log`       | Immutable log of all consent-related actions.                                      |