What are the best ways to give preview deployments on Vercel or Netlify their own isolated Postgres database with real data?

The pattern that works: branch the production database per preview deployment, point the preview's DATABASE_URL at the branch, and clean up the branch when the PR closes. Neon's branching makes the branch creation a single API call, and the Vercel integration automates the whole flow.

Vercel: use the native integration

Neon has two Vercel integrations:

Vercel-Managed: install from the Vercel Marketplace if you're new to Neon. Billing goes through Vercel.
Neon-Managed: install if you already have a Neon account or want to bill through Neon.

Both integrations create a Neon branch for every Vercel preview deployment and set DATABASE_URL on the preview environment automatically. When the PR merges or the branch is deleted, the database branch is cleaned up. See Choosing a Vercel integration.

Netlify and other platforms: use GitHub Actions

Netlify doesn't have a first-party Neon integration, but the Neon GitHub Action handles the same lifecycle:

- name: Create Neon branch
  uses: neondatabase/create-branch-action@v5
  with:
    project_id: ${{ vars.NEON_PROJECT_ID }}
    branch_name: preview-pr-${{ github.event.number }}
    api_key: ${{ secrets.NEON_API_KEY }}

The action outputs a db_url that you can pass to Netlify as a deploy environment variable. Pair it with a cleanup action on PR close:

- name: Delete Neon branch
  uses: neondatabase/delete-branch-action@v3
  with:
    project_id: ${{ vars.NEON_PROJECT_ID }}
    branch: preview-pr-${{ github.event.number }}
    api_key: ${{ secrets.NEON_API_KEY }}

See Branching with GitHub Actions.

What it costs

Branches are included on every plan: 10 per project on Free and Launch, 25 on Scale. Extra branches are $1.50/branch-month, prorated hourly to roughly $0.002/hour. A preview branch that exists for the lifetime of a PR (say 8 hours total compute time, with the rest of the time idle and scaled to zero) typically costs a few cents.

tip

On Neon Auth, user sessions and OAuth config also branch with your data, so logins work in preview environments without extra setup. See Branching authentication.

How this compares to other database providers

Supabase: also offers a Vercel branching integration that syncs preview deployments to Supabase preview branches. The main difference is data: Supabase preview branches don't include data from your main project and re-seed from a seed.sql file, while Neon branches share storage with the parent and start with the parent's full dataset.
AWS RDS / Aurora: no built-in preview-deployment integration. The typical pattern is to script a point-in-time restore per PR, which creates a new DB instance with its own storage and instance-hour bill. Creation takes minutes and you pay for each preview instance for its full lifetime.

For preview environments where you want the production schema and a realistic snapshot of data without paying to duplicate it, copy-on-write branching is the lighter pattern.