How to Use Vercel Preview Deployments for Team Code Reviews
Every branch you push to a Vercel project gets its own live URL. Teams that use this well review real, clickable changes instead of reading diffs — and catch environment bugs before merge.
What Is a Preview Deployment?
Vercel builds three environments: production (your domain), preview (every non-production branch), and development (local). A preview deploy is a full build with its own URL, so a reviewer can click through the change without running anything locally.
How Do You Turn On Previews?
They’re on by default once your repo is connected. Push a branch, open a pull request, and Vercel comments the preview link on the PR automatically. No configuration step exists to enable it — only settings that change behavior.
- Push a feature branch to your connected repo.
- Wait for the Vercel check to finish (usually under two minutes).
- Open the preview URL from the PR comment.
- Test the change; leave review comments tied to the live version.
How Do Preview Environment Variables Work?
Vercel lets you scope variables per environment. A preview build can point at a staging database while production points at the live one — the same code, different config. Set this in Project Settings → Environment Variables and choose which environments each variable applies to.
| Environment | Trigger | Typical data source |
|---|---|---|
| Production | Main branch | Live database |
| Preview | Any other branch | Staging database |
| Development | Local machine | Local/dev database |
How Do You Keep Previews Private?
Preview URLs are public by default, which is a problem for unreleased features. Vercel’s password protection and Vercel Authentication (available on paid plans) gate previews behind a login. For sensitive projects, enable protection before inviting outside reviewers.
Where Do Previews Get Messy?
Cost creeps up when dozens of branches deploy at once on metered plans, and stale preview environments can accumulate if you never clean up. Preview builds also consume build minutes, so a repo with frequent tiny commits can burn through your quota. Squash and deploy deliberately.
Quick Summary
- Vercel creates a preview URL for every non-production branch automatically.
- Preview variables can point at a staging database, separate from production.
- Preview URLs are public unless you enable password protection.
- Build minutes and bandwidth are consumed by each preview.
- Great for review workflows; prune stale branches to control cost.
