Is my v0 app secure? A pre-launch security checklist for v0 apps

Last updated October 25, 2026 · By Ember, SniffPup

Short answer: not automatically, but v0 starts you off with better guardrails than most. It checks generated code for security problems, warns about secrets in NEXT_PUBLIC_ variables and can move risky code to the server. Those checks look at your code. Once your app is live, every visitor can also read what it sends to the browser, so check that from the outside too.

SniffPup looks at your site the way a stranger would: secret keys in your HTML and same-origin JavaScript (masked in the report), public /.env and /.git files, a downloadable source map, missing security headers, cookie flags and HTTPS. It gives your site a 0–100 score. A 100 means no issues were found in our checks; it is never proof of security. Every critical issue comes with its full fix and a fix prompt you can paste into v0, free (with no critical, one other fix is free). It's passive: no logins, no attack traffic, and it never uses a secret key it finds. Signed in, your reports stay in the My scans tab so you can re-check after each publish. Then work through the steps below for the things no outside scan can see.

1. Know what v0 already checks

v0 is open about its guardrails, and they're worth knowing (v0 security docs, Vercel blog):

• While it generates: generated code gets a security analysis, and v0 watches for secrets in client code, misused NEXT_PUBLIC_ variables, tokens written to logs, prompt injection from unsanitized input and unsafe defaults for auth, routing and database access.
• Before deploy: Vercel says security issues are flagged and need review before the deploy goes out. Per the same post, the most common issues it catches are exposed API keys, NEXT_PUBLIC_ misuse and unauthenticated API routes.
• On the server: environment variables are encrypted and stored on Vercel, and server code runs as isolated Functions.

Read every warning before you click past it. A warning you accept still ships, and v0 can only check code it sees: keys you paste in later or settings you change in the Vercel dashboard are on you.

2. Keep secrets out of NEXT_PUBLIC_ variables

• v0 apps are Next.js apps. Any environment variable whose name starts with NEXT_PUBLIC_ is copied into the JavaScript every visitor downloads, at build time. That's by design, so only public values belong there: a Supabase anon key, a Stripe publishable key, an analytics ID.
• Secret keys (OpenAI, Stripe sk_, a Supabase service_role or sb_secret_ key, database URLs) need a name without the prefix, and should only be read in Route Handlers, Server Actions or Server Components. Add them under Project menu → Settings → Environment Variables.
• Use different keys for development and production, as v0's own best practices suggest, so a key used in a preview never unlocks your live data.

Paste this into v0:

List every environment variable this project reads. For each NEXT_PUBLIC_ variable, tell me if its value is safe for anyone to see. Move every secret key, token or database URL to a variable without the NEXT_PUBLIC_ prefix, read it only in server code (Route Handlers or Server Actions), and make sure the browser never receives it. List what you changed.

If a secret key has already been in a NEXT_PUBLIC_ variable, a public repo or the browser, rotate it at the provider. See what to do after leaking an API key.

If your v0 project is connected to a public GitHub repo, the free repo scan in the Sniff & Fix tab checks it for committed keys and .env files and for server-only keys with a public prefix. v0 creates a private repo by default, so this only applies if you made it public.

3. Check who can see your chat

Your v0 chat holds your prompts and your app's code. Per v0's sharing docs, a chat can be Private (or Only people with access on a team), shared with Everyone at your team, open to Anyone with the link, or set to Anyone on the web, which may be indexed by search engines and shown in public galleries. Team chats follow the workspace default unless an Owner changes it. If you ever pasted a real key into a chat, keep that chat private and rotate the key anyway.

4. Lock down your database

v0 can add Supabase, Neon, Upstash or Vercel Blob in a click, and for SQL databases it can create and change tables for you (v0 database docs). That's fast, so check the rules before real users arrive:

• Supabase: your anon key is meant to be public, so Row Level Security has to be on for every table, with policies that tie each row to its owner. See the Supabase RLS checker guide, or paste a policy into the free RLS policy explainer (also in the Sniff & Fix tab).
• Neon or another server-only database: the connection string must never get a NEXT_PUBLIC_ name. Every query should run on the server and check who is asking.

5. Test Server Actions and API routes signed out

Unauthenticated API routes are one of the issues Vercel lists as most common. An outside scanner can't see whether your routes check who is asking, so try it yourself:

1. Open DevTools → Network while you use your app signed in, and note the API routes it calls.
2. Open those routes in a private window, signed out. You should get an error or nothing private, never other users' data.
3. Sign in as a second test user and try to load the first user's records by changing an ID in the URL. It should fail.

Server Actions count too: a function that runs on the server can still be called by anyone who can load the page, so each one should check the signed-in user before it reads or changes data.

6. Pick who can open your deployments

When you first publish, v0 asks you to choose the deployment's visibility and domain (v0 deployment docs). Vercel's Deployment Protection has a Standard Protection scope that protects every deployment except your production domains, and an All Deployments scope that protects production too. If the app is an internal tool or still in testing, keep production protected until it's ready.

7. Check what your live site exposes

• Public /.env or /.git/config files (you should get a 404 or your app's normal page, never file contents)
• A public JavaScript source map, which can hand out your original code
• Missing security headers (Content-Security-Policy, Strict-Transport-Security, X-Frame-Options, X-Content-Type-Options, Referrer-Policy)
• Cookies without Secure, HttpOnly or SameSite flags

How to check: add /.env and then /.git/config to the end of your live URL, and look at the response headers in DevTools → Network. A free SniffPup scan checks all of these at once. For headers on their own, try the security headers checker.

Where SniffPup fits

v0's checks see your code as it's written, which an outside scanner can't. SniffPup sees what your live site actually serves to the public, which is what a stranger sees first. See exactly what the scanner does.

What v0's checks see vs. what an outside scan sees

The two work best together: fix what v0 flags, publish, then check what the public sees.

FAQ

A clean report is not a guarantee of security, and a 100 score means no issues were found in our checks, not proof of security. Only scan sites you own.

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