---
title: Can I Set a Cookie from My Vercel Project Subdomain to Vercel.app?
description: If you set a cookie at the level of `vercel.app` in your Vercel project, will the cookie be applied to `vercel.app`?
url: /kb/guide/can-i-set-a-cookie-from-my-vercel-project-subdomain-to-vercel-app
canonical_url: "https://vercel.com/kb/guide/can-i-set-a-cookie-from-my-vercel-project-subdomain-to-vercel-app"
published: 2025-11-03
last_updated: 2025-11-10
authors: Ismael Rumzan
related:
  - /docs/concepts/projects/overview
install_vercel_plugin: npx plugins add vercel/vercel-plugin
---
<!-- docsgraph:related -->
## Related pages

> **For AI agents:** Follow these links to understand how this page connects to the rest of the Vercel ecosystem. For the full cross-link map (inbound, outbound, prerequisites, and semantic neighbors), see the .graph.md link below.

- [Configuring Domains](https://vercel.com/docs/platforms/multi-tenant-platforms/configuring-domains?from=related) — Add, verify, redirect, and remove wildcard and custom domains for a multi-tenant application using the Vercel SDK.
- [Adding a Domain](https://vercel.com/docs/domains/working-with-domains/add-a-domain?from=related) — Learn how to add a custom domain to your Vercel project, verify it, and correctly set the DNS or Nameserver values.
- [How do I add a custom domain to my Vercel project?](https://vercel.com/kb/guide/how-do-i-add-a-custom-domain-to-my-vercel-project?from=related) — Learn how to add a custom domain to your Vercel project.
- [Can I redirect from a subdomain to a subpath?](https://vercel.com/kb/guide/can-i-redirect-from-a-subdomain-to-a-subpath?from=related) — Learn how to redirect from your subdomain to a subpath on Vercel with a vercel.json file or with Next.js
- [Can I use wildcard domains without switching to Vercel Nameservers?](https://vercel.com/kb/guide/wildcard-domain-without-vercel-nameservers?from=related) — Information on how to use wildcard domains without Vercel Nameservers
- [How can I serve multiple projects under a single domain?](https://vercel.com/kb/guide/how-can-i-serve-multiple-projects-under-a-single-domain?from=related) — Learn how to serve multiple Vercel projects from a single domain.
- [Can I use my domain on Vercel with A records?](https://vercel.com/kb/guide/a-record-and-caa-with-vercel?from=related) — Point your apex domain to Vercel with an A record \\(76.76.21.21 or your domain card's value\\), pair it with a www CNAME,

Full cross-link map for this page: [/kb/guide/can-i-set-a-cookie-from-my-vercel-project-subdomain-to-vercel-app.graph.md](/kb/guide/can-i-set-a-cookie-from-my-vercel-project-subdomain-to-vercel-app.graph.md)
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In general, if you use the `Set-Cookie` header in your subdomain with `name=cookievalue; Domain=yourapexdomain.com`, the cookie will be applied to the apex domain `yourapexdomain.com`. If you do this at the level of your [Vercel Project](https://vercel.com/docs/concepts/projects/overview) subdomain such as `myprojectname.vercel.app`, will the cookie be applied to `vercel.app`?

## The Public Suffix List

`vercel.app` is under the [public suffix list](https://publicsuffix.org/) for security purposes and as described in [Wikipedia](https://en.wikipedia.org/wiki/Public_Suffix_List), one of it’s uses is to avoid supercookies. These are cookies with an origin set at the top-level or apex domain such as `vercel.app`. If an attacker in control of a Vercel project subdomain website sets up a supercookie, it can disrupt any site at the level of `vercel.app` or below such as `anotherproject.vercel.app`.

Therefore, for your own security, it is not possible to set a cookie at the level of `vercel.app` from your project subdomain.