Understanding Where Next.js Fetch Cache is Stored and How It Differs Between Vercel Deployments and Self-Hosted Environments

[abhishekmardiya]

Summary

I have two separate deployments:

https://site-one.com/
https://site-two.com/

Both deployments are using the same codebase and both use the same tag (test), but each one calls a different API domain.

// site-one
const res = await fetch("https://api-site-one.com/get-data", {
  method: "GET",
  headers: {
    "Content-Type": "application/json",
  },
  cache: "force-cache",
  next: { tags: ["test"] },
});

// site-two
const res = await fetch("https://api-site-two.com/get-data", {
  method: "GET",
  headers: {
    "Content-Type": "application/json",
  },
  cache: "force-cache",
  next: { tags: ["test"] },
});

Does Next.js share this cached response globally across both deployments, or is each deployment isolated and maintains its own separate cache?

Additional Clarification:

Where exactly is this cache physically stored when deployed on Vercel vs when deployed on a self-hosted environment?

If there are any official docs explaining persistence, scope and isolation of fetch cache between deployments, please share — I couldn’t find a clear explanation.

Additional information

No response

Example

No response