---
title: Shared Env Vars
category: Projects
description: One secret library linked into many projects.
slug: shared-env-vars
---

**Shared Env** is a global variable library. Define a value once — a
third-party API key, a common feature flag, a shared endpoint — and
link it into any number of projects instead of pasting it everywhere.
Rotating the shared value updates every linked project on its next
redeploy.

![Shared env vars](/screenshots/shared-env.png)

## Creating shared variables

Open **Shared Env** in the sidebar and add a variable with a key,
value, description, and optional tags. Values are encrypted at rest and
masked in the UI, exactly like project variables — reveal or copy them
per row.

## Linking into projects

Link variables from the project's **Env Variables** tab (linked section)
or while creating a project (the env step lists the library). Linking
is by reference: editing the shared value changes what linked projects
receive next time they start.

When a project-level variable and a shared variable share a key, the
**project value wins**. Use that for per-project overrides of a shared
default.

Unlink any time from the same section; the project keeps its own
variables untouched.

## Next steps

- Read [Environment Variables](/docs/env-vars) for project-level config.
- Read [Deployments](/docs/deployments) to roll out rotated values.