Move from Vercel environment variables to Envlet

Keep one ENVLET_TOKEN in Vercel and let your functions pull the rest at boot.

About 15 minutes

01
Sign in once
Install the CLI and sign in. It shows a URL and a code; approve in the browser and you are in.
Terminal
```
npm install -g @envlet/cli
envlet login
```
02
Create a token per Vercel environment
Create a ci identity named vercel with one token per environment, so a preview deploy can never read production.
03
Set the one variable
Add ENVLET_TOKEN in Vercel for each environment, then remove the rest.
Terminal
```
vercel env add ENVLET_TOKEN production
vercel env add ENVLET_TOKEN preview
```
04
Inject at boot
For Next.js, call inject() in instrumentation.ts so it runs once per server start. Edge functions use load() instead, since there is no process.env to fill.
instrumentation.ts
```
import { inject } from "@envlet/sdk";

export async function register() {
  await inject();
}
```
05
Or say the word
With the Envlet MCP server in Claude Code, Cursor, or Codex, this whole guide is one sentence: move us to Envlet. The agent does every step above, and no value ever enters the conversation.
Claude Code
```
claude mcp add --scope user envlet -- npx -y @envlet/cli mcp
```

Stop pasting .env files.

One command. The right values for whoever runs it.