Secure Your OpenAI API Key in Next.js

The Problem

This is what most Next.js codebases look like today. The OPENAI_API_KEY key (sk-proj-...) lives directly in the process environment. If your repo, your CI logs, or your deployment config leaks — so does your key.

// app/api/chat/route.ts  ← your real key leaves your server on every call
import OpenAI from "openai";

const openai = new OpenAI({
  apiKey: process.env.OPENAI_API_KEY, // sk-proj-YOUR_REAL_KEY stored in .env.local
});

export async function POST(req: Request) {
  const { messages } = await req.json();

  const completion = await openai.chat.completions.create({
    model: "gpt-4o",
    messages,
  });

  return Response.json(completion.choices[0].message);
}

The Fix

Send the request to the KeyVault Edge proxy at https://proxy.keyvaultedge.com with the provider's usual path, your kvt_ token in X-KV-Token and the provider's base URL in X-KV-Target. The proxy refuses requests whose Origin isn't on the token's allowed hosts, then injects your real OPENAI_API_KEY, so it never sits in your app's environment.

// app/api/chat/route.ts  ← real key never in this process; KVE_TOKEN is host-bound
export async function POST(req: Request) {
  const { messages } = await req.json();

  const response = await fetch("https://proxy.keyvaultedge.com/v1/chat/completions", {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "X-KV-Token": process.env.KVE_TOKEN!, // kvt_... token, server-side only
      "X-KV-Target": "https://api.openai.com",
      // Must match one of the token's allowed hosts
      Origin: process.env.APP_ORIGIN!,
    },
    body: JSON.stringify({
      model: "gpt-4o",
      messages,
    }),
  });

  const data = await response.json();
  return Response.json(data.choices[0].message);
}

Setup in 4 steps

# .env.local
KVE_TOKEN=kvt_...your_token
APP_ORIGIN=https://yourdomain.com  # one of the token's allowed hosts

# Vercel CLI (production)
vercel env add KVE_TOKEN production

What this protects, and what it doesn't

• Your real OPENAI_API_KEY stays at the edge, so it can't leak from your repo, logs, bundle or server environment.
• The kvt_ token is still a credential. A copied token can be replayed by anyone who can send the right headers, including a fake Origin from a server. The protection is that each token has its own rate limits, monthly cost cap and endpoint scope, and you can revoke it in one click without rotating the provider key.
• The cost cap is estimated from the usage the provider reports, so a request already in flight can overshoot it slightly.

More on layered defences in how to protect your OpenAI API key. Plans and limits are on the pricing page.

More OpenAI guides