> ## Documentation Index
> Fetch the complete documentation index at: https://unkey.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Unkey is two separate products. Compute builds, deploys, and runs apps behind a gateway. API Management issues API keys, enforces rate limits, manages identities and permissions, and reports usage. Say which product a page belongs to; a reader can use either without the other.
> Every Unkey API endpoint is an HTTP POST to https://api.unkey.com/v2/{service}.{procedure} with a root key in the Authorization: Bearer header. Root keys are workspace scoped.
> Error codes have the form err:{system}:{category}:{specific} and each has a page at /errors/{system}/{category}/{specific}.
> The word environment means production or preview in Compute. Rate limiting has four meanings on this site; the glossary lists them.

# Express guide

> Protect Express routes with API key middleware.

export const versions = {
  cli: "2.0.150",
  tsApi: "2.5.1",
  tsRatelimit: "2.1.4",
  tsHono: "2.0.0",
  tsNextjs: "2.0.0",
  tsCache: "1.5.0",
  tsNuxt: "1.1.15",
  goSdk: "v3.0.1",
  pySdk: "3.0.3"
};

Protect Express routes with API keys. A middleware reads the bearer token, calls `keys.verifyKey`, rejects bad keys with the right status, and puts the result on `res.locals.unkey` for your handlers.

<Note>
  You need a root key with the permissions listed on this page. Create one in the dashboard under **Settings > Root Keys**, and pass it as `Authorization: Bearer <root key>`. See [Permission reference](/docs/platform/root-keys/permissions-legacy) for every permission.
</Note>

<Steps titleSize="h3">
  <Step title="Create a root key and a keyspace">
    In the dashboard, go to **Settings > Root Keys** and create a root key with `api.*.create_api`, `api.*.create_key`, and `api.*.verify_key`. Put it in your server's `UNKEY_ROOT_KEY` environment variable. Never send it to a browser or mobile app.

    Then create a keyspace, which holds your keys. Use **Keyspaces (APIs)** in the dashboard, or `apis.createApi`:

    ```bash create a keyspace theme={"theme":"kanagawa-wave"}
    curl -X POST https://api.unkey.com/v2/apis.createApi \
      -H "Authorization: Bearer $UNKEY_ROOT_KEY" \
      -H "Content-Type: application/json" \
      -d '{ "name": "my-api" }'
    ```

    Keep the `data.apiId` from the response. You need it to create keys. See [Root keys](/docs/platform/root-keys/overview) for more on root keys.
  </Step>

  <Step title="Install the SDK">
    `@unkey/api` (version {versions.tsApi}) is the client for the whole API.

    <CodeGroup>
      ```bash npm theme={"theme":"kanagawa-wave"}
      npm install @unkey/api express
      ```

      ```bash pnpm theme={"theme":"kanagawa-wave"}
      pnpm add @unkey/api express
      ```
    </CodeGroup>
  </Step>

  <Step title="Create a key for a user">
    Create a key from your backend when a user signs up or asks for one. `externalId` links the key to the user, so verification tells you who's calling. `meta` comes back on every verification. You get `data.key` only once: show it to the user and store only `data.keyId`.

    <CodeGroup>
      ```bash curl theme={"theme":"kanagawa-wave"}
      curl -X POST https://api.unkey.com/v2/keys.createKey \
        -H "Authorization: Bearer $UNKEY_ROOT_KEY" \
        -H "Content-Type: application/json" \
        -d '{ "apiId": "api_...", "prefix": "sk_live", "externalId": "user_123", "meta": { "plan": "free" } }'
      ```

      ```ts TypeScript theme={"theme":"kanagawa-wave"}
      import { Unkey } from "@unkey/api";

      const unkey = new Unkey({ rootKey: process.env.UNKEY_ROOT_KEY ?? "" });

      const created = await unkey.keys.createKey({
        apiId: process.env.UNKEY_API_ID ?? "",
        prefix: "sk_live",
        externalId: "user_123",
        meta: { plan: "free" },
      });
      // created.data.key is the plaintext, created.data.keyId the handle you keep
      ```
    </CodeGroup>

    Every field is described in [Creating keys](/docs/api-management/keys/creating-keys).
  </Step>

  <Step title="Verify the key in a middleware">
    The middleware <Tooltip tip="Here: keys.verifyKey checking a key your user presented. Not domain verification and not the gateway policy.">verifies</Tooltip> the key once per request and puts the result on `res.locals.unkey`. Routes that need extra permissions pass a `permissions` query.

    Keep `next()` outside the `try`. Otherwise an error in a route handler is caught here and answered as a 503 authentication failure.

    ```ts src/unkey.ts theme={"theme":"kanagawa-wave"}
    import { Unkey } from "@unkey/api";
    import * as errors from "@unkey/api/models/errors";
    import type { V2KeysVerifyKeyResponseBody } from "@unkey/api/models/components";
    import type { NextFunction, Request, Response } from "express";

    const unkey = new Unkey({ rootKey: process.env.UNKEY_ROOT_KEY ?? "" });

    export function requireKey(permissions?: string) {
      return async (req: Request, res: Response, next: NextFunction) => {
        const auth = req.header("authorization") ?? "";
        const key = auth.startsWith("Bearer ") ? auth.slice("Bearer ".length) : "";
        if (!key) {
          return res.status(401).json({ error: "missing API key" });
        }

        let result: V2KeysVerifyKeyResponseBody;
        try {
          result = await unkey.keys.verifyKey({
            key,
            permissions,
            tags: [`endpoint=${req.path}`, `method=${req.method}`],
          });
        } catch (err) {
          if (err instanceof errors.UnkeyError) {
            console.error("unkey", err.statusCode, err.message);
          }
          return res.status(503).json({ error: "authentication unavailable" });
        }

        if (!result.data.valid) {
          return res.status(statusFor(result.data.code)).json({ error: result.data.code });
        }
        res.locals.unkey = result.data;
        next();
      };
    }

    function statusFor(code: string): number {
      switch (code) {
        case "RATE_LIMITED":
          return 429;
        case "USAGE_EXCEEDED":
          return 402;
        case "FORBIDDEN":
        case "INSUFFICIENT_PERMISSIONS":
          return 403;
        default:
          return 401;
      }
    }
    ```

    ```ts src/server.ts theme={"theme":"kanagawa-wave"}
    import express from "express";
    import { requireKey } from "./unkey";

    const app = express();

    app.get("/items", requireKey(), (_req, res) => {
      res.json({ items: [], owner: res.locals.unkey.identity?.externalId });
    });

    app.post("/items", requireKey("items.write"), (_req, res) => {
      res.status(201).json({ ok: true });
    });

    app.listen(3000);
    ```

    ```bash theme={"theme":"kanagawa-wave"}
    curl http://localhost:3000/items -H "Authorization: Bearer sk_live_..."
    ```
  </Step>

  <Step title="Handle the outcome codes">
    `keys.verifyKey` returns HTTP 200 for every outcome. Check `data.valid`, then `data.code` for the reason, and return the matching status from your API:

    | `data.code` | Meaning | Return |
    | - | - | - |
    | `VALID` | Every check passed. | continue |
    | `NOT_FOUND` | No such key, or your root key may not verify this keyspace. | 401 |
    | `DISABLED` | The key was disabled. | 401 |
    | `EXPIRED` | The key's expiry passed. | 401 |
    | `FORBIDDEN` | Client IP not on the keyspace allow list, or the workspace is disabled. | 403 |
    | `INSUFFICIENT_PERMISSIONS` | The `permissions` query was not satisfied. | 403 |
    | `RATE_LIMITED` | A <Tooltip tip="Here: limits enforced by keys.verifyKey on a key or identity, or by the standalone ratelimit API. Not a Compute gateway policy.">rate limit</Tooltip> on the key or its identity was exceeded. | 429 |
    | `USAGE_EXCEEDED` | The key has no credits left. | 402 or 429 |

    Remaining credits are in `data.credits`, and each checked rate limit is in `data.ratelimits` with `remaining` and `reset`. The call only fails with an HTTP error (which the SDKs throw) when the call itself is wrong, such as a bad root key or a malformed body. See [Verifying keys](/docs/api-management/keys/verifying-keys) for every field.
  </Step>

  <Step title="Next steps">
    <Columns cols={2}>
      <Card title="Verifying keys" href="/docs/api-management/keys/verifying-keys" icon="key">Every request field, the order of checks, and every response field.</Card>
      <Card title="Credits and refill" href="/docs/api-management/keys/credits-and-refill" icon="coins">Meter usage per key and refill balances on a schedule.</Card>
      <Card title="Cookbook" href="/docs/api-management/cookbook/index" icon="book">Copy-ready recipes for rate limits, billing, and subscription tiers.</Card>
    </Columns>
  </Step>
</Steps>