Secrets

Workers can use API keys and credentials without exposing them to the frontend. Secrets are set via MCP tools and accessed in worker code through a safe API.

Setting secrets

// Personal secret — available to all your worker spaces
set_secret({ name: "OPENAI_KEY", value: "sk-..." })

// Org secret — shared across all spaces in the org
set_secret({ name: "OPENAI_KEY", value: "sk-...", scope: "org", org: "my-team" })

// Restrict where the secret can be sent
set_secret({
  name: "OPENAI_KEY",
  value: "sk-...",
  allowed_urls: ["https://api.openai.com/"]
})

Using secrets in worker code

export default {
  async fetch(request, env) {
    const key = await env.secrets.get("OPENAI_KEY");
    const allNames = await env.secrets.list();

    // Use in API calls — safe, stays server-side
    const resp = await fetch("https://api.openai.com/v1/chat/completions", {
      headers: { "Authorization": "Bearer " + key },
      // ...
    });
  }
};

Safety layers

• Isolated API — secrets are NOT on env directly. JSON.stringify(env) and Object.keys(env) won't reveal them. Access only via env.secrets.get(name).
• Fetch interception — if a secret has allowed_urls, outbound fetch() calls are inspected. Requests containing the secret sent to non-allowed URLs are blocked (403).
• Response redaction — text and JSON response bodies are scanned for secret values. Matches are replaced with [REDACTED] before reaching the browser.