Authentication

The SDK authenticates with your Custodian Labs API key, sent as an X-API-Key header. You can provide it with an environment variable or a constructor option.

Environment variables

Variable	Default	Purpose
CUSTODIAN_SDK_API_KEY	—	API key for assistant / agent calls
CUSTODIAN_SDK_BASE_URL	https://platform.custodianlabs.io/v1	Override the Platform API host
CUSTODIAN_MASKING_BASE_URL	https://privacy.custodianlabs.io	Override the Guardian Layer host

Legacy aliases AI_SDK_API_KEY and AI_SDK_BASE_URL are still read for backwards compatibility.

export CUSTODIAN_SDK_API_KEY="custodian_labs_xxxxxxxx"

import { createCustodian } from "@custodianlabs/sdk";

// Key picked up from CUSTODIAN_SDK_API_KEY
const app = await createCustodian({ model: "gpt-4o", prompt: "You are helpful." });

Constructor options

Any of the values above can be passed explicitly instead:

import { Custodian } from "@custodianlabs/sdk";

const custodian = new Custodian({
  model: "gpt-4o",
  systemPrompt: "You are a helpful assistant",
  apiKey: process.env.MY_KEY,
  baseUrl: "https://platform.custodianlabs.io/v1",
  timeout: 30,      // seconds
  maxRetries: 2,
});

Keep your key server-side

Do not ship your API key to the browser. Call the SDK from a backend, serverless function, or edge handler, and expose only the results to your frontend.

Next step

Continue to Create your first Custodian.