Adapters

Adapters allow you to customize the way axios handles the request data. By default, axios uses an ordered priority list of ['xhr', 'http', 'fetch'] and selects the first adapter that is supported by the current environment. In practice this means xhr is used in browsers, http in Node.js, and fetch in environments where neither is available (such as Cloudflare Workers or Deno).

Writing your own adapter lets you fully control how axios makes a request and processes the response — useful for testing, custom transports, or non-standard environments.

Built-in adapters

You can select a built-in adapter by name using the adapter config option:

// Use the fetch adapter
const instance = axios.create({ adapter: "fetch" });

// Use the XHR adapter (browser default)
const instance = axios.create({ adapter: "xhr" });

// Use the HTTP adapter (Node.js default)
const instance = axios.create({ adapter: "http" });

You can also pass an array of adapter names. axios will use the first one supported by the current environment:

const instance = axios.create({ adapter: ["fetch", "xhr", "http"] });

For more details on the fetch adapter, see the Fetch adapter page.

Creating a custom adapter

To create a custom adapter, write a function that accepts a config object and returns a Promise that resolves to a valid axios response object.

import axios from "axios";
import { settle } from "axios/unsafe/core/settle.js";

function myAdapter(config) {
  /**
   * At this point:
   * - config has been merged with defaults
   * - request transformers have run
   * - request interceptors have run
   *
   * The adapter is now responsible for making the request
   * and returning a valid response object.
   */

  return new Promise((resolve, reject) => {
    // Perform your custom request logic here.
    // This example uses the native fetch API as a starting point.
    fetch(config.url, {
      method: config.method?.toUpperCase() ?? "GET",
      headers: config.headers?.toJSON() ?? {},
      body: config.data,
      signal: config.signal,
    })
      .then(async (fetchResponse) => {
        const responseData = await fetchResponse.text();

        const response = {
          data: responseData,
          status: fetchResponse.status,
          statusText: fetchResponse.statusText,
          headers: Object.fromEntries(fetchResponse.headers.entries()),
          config,
          request: null,
        };

        // settle resolves or rejects the promise based on the HTTP status
        settle(resolve, reject, response);

        /**
         * After this point:
         * - response transformers will run
         * - response interceptors will run
         */
      })
      .catch(reject);
  });
}

const instance = axios.create({ adapter: myAdapter });

TIP

The settle helper resolves the promise for 2xx status codes and rejects it for everything else, matching axios's default behaviour. If you want custom status validation, use the validateStatus config option instead.