File posting

axios makes file uploads straightforward. Use postForm or FormData when you need multipart/form-data uploads.

Single file (browser)

Pass a File object directly as a field value — axios will detect it and use the correct content type automatically:

await axios.postForm("https://httpbin.org/post", {
  description: "My profile photo",
  file: document.querySelector("#fileInput").files[0],
});

Multiple files (browser)

Pass a FileList to upload all selected files at once. They will all be sent under the same field name (files[]):

await axios.postForm(
  "https://httpbin.org/post",
  document.querySelector("#fileInput").files
);

To use distinct field names for each file, build a FormData object manually:

const formData = new FormData();
formData.append("avatar", avatarFile);
formData.append("cover", coverFile);

await axios.post("https://httpbin.org/post", formData);

Tracking upload progress (browser)

Use the onUploadProgress callback to show a progress bar or percentage to your users:

await axios.postForm("https://httpbin.org/post", {
  file: document.querySelector("#fileInput").files[0],
}, {
  onUploadProgress: (progressEvent) => {
    const percent = Math.round(
      (progressEvent.loaded * 100) / progressEvent.total
    );
    console.log(`Upload progress: ${percent}%`);
  },
});

See Progress capturing for the full list of fields available on the progress event.

Files in Node.js

In Node.js, use fs.createReadStream to upload a file from the filesystem without loading it entirely into memory:

import fs from "fs";
import FormData from "form-data";
import axios from "axios";

const form = new FormData();
form.append("file", fs.createReadStream("/path/to/file.jpg"));
form.append("description", "My uploaded file");

await axios.post("https://httpbin.org/post", form);

TIP

The form-data npm package is required in Node.js environments to create FormData objects. In modern Node.js (v18+), the global FormData is available natively.

Uploading a Buffer (Node.js)

You can also upload an in-memory Buffer directly:

const buffer = Buffer.from("Hello, world!");

const form = new FormData();
form.append("file", buffer, {
  filename: "hello.txt",
  contentType: "text/plain",
  knownLength: buffer.length,
});

await axios.post("https://httpbin.org/post", form);

WARNING

Capturing FormData upload progress is not currently supported in Node.js environments.

DANGER

When uploading a readable stream in Node.js, set maxRedirects: 0 to prevent the follow-redirects package from buffering the entire stream in RAM.