Use the Bytescale JavaScript SDK to upload, transform, and serve files at scale.

Full SDK Documentation • Upload Widget • Media Processing APIs • Storage • CDN

Installation

For Node.js:

npm install @bytescale/sdk node-fetch

For Browsers:

npm install @bytescale/sdk

If you'd prefer to use a script tag:

<script src="https://js.bytescale.com/sdk/v3"></script>

Uploading Files — Try on CodePen

This library is isomorphic, meaning you can upload files from Node.js, or the browser, or both.

From Node.js:

import * as Bytescale from "@bytescale/sdk";
import nodeFetch from "node-fetch";

const uploadManager = new Bytescale.UploadManager({
  fetchApi: nodeFetch, // import nodeFetch from "node-fetch"; // Only required for Node.js. TypeScript: 'nodeFetch as any' may be necessary.
  apiKey: "free" // Get API keys from: www.bytescale.com
});

uploadManager
  .upload({
    // Supported types:
    // - String
    // - Blob
    // - ArrayBuffer
    // - Buffer
    // - ReadableStream (Node.js), e.g. fs.createReadStream("file.txt")
    data: "Hello World",

    // ---------
    // Optional:
    // ---------

    // Required if 'data' is a stream.
    // size: 5098, // e.g. fs.statSync("file.txt").size

    // Required if 'data' is a stream, buffer, or string.
    mime: "text/plain",

    // Required if 'data' is a stream, buffer, or string.
    originalFileName: "my_file.txt"

    // Reports progress: bytesTotal, bytesSent, progress.
    // onProgress: ({ progress }) => console.log(progress),

    // Controls multipart upload concurrency. Ignored if 'data' is a stream.
    // maxConcurrentUploadParts: 4,

    // Up to 2KB of arbitrary JSON.
    // metadata: {
    //   productId: 60891
    // },

    // Up to 25 tags per file.
    // tags: [
    //   "example_tag"
    // ],

    // About file paths:
    // - Your API key's "file upload path" is used by default, and can be changed by editing the API key's settings.
    // - You can override the API key's file upload path by specifying a path below.
    // - You may use path variables (e.g. "{UTC_DAY}"): http://localhost:3201/docs/path-variables
    // path: {
    //   folderPath: "/uploads/{UTC_YEAR}/{UTC_MONTH}/{UTC_DAY}",
    //   fileName: "{UTC_TIME_TOKEN_INVERSE}{UNIQUE_DIGITS_2}{ORIGINAL_FILE_EXT}"
    // },

    // Set to 'isCancelled = true' after invoking 'upload' to cancel the upload.
    // cancellationToken: {
    //   isCancelled: false
    // }
  })
  .then(
    ({ fileUrl, filePath }) => {
      // --------------------------------------------
      // File successfully uploaded!
      // --------------------------------------------
      // The 'filePath' uniquely identifies the file,
      // and is what you should save to your DB.
      // --------------------------------------------
      console.log(`File uploaded to: ${fileUrl}`);
    },
    error => console.error(`Error: ${error.message}`, error)
  );

From the Browser:

<html>
  <head>
    <script src="https://js.bytescale.com/sdk/v3"></script>
    <script>
      // import * as Bytescale from "@bytescale/sdk"
      const uploadManager = new Bytescale.UploadManager({
        apiKey: "free" // Get API keys from: www.bytescale.com
      });

      const onFileSelected = async event => {
        const file = event.target.files[0];

        try {
          const { fileUrl, filePath } = await uploadManager.upload({
            // Supported types:
            // - String
            // - Blob
            // - ArrayBuffer
            // - File (i.e. from a DOM file input element)
            data: file

            // ---------
            // Optional:
            // ---------

            // Required if 'data' is a stream. Node.js only. (Not required when uploading files from the browser.)
            // size: 5098, // e.g. fs.statSync("file.txt").size

            // Required if 'data' is a stream, buffer, or string. (Not required for DOM file inputs or blobs.)
            // mime: "application/octet-stream",

            // Required if 'data' is a stream, buffer, or string. (Not required for DOM file inputs or blobs.)
            // originalFileName: "my_file.txt",

            // Reports progress: bytesTotal, bytesSent, progress.
            // onProgress: ({ progress }) => console.log(progress),

            // Controls multipart upload concurrency. Ignored if 'data' is a stream.
            // maxConcurrentUploadParts: 4,

            // Up to 2KB of arbitrary JSON.
            // metadata: {
            //   productId: 60891
            // },

            // Up to 25 tags per file.
            // tags: [
            //   "example_tag"
            // ],

            // About file paths:
            // - Your API key's "file upload path" is used by default, and can be changed by editing the API key's settings.
            // - You can override the API key's file upload path by specifying a path below.
            // - You may use path variables (e.g. "{UTC_DAY}"): http://localhost:3201/docs/path-variables
            // path: {
            //   folderPath: "/uploads/{UTC_YEAR}/{UTC_MONTH}/{UTC_DAY}",
            //   fileName: "{UTC_TIME_TOKEN_INVERSE}{UNIQUE_DIGITS_2}{ORIGINAL_FILE_EXT}"
            // },

            // Set to 'isCancelled = true' after invoking 'upload' to cancel the upload.
            // cancellationToken: {
            //   isCancelled: false
            // }
          });

          // --------------------------------------------
          // File successfully uploaded!
          // --------------------------------------------
          // The 'filePath' uniquely identifies the file,
          // and is what you should save to your API.
          // --------------------------------------------
          alert(`File uploaded:\n${fileUrl}`);
        } catch (e) {
          alert(`Error:\n${e.message}`);
        }
      };
    </script>
  </head>
  <body>
    <input type="file" onchange="onFileSelected(event)" />
  </body>
</html>

Downloading Files

import * as Bytescale from "@bytescale/sdk";
import nodeFetch from "node-fetch"; // Only required for Node.js

const fileApi = new Bytescale.FileApi({
  fetchApi: nodeFetch, // import nodeFetch from "node-fetch"; // Only required for Node.js. TypeScript: 'nodeFetch as any' may be necessary.
  apiKey: "YOUR_API_KEY" // e.g. "secret_xxxxx"
});

fileApi
  .downloadFile({
    accountId: "YOUR_ACCOUNT_ID", // e.g. "W142hJk"
    filePath: "/uploads/2022/12/25/hello_world.txt"
  })
  .then(response => response.text()) // .text() | .json() | .blob() | .stream()
  .then(
    fileContents => console.log(fileContents),
    error => console.error(error)
  );

Use the UrlBuilder to get a URL instead (if you need a file URL instead of a binary stream).

Processing Files

import * as Bytescale from "@bytescale/sdk";
import fetch from "node-fetch"; // Only required for Node.js
import fs from "fs";

const fileApi = new Bytescale.FileApi({
  fetchApi: nodeFetch, // import nodeFetch from "node-fetch"; // Only required for Node.js. TypeScript: 'nodeFetch as any' may be necessary.
  apiKey: "YOUR_API_KEY" // e.g. "secret_xxxxx"
});

fileApi
  .processFile({
    accountId: "YOUR_ACCOUNT_ID", // e.g. "W142hJk"
    filePath: "/uploads/2022/12/25/image.jpg",

    // See: https://www.bytescale.com/docs/image-processing-api
    transformation: "image",
    transformationParams: {
      w: 800,
      h: 600
    }
  })
  .then(response => response.stream()) // .text() | .json() | .blob() | .stream()
  .then(
    imageByteStream =>
      new Promise((resolve, reject) => {
        const writer = fs.createWriteStream("image-thumbnail.jpg");
        writer.on("close", resolve);
        writer.on("error", reject);
        imageByteStream.pipe(writer);
      })
  )
  .then(
    () => console.log("Thumbnail saved to 'image-thumbnail.jpg'"),
    error => console.error(error)
  );

Use the UrlBuilder to get a URL instead (if you need a file URL instead of a binary stream).

Get File Details

import * as Bytescale from "@bytescale/sdk";
import fetch from "node-fetch"; // Only required for Node.js

const fileApi = new Bytescale.FileApi({
  fetchApi: nodeFetch, // import nodeFetch from "node-fetch"; // Only required for Node.js. TypeScript: 'nodeFetch as any' may be necessary.
  apiKey: "YOUR_API_KEY" // e.g. "secret_xxxxx"
});

fileApi
  .getFileDetails({
    accountId: "YOUR_ACCOUNT_ID", // e.g. "W142hJk"
    filePath: "/uploads/2022/12/25/image.jpg"
  })
  .then(
    fileDetails => console.log(fileDetails),
    error => console.error(error)
  );

Listing Folders

import * as Bytescale from "@bytescale/sdk";
import fetch from "node-fetch"; // Only required for Node.js

const folderApi = new Bytescale.FolderApi({
  fetchApi: nodeFetch, // import nodeFetch from "node-fetch"; // Only required for Node.js. TypeScript: 'nodeFetch as any' may be necessary.
  apiKey: "YOUR_API_KEY" // e.g. "secret_xxxxx"
});

folderApi
  .listFolder({
    accountId: "YOUR_ACCOUNT_ID", // e.g. "W142hJk"
    folderPath: "/",
    recursive: false
  })
  .then(
    // Note: operation is paginated, see 'result.cursor' and 'params.cursor'.
    result => console.log(`Items in folder: ${result.items.length}`),
    error => console.error(error)
  );

📙 Bytescale SDK API Reference

For a complete list of operations, please see:

Bytescale JavaScript SDK Docs »

🌐 Media Processing APIs (Image/Video/Audio)

Bytescale provides several real-time Media Processing APIs:

• Image Processing APIs (resize, crop, convert, compress & watermark)
• Video Processing APIs (transcode, optimize, resize & extract metadata)
• Audio Processing APIs (transcode, optimize, trim & extract metadata)

Image Processing API (Original Image)

Here's an example using a photo of Chicago:

https://upcdn.io/W142hJk/raw/example/city-landscape.jpg

Image Processing API (Transformed Image)

Using the Image Processing API, you can produce this image:

https://upcdn.io/W142hJk/image/example/city-landscape.jpg
  ?w=900
  &h=600
  &fit=crop
  &f=webp
  &q=80
  &blur=4
  &text=WATERMARK
  &layer-opacity=80
  &blend=overlay
  &layer-rotate=315
  &font-size=100
  &padding=10
  &font-weight=900
  &color=ffffff
  &repeat=true
  &text=Chicago
  &gravity=bottom
  &padding-x=50
  &padding-bottom=20
  &font=/example/fonts/Lobster.ttf
  &color=ffe400

Authentication

The Bytescale JavaScript SDK supports two types of authentication:

API Keys

The Bytescale JavaScript SDK automatically adds the apiKey from the constructor to the authorization header for all requests made via the SDK.

With API key auth, the requester has access to the resources available to the API key:

• Secret API keys (secret_***) can perform all API operations.

• Public API keys (public_***) can perform file uploads and file downloads only. File overwrites, file deletes, and all other destructive operations cannot be performed using public API keys.

Each Public API Key and Secret API Key can have its read/write access limited to a subset of files/folders.

JWTs

JWTs are optional.

With JWTs, the user can download private files directly via the URL, as authentication is performed implicitly via a session cookie or via an authorization header if service workers are enabled (see the serviceWorkerScript param on the AuthManager.beginAuthSession method). This allows the browser to display private files in <img>, <video>, and other elements.

With JWTs, the user can also perform API requests, such as file deletions, as these can be granted by the JWT's payload. The Bytescale JavaScript SDK will automatically inject the user's JWT into the authorization-token request header for all API requests, assuming the AuthManager.beginAuthSession method has been called.

Learn more about the AuthManager and JWTs »

Authenticate private URL aliases while keeping public CDN requests cacheable

Automatic (AuthSessionConfigAuto) and manual (AuthSessionConfigManual) configurations both accept requestUrlPrefixes?: string[]. This restricts service-worker authentication by matching the original event.request.url, before urlRewriteRules are applied. The rewritten destination must still match the configuration's CDN URL and account, and the configuration must not have expired.

• Omit the field (or set it to undefined) to preserve existing behavior.
• Set it to [] to authenticate no requests through the service worker.
• Provide multiple prefixes to match any of them using case-sensitive startsWith comparisons.

Prefixes follow the same string-array validation as sourceUrlPrefixes: they are not parsed or normalized. Use complete URL prefixes with a trailing / when restricting an origin or directory. An empty string matches any URL. sourceUrlPrefixes independently restricts the initiating page or iframe URL; when both fields are provided, both must match. Request prefixes alone do not require an initiating client, so new-tab downloads can use them.

Serve the current Bytescale auth service worker as /auth-sw.js on your application's origin, then initialize an automatic configuration:

import { AuthManager } from "@bytescale/sdk";

await AuthManager.beginAuthSession({
  serviceWorkerScript: "/auth-sw.js",
  urlRewriteRules: [
    { fromUrlPrefix: "https://app.example.com/media-auth/", toUrlPrefix: "https://upcdn.io/" },
    { fromUrlPrefix: "https://app.example.com/download/", toUrlPrefix: "https://upcdn.io/" }
  ],
  authConfigs: async () => [
    {
      accountId: "A123abc", // Replace with your Bytescale account ID.
      authConfigId: undefined,
      authUrl: "https://app.example.com/auth", // Your endpoint returning a JWT as text/plain.
      authHeaders: async () => ({}),
      requestUrlPrefixes: ["https://app.example.com/media-auth/", "https://app.example.com/download/"],
      enableCookieAuth: false
    }
  ]
});

For a manual configuration, replace authUrl and authHeaders with your getAuthorizationToken callback; keep requestUrlPrefixes and the other fields:

const manualConfig = {
  accountId: "A123abc",
  authConfigId: undefined,
  requestUrlPrefixes: ["https://app.example.com/media-auth/", "https://app.example.com/download/"],
  getAuthorizationToken: async () => {
    const response = await fetch("/auth");
    return await response.text();
  }
};

With the example configuration:

The download alias supports a normal link after initialization:

<a href="https://app.example.com/download/A123abc/raw/example.jpg?download=true" target="_blank" rel="noopener">
  Download
</a>

Rewriting uses the first matching rule once and continues even when authentication does not match. Responses remain streamed, and range headers, query parameters, and navigation behavior are preserved. A rejected request restriction allows the worker to consider later authentication entries. Existing rules preventing duplicate service-worker destinations within an AuthManager session still apply.

This field does not change API-client authentication, cookie authentication, token acquisition, or refresh. It does not remove caller-provided headers or existing CDN cookies. Leave cookie authentication disabled and avoid other broad authentication configurations for CDN requests you want to keep unauthenticated.

Compatibility and rollout: deploy the auth worker shipped with SDK 3.62.0 or later before enabling requestUrlPrefixes in the application. Update any self-hosted worker copies and allow the updated worker to activate in existing browser sessions. A distinct compatibility marker makes older workers skip the entire request-restricted configuration, even when sourceUrlPrefixes is also present. They cannot silently turn it into broad authentication. Private downloads may remain unauthenticated until the worker is updated; versions without rewrite support also cannot serve aliases. The updated worker can recover these restrictions and rewrite rules from persisted state after restart, and continues to support older configurations.

UrlBuilder

Use the UrlBuilder to construct URLs for your uploaded files:

import { UrlBuilder } from "@bytescale/sdk";

Raw Files

To get the URL for the uploaded image /example.jpg in its original form, use the following:

// Returns: "https://upcdn.io/1234abc/raw/example.jpg"
UrlBuilder.url({
  accountId: "1234abc",
  filePath: "/example.jpg"
});

Images

To resize the uploaded image /example.jpg to 800x600, use the following:

// Returns: "https://upcdn.io/1234abc/image/example.jpg?w=800&h=600"
UrlBuilder.url({
  accountId: "1234abc",
  filePath: "/example.jpg",
  options: {
    transformation: "image",
    transformationParams: {
      w: 800,
      h: 600
    }
  }
});

Image Processing API Docs »

Videos

To transcode the uploaded video /example.mov to MP4/H.264 in HD, use the following:

// Returns: "https://upcdn.io/1234abc/video/example.mov?f=mp4-h264&h=1080"
UrlBuilder.url({
  accountId: "1234abc",
  filePath: "/example.mov",
  options: {
    transformation: "video",
    transformationParams: {
      f: "mp4-h264",
      h: 1080
    }
  }
});

Video Processing API Docs »

Audio

To transcode the uploaded audio /example.wav to AAC in 192kbps, use the following:

// Returns: "https://upcdn.io/1234abc/audio/example.wav?f=aac&br=192"
UrlBuilder.url({
  accountId: "1234abc",
  filePath: "/example.wav",
  options: {
    transformation: "audio",
    transformationParams: {
      f: "aac",
      br: 192
    }
  }
});

Audio Processing API Docs »

Archives

To extract the file document.docx from the uploaded ZIP file /example.zip:

// Returns: "https://upcdn.io/1234abc/archive/example.zip?m=extract&artifact=/document.docx"
UrlBuilder.url({
  accountId: "1234abc",
  filePath: "/example.zip",
  options: {
    transformation: "archive",
    transformationParams: {
      m: "extract"
    },
    artifact: "/document.docx"
  }
});

Archive Processing API Docs »

Antivirus

To scan the file example.zip for viruses, use the following:

// Returns: "https://upcdn.io/1234abc/antivirus/example.zip"
UrlBuilder.url({
  accountId: "1234abc",
  filePath: "/example.zip",
  options: {
    transformation: "antivirus"
  }
});

Antivirus API Docs »

🙋 Can I use my own storage?

Bytescale supports AWS S3, Cloudflare R2, Google Storage, DigitalOcean, and Bytescale Storage.

Bytescale Storage Docs »

Bytescale JavaScript SDK Docs »

👋 Create your Bytescale Account

Bytescale is the best way to upload, transform, and serve images, videos, and audio at scale.

Create a Bytescale account »

License

MIT