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A lightweight S3 client.

Works with
This package works with Bun
It is unknown whether this package works with Cloudflare Workers
This package works with Node.js
This package works with Deno
This package works with Browsers
JSR Score
2 weeks ago (0.7.6)


This is a lightweight S3 client for Deno and other modern JavaScript runtimes. It is designed to offer all the key features you may need, with no dependencies outside of the Deno standard library. It does not use any Deno-specific features, so it should work with any runtime that supports the fetch API, web streams API, and ES modules (ESM).

This client is 100% MIT licensed, and is derived from the excellent MinIO JavaScript Client.

Supported functionality:

  • Authenticated or unauthenticated requests
  • List objects: for await (const object of client.listObjects(options)) { ... }
    • Handles pagination transparently
    • Supports filtering using a prefix
    • Supports grouping using a delimiter (use client.listObjectsGrouped(...))
  • Check if an object exists: client.exists("key")
  • Get metadata about an object: client.statObject("key")
  • Download an object: client.getObject("key", options)
    • This just returns a standard HTTP Response object, so for large files, you can opt to consume the data as a stream (use the .body property).
  • Download a partial object: client.getPartialObject("key", options)
    • Like getObject, this also supports streaming the response if you want to.
  • Upload an object: client.putObject("key", streamOrData, options)
    • Can upload from a string, Uint8Array, or ReadableStream
    • Can split large uploads into multiple parts and uploads parts in parallel.
    • Can set custom headers, ACLs, and other metadata on the new object (example below).
  • Copy an object: client.copyObject({ sourceKey: "source", options }, "dest", options)
    • Can copy between different buckets.
  • Delete an object: client.deleteObject("key")
  • Create pre-signed URLs: client.presignedGetObject("key", options) or client.getPresignedUrl(method, "key", options)
  • Check if a bucket exists: client.bucketExists("bucketName")
  • Create a new bucket: client.makeBucket("bucketName")
  • Remove a bucket: client.removeBucket("bucketName")


JSR Version JSR Score

  • Deno: deno add @bradenmacdonald/s3-lite-client
  • Deno (no install): import { S3Client } from "jsr:@bradenmacdonald/s3-lite-client@0.7.6";
  • NPM: npx jsr add @bradenmacdonald/s3-lite-client
  • Yarn: yarn dlx jsr add @bradenmacdonald/s3-lite-client
  • pnpm: pnpm dlx jsr add @bradenmacdonald/s3-lite-client
  • Bun: bunx jsr add @bradenmacdonald/s3-lite-client
  • Browser:
    <script type="module">
      import { S3Client } from "";
      // Or:
      const { S3Client } = await import('');

Note: if you're using Node.js, this only works on Node 19+.

Usage Examples (Quickstart)

List data files from a public data set on Amazon S3:

import { S3Client } from "@bradenmacdonald/s3-lite-client";

const s3client = new S3Client({
  endPoint: "",
  port: 443,
  useSSL: true,
  region: "us-east-1",
  bucket: "openalex",
  pathStyle: false,

// Log data about each object found under the 'data/concepts/' prefix:
for await (const obj of s3client.listObjects({ prefix: "data/concepts/" })) {
// {
//   type: "Object",
//   key: "data/concepts/updated_date=2024-01-25/part_000.gz",
//   etag: "2c9b2843c8d2e9057656e1af1c2a92ad",
//   size: 44105,
//   lastModified: 2024-01-25T22:57:43.000Z
// },
// ...

// Or, to get all the keys (paths) as an array:
const keys = await Array.fromAsync(s3client.listObjects(), (entry) => entry.key);
// keys = [
//  "data/authors/manifest",
//  "data/authors/updated_date=2023-06-08/part_000.gz",
//  ...
// ]

Uploading and downloading a file using a local MinIO server:

import { S3Client } from "@bradenmacdonald/s3-lite-client";

// Connecting to a local MinIO server:
const s3client = new S3Client({
  endPoint: "localhost",
  port: 9000,
  useSSL: false,
  region: "dev-region",
  accessKey: "AKIA_DEV",
  secretKey: "secretkey",
  bucket: "dev-bucket",
  pathStyle: true,

// Upload a file:
await s3client.putObject("test.txt", "This is the contents of the file.");

// Now download it
const result = await s3client.getObject("test.txt");
// and stream the results to a local file:
const localOutFile = await"test-out.txt", { write: true, createNew: true });
await result.body!.pipeTo(localOutFile.writable);
// or instead of streaming, you can consume the whole file into memory by awaiting
// result.text(), result.blob(), result.arrayBuffer(), or result.json()

Set ACLs, Content-Type, custom metadata, etc. during upload:

await s3client.putObject("key", streamOrData, {
  metadata: {
    "x-amz-acl": "public-read",
    "x-amz-meta-custom": "value",

For more examples, check out the tests in integration.ts

Developer notes

To run the tests, please use:

deno lint && deno test

To format the code, use:

deno fmt

To run the integration tests, first start MinIO with this command:

docker run --rm -e MINIO_ROOT_USER=AKIA_DEV -e MINIO_ROOT_PASSWORD=secretkey -e MINIO_REGION_NAME=dev-region -p 9000:9000 -p 9001:9001 --entrypoint /bin/sh minio/minio:RELEASE.2021-10-23T03-28-24Z -c 'mkdir -p /data/dev-bucket && minio server --console-address ":9001" /data'

Then while MinIO is running, run

deno test --allow-net integration.ts

(If you encounter issues and need to debug what MinIO is seeing, run these two commands:)

mc alias set localdebug http://localhost:9000 AKIA_DEV secretkey
mc admin trace --verbose --all localdebug
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