Tools & SDKs

JavaScript (AWS SDK v3)

Use the modular AWS SDK v3 packages. They work in Node, Deno, Bun, and the browser. The only change from real S3 is the endpoint and forcePathStyle: true.

Install

npm install @aws-sdk/client-s3 @aws-sdk/s3-request-presigner

Client setup

import { S3Client } from "@aws-sdk/client-s3";

export const s3 = new S3Client({
  region: "us-east-1",
  endpoint: "https://s3.uploom.io",
  forcePathStyle: true,
  credentials: {
    accessKeyId: process.env.UPLOOM_ACCESS_KEY!,
    secretAccessKey: process.env.UPLOOM_SECRET!,
  },
});

List buckets and objects

import { ListBucketsCommand, ListObjectsV2Command } from "@aws-sdk/client-s3";

const { Buckets } = await s3.send(new ListBucketsCommand({}));
console.log(Buckets);

const { Contents } = await s3.send(new ListObjectsV2Command({
  Bucket: "bucket",
  Prefix: "photos/",
}));
console.log(Contents);

Upload (single-part)

import { PutObjectCommand } from "@aws-sdk/client-s3";

await s3.send(new PutObjectCommand({
  Bucket: "bucket",
  Key: "photos/2026/photo.jpg",
  Body: file,
  ContentType: "image/jpeg",
}));

Download

import { GetObjectCommand } from "@aws-sdk/client-s3";

const { Body } = await s3.send(new GetObjectCommand({
  Bucket: "bucket",
  Key: "photos/2026/photo.jpg",
}));

// Node
const bytes = await Body.transformToByteArray();

// Browser
const blob = await Body.blob();

Multipart

import { Upload } from "@aws-sdk/lib-storage";

await new Upload({
  client: s3,
  params: { Bucket: "bucket", Key: "backups/huge.bin", Body: file },
}).done();

Presigned URL

import { PutObjectCommand } from "@aws-sdk/client-s3";
import { getSignedUrl } from "@aws-sdk/s3-request-presigner";

const url = await getSignedUrl(
  s3,
  new PutObjectCommand({
    Bucket: "bucket",
    Key: `uploads/${crypto.randomUUID()}.bin`,
  }),
  { expiresIn: 600 },
);

// In the browser:
await fetch(url, { method: "PUT", body: file });

Bundle size

The SDK is tree-shakable. Importing just @aws-sdk/client-s3 with the commands you need keeps the bundle around 60 kB gzipped. @aws-sdk/s3-request-presigner is an extra ~5 kB.

Edge runtimes

The SDK works on all modern JS runtimes. For Cloudflare Workers, Deno, or Bun, the default FetchHttpHandler is fine. The Body of GetObjectCommand is always a Web ReadableStream.