Cloudflare R2 vs AWS S3: Full Comparison for Developers (2026)

Amazon S3 has long been the dominant cloud object storage solution, but its data egress (bandwidth) fees remain a significant cost pain point for high-traffic download platforms. Cloudflare R2 entered the market with full S3 API compatibility and zero egress fees. Here is an architectural and financial breakdown.

Core Architectural Differences

Code Migration: Connecting to R2 with AWS SDK v3

Migrating from S3 to R2 requires changing only the client endpoint:

import { S3Client, PutObjectCommand } from '@aws-sdk/client-s3';

const r2Client = new S3Client({
  region: 'auto',
  endpoint: `https://${process.env.CLOUDFLARE_ACCOUNT_ID}.r2.cloudflarestorage.com`,
  credentials: {
    accessKeyId: process.env.R2_ACCESS_KEY_ID!,
    secretAccessKey: process.env.R2_SECRET_ACCESS_KEY!,
  },
});

export async function uploadToR2(bucket: string, key: string, data: Buffer) {
  return await r2Client.send(
    new PutObjectCommand({
      Bucket: bucket,
      Key: key,
      Body: data,
    })
  );
}

When to Choose Which?

• Choose Cloudflare R2: For public file distributions, software releases, game patchers, and video assets where download egress dominates your AWS bill.
• Choose AWS S3: If your application relies deeply on AWS services like Athena, SageMaker, or fine-grained IAM resource tagging.