Cloudflare R2 Setup Guide

Configure an R2 bucket, API token, CORS policy, and ShrimpSend settings.

When to use R2

• S3-compatible storage with favorable egress pricing.
• You manage your own R2 bucket and keys on Cloudflare.

Get started

1. Sign in to the Cloudflare Dashboard.
2. Open Build → Storage & databases → R2 object storage → Overview.

S3 API endpoint

On the R2 Overview page, under Account details:

• Account ID — may appear in the endpoint URL.
• S3 API — this is your ShrimpSend Endpoint (https://<accountid>.r2.cloudflarestorage.com). Use the copy button.

Click API token → Manage to create keys.

Create an API token

1. Go to R2 object storage → Manage R2 API tokens (or API token → Manage from account details).
2. For personal use, click Create User API token.
3. Grant Object Read & Write scoped to your bucket.
4. Save Access Key ID and Secret Access Key (secret shown once).

Create a bucket

1. On R2 Overview, click + Create bucket.
2. Enter a globally unique name.
3. Keep Automatic location and Standard storage class unless you have other needs.
4. Click Create bucket (buckets are private by default).

Configure CORS

Browser uploads require CORS:

1. Open the bucket → Settings tab.
2. Select CORS policy → Edit.
3. Paste the JSON below and save.

[
  {
    "AllowedOrigins": [
      "https://xiachuan.net",
      "https://www.xiachuan.net"
    ],
    "AllowedMethods": [
      "GET",
      "PUT",
      "POST",
      "DELETE",
      "HEAD"
    ],
    "AllowedHeaders": [
      "*"
    ],
    "ExposeHeaders": [
      "ETag",
      "Content-Length"
    ],
    "MaxAgeSeconds": 86400
  }
]

ShrimpSend settings

Open S3 configuration from either entry point:

1. Settings → S3 — global config for all devices on the account.
2. S3 cloud relay session — use S3 settings inside the session.

Test connection

Run Test connection, then send a file across networks. Check DevTools if uploads fail with CORS errors.

FAQ

Region? Use auto.

403 / signature errors? Verify token scope, endpoint, and Path-style.

Built-in S3 vs your R2? Built-in is platform-hosted; this guide is for your own R2 bucket.