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You can connect Cloudflare R2 as S3-compatible storage in Syne by creating buckets, generating access credentials, and filling out the storage form.
Cloudflare R2 is fully S3-compatible, so you connect it by creating an R2 bucket, generating an R2 API token (Access Key / Secret), and using the R2 S3 endpoint.

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Step 1 – Create an R2 bucket

  1. In the Cloudflare dashboard, go to R2 → Object Storage.
  2. Click Create bucket, choose a bucket name (for example syne-r2-data), and finish the wizard.
  3. Keep the bucket private by default; do not enable public access unless you explicitly need it.

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Step 2 – Generate S3 API credentials (Access Key / Secret)

R2 uses API tokens that map to S3-compatible Access Key ID and Secret Access Key values.

Create an R2 API token

  • In the Cloudflare dashboard, go to R2 → Object Storage → Manage R2 API Tokens.
  • Click Create API Token and choose a template that grants access only to the buckets Syne should use (least privilege).
  • After creation, Cloudflare will show you:
    • Access Key ID
    • Secret Access Key
      These are displayed once; copy and store them securely.
Use these as your Access Key and Secret Key in Syne.

Find the R2 S3 endpoint

  • In R2 → Object Storage, copy your Account ID from the overview.
  • Open your bucket → Settings → S3 API.
  • Copy the endpoint URL. It typically looks like:
    https://<ACCOUNT_ID>.r2.cloudflarestorage.com
    This is the value for the Endpoint field in Syne.
  • When a region is required, you can use auto or APAC, which R2 aliases to its automatic region for S3 compatibility.

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Step 3 – Fill out the Syne storage form (R2)

2025 12 22 11 38 33 Use the S3-compatible option in Syne and set:
  • Storage Name
    • Any label, for example R2_BACKUPS.
  • Bucket Name
    • Your R2 bucket name, e.g. syne-r2-data.
  • Endpoint
    • The R2 S3 endpoint: https://<ACCOUNT_ID>.r2.cloudflarestorage.com.
  • Region
    • Use auto or APAC (recommended for R2).
  • Access Key
    • The Access Key ID from your R2 API token.
  • Secret Key
    • The Secret Access Key from the same token.
  • Path Prefix (optional)
    • Optional folder-like prefix, e.g. syne/.
  • Public
    • Keep off so objects remain private; manage access through Cloudflare permissions instead.
That’s it now, you should be able to dump backup files, uploaded files over to your own buckets.