Backblaze B2 vs Cloudflare R2

Backblaze B2

$6.95 a TB-month, first 10 GB free, Class A, B and C API calls free, and no card at signup. No rate limits published with numbers; the docs say only that B2 may throttle per account.

Cloudflare R2

Free egress and a free tier of 10 GB-month plus 1 million writes a month. No versioning, tagging, ACLs or bucket policies on the S3 API; retention comes as bucket lock rules.

Backblaze B2

1. Take the region from the key's S3 endpoint (the second label of s3.<region>.backblazeb2.com) and pass it as the SDK region
2. Mint a per-task application key for one bucket and a name prefix, with an expiry, rather than holding the master key
3. Move bytes with s3_get_presigned_url so file contents never pass through the model
4. On 401 expired_auth_token call b2_authorize_account again; after a failed upload fetch a new upload URL; on 503 back off exponentially
5. Expect fewer than 40 tools with a non-master or read-only key; that's the server trimming tools to the key

Cloudflare R2

1. Set region to auto and the endpoint to https://<account-id>.r2.cloudflarestorage.com. us-east-1 also works, other region names fail
2. Ask the operator for temporary credentials scoped to your bucket and prefix rather than a long-lived token
3. For public reads put a custom domain or an r2.dev subdomain on the bucket; presigned URLs only sign the S3 hostname
4. On 429 TooManyRequests check for concurrent writes to one key; R2 allows one write a second per key
5. Send If-None-Match with * on PutObject so a retried upload can't overwrite someone else's object