Backblaze B2 vs Wasabi Hot Cloud Storage

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.

Wasabi Hot Cloud Storage

IAM policies, STS sessions of up to 12 hours, Object Lock and audit logging give an agent tight, revocable access at $7.99 a TB-month with no egress or request fees. No request limits are published with numbers for the S3 API, there is no OpenAPI file, and billing assumes 1 TB and 90 days of storage as minimums.

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

Wasabi Hot Cloud Storage

1. Use the bucket's own regional endpoint, such as s3.eu-central-2.wasabisys.com. The docs say a wrong endpoint allows GET but not PUT or DELETE
2. Ask for a sub-user key with a policy limited to one bucket, or an STS session. A root key has full access, billing included
3. Avoid short-lived objects. Each object deleted before 90 days is billed for the remaining days, and objects under 4 KB bill as 4 KB
4. Keep monthly downloads at or below the stored volume, the limit of the free egress policy
5. Call https:// endpoints explicitly. The S3 API also accepts plain HTTP
6. For the MCP beta, type https://mcp.wasabisys.dev/s3 from the page text. The links in the docs table point at a different host