Backblaze B2 vs Dropbox API + MCP

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.

Dropbox API + MCP

Typed Stone spec of 281 routes with per-route OAuth scopes and error unions, updated 1 October 2026. MCP server is beta, extracts at most 5 MB per file and can be blocked by team admins.

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

Dropbox API + MCP

1. Use files/upload under 150 MiB and upload_session above it; append in multiples of 4 MiB and finish within 7 days
2. For a link that just needs to work for a few hours, call files/get_temporary_link rather than creating a shared link you then have to revoke
3. Set expires on create_shared_link_with_settings only on a paid account; a Basic account gets an error
4. Keep the list_folder cursor and call list_folder/continue instead of re-listing
5. On a rate-limit error wait retry_after seconds; too_many_write_operations means write contention, so serialise writes