Amazon S3 vs OneDrive and SharePoint files (Microsoft Graph)

Amazon S3

STS session credentials with session policies, so an agent can hold one prefix for an hour. Egress to the internet is billed per GB after 100 GB a month.

OneDrive and SharePoint files (Microsoft Graph)

One REST surface covers personal OneDrive, work OneDrive and SharePoint libraries, with resumable uploads, sharing links that take an expiry date and per-file Selected permissions. The status page needs JavaScript, an app must be registered and consented to by a person, and the JavaScript client on npm lacks a token-leak fix merged in June 2026.

Amazon S3

1. Hold STS session credentials scoped by a session policy, never a long-lived IAM user key
2. Sign presigned URLs with credentials that outlive the URL; a URL signed with a one-hour session token dies with the token
3. Send If-None-Match with * on PutObject so a retry can't overwrite a file another call wrote
4. Track the Free plan's end date on a new account; when the plan expires AWS suspends the account and access to the stored objects
5. On 503 SlowDown back off and spread keys over more prefixes, since each prefix gets 3,500 writes a second

OneDrive and SharePoint files (Microsoft Graph)

1. Use PUT /content only up to 250 MB. Above 10 MiB Microsoft advises createUploadSession, with fragments in multiples of 320 KiB and under 60 MiB each
2. Send the bearer token on the createUploadSession POST only. The PUT calls to uploadUrl can return 401 if an Authorization header is included
3. Set expirationDateTime and scope on createLink. Without a scope the tenant's default link type is created, which may be wider than intended
4. Follow the 302 from GET /content straight away. Pre-authenticated download URLs can expire within minutes and need no Authorization header
5. Wait for Retry-After on 429 and 503. Throttled requests still count against the limits, and continued overuse can get the app blocked