Find the files that will fail before you move a folder to OneDrive or SharePoint.
Pick a folder and see every file and folder that Microsoft will reject: invalid characters, reserved names, paths that are too long and names that clash. Each one comes with a suggested new name. It runs in your browser on Mac or Windows. Nothing is uploaded.
- No install, no admin rights
- No Microsoft sign-in
- Mac and Windows
- File contents are never opened
Made for the person doing the move
Moving a shared folder
From a file server, NAS, external drive, Dropbox or Google Drive into SharePoint or a team's OneDrive.
Working on a Mac
macOS allows names like Q&A: plans? or Draft* that OneDrive refuses. Microsoft's migration tools are Windows-only.
Not the tenant admin
You don't need access to the Microsoft 365 admin center or permission to install software. Just a browser.
Check a folder
Only names, folder structure and file sizes are read, inside this browser tab. File contents are never opened and nothing is sent to a server. How we know
Drag a folder here or
Works in Chrome, Edge, Firefox and Safari on a computer. Phones and tablets can't select folders.
Destination details (optional, for path-length checks)
Paste the SharePoint or OneDrive folder URL. It is only used to count characters. The 400-character limit counts everything after sharepoint.com/.
Optional. Flags files that Excel (218) or Word and File Explorer (259) can't open after sync.
Already bought a licence?
Paste your licence key to unlock the full report in this browser.
What it checks
Rules follow Microsoft's published OneDrive and SharePoint restrictions and path length limits. Rules last reviewed 28 September 2026.
| Check | Level | Example |
|---|---|---|
Invalid characters " * : < > ? \ | | Blocker | Q&A: budget?.xlsx |
| Names that start or end with a space | Blocker | Invoices / |
Reserved names: CON, PRN, AUX, NUL, COM0–9, LPT0–9, .lock, desktop.ini | Blocker | AUX/ |
_vti_ anywhere in a name, names starting with ~$ | Blocker | ~$Budget.xlsx |
| Hidden control characters (common on Mac, e.g. folder-icon files) | Blocker | Icon⏎ |
| Two names in one folder that differ only by case | Blocker | Report.pdf + report.pdf |
| Full cloud path over 400 characters | Blocker | deeply nested project folders |
| Files over 250 GB | Blocker | VM disk images |
| Synced Windows path over 259 (218 for Excel) | Warning | opens fine online, fails in desktop Excel |
Device name with an extension, e.g. aux.txt; names ending with a period; forms at the library root; leftover lock/temp files | Warning | Final. |
Not covered: permissions, version history, file contents, file types blocked by your organisation's policy, and item-count limits of the sync app. A clean result does not guarantee a migration will succeed.
Do you need this? An honest comparison
| Runs on | Needs | Cost | |
|---|---|---|---|
| Local Preflight | Any desktop browser (Mac, Windows, Linux) | Nothing | Free summary, €12 once for the full list |
| SharePoint Migration Tool (scan-only mode) | Windows | Install, Microsoft 365 sign-in with access to the destination | Free |
| Microsoft FastTrack Preflight-OneDrive script | Windows PowerShell | Comfort with PowerShell and extra modules; last updated 2019 | Free |
| Just upload and fix errors afterwards | — | Time: failed items are reported one by one, often after hours of syncing | Free |
If you are a Windows admin already running the SharePoint Migration Tool, you probably don't need Local Preflight. It is for everyone else who needs a clear fix list before the move.
Pricing
Free check
€0
- Scan any folder, any size
- Totals for every type of problem
- The first 10 problems with suggested fixes
Full report licence
€12 one-time, incl. VAT where applicable
- Every problem with its exact path and suggested new name
- CSV export to work through in Excel
- Unlimited scans, rule updates included
- Licence key to use on your other computers
No subscription. Paddle.com is the seller of record and handles payment, VAT and invoices. 14-day refund if it doesn't work for you.
Questions
Are my files uploaded?
No. The check runs as JavaScript in this tab. It reads names, folder structure and sizes, never file contents, and makes no network request with them. You can verify this: open the browser's developer tools (Network tab) while scanning, or disconnect from the internet after the page has loaded. The scan still works. Usage statistics record counts only (for example "a scan found between 11 and 100 problems"), never names or paths.
Chrome says "Upload files to this site?". Why?
That is Chrome's standard wording for the older folder picker. Nothing is uploaded. In Chrome and Edge the "Choose a folder" button uses the newer picker that asks to view files instead, and drag and drop avoids the prompt in every browser.
Does it rename or change anything?
No. Access is read-only. You get a list of what to rename and a suggested new name for each item. You make the changes yourself.
How big a folder can it handle?
Hundreds of thousands of files. 200,000 paths are checked in well under a second once the browser has listed them. Listing a large folder on a network drive can take a few minutes.
I paid but closed the page before seeing my key.
Reopen this page in the same browser; it picks up the purchase automatically. Otherwise contact support with the email you used at checkout.