Paste filenames and instantly see which ones break on Windows, SharePoint, Google Drive, Dropbox, and more
- Paste or type filenames, one per line
- Toggle target platforms: Windows, macOS, SharePoint, Google Drive, Dropbox, S3
- See issues highlighted by platform with one-click fixes
Proof: Used by IT teams during cloud migrations to validate thousands of filenames at once
Check filenames against platform-specific rules in seconds. Catch issues before they block uploads, break sync, or corrupt paths.
- Detects invalid characters, reserved names, path length violations, and trailing spaces/periods for each platform.
- Highlights issues by severity and platform so you know exactly what to fix and why.
- Generates corrected filenames you can copy or hand to Renamed.to for bulk automation.
100% browser-side. Your filenames never leave your machine.
Every platform has different filename rules. SharePoint blocks tildes and #. Windows reserves CON and NUL. S3 allows almost anything but penalizes non-ASCII. This tool checks them all at once so nothing breaks when you migrate, sync, or share.
Free, no signup, and 100% browser-side until you connect Renamed.to for automation.
Compatibility checker
Paste filenames below and toggle platforms to check. Issues are highlighted inline with suggested fixes you can copy.
Paste filenames above to check compatibility
One filename per line. Checks against 7 platforms and cloud services.
How filename compatibility checking works
1. Paste filenames in bulk
Paste filenames from a spreadsheet, terminal output, or file listing. The checker accepts one filename per line and can handle hundreds at once. No file uploads needed—just the names.
2. Platform rules applied instantly
Each filename is tested against the rules of every enabled platform. Windows checks for reserved names and invalid characters. SharePoint checks path length and special sequences. Dropbox flags leading/trailing whitespace. S3 warns about non-ASCII characters that cause encoding issues.
3. Fix issues or automate with Renamed.to
Copy the suggested fixes and rename files manually, or connect Renamed.to to automatically fix filenames across Google Drive, Dropbox, and local folders. The AI reads your files and applies platform-safe names in bulk.
Platform filename restrictions at a glance
Every cloud platform and operating system enforces its own filename rules. Here are the key restrictions this tool checks for each platform.
Windows
- No
< > : " / \ | ? *characters - No trailing spaces or periods
- Reserved names: CON, PRN, AUX, NUL, COM1-9, LPT1-9
- Max path length: 260 characters (default)
macOS
- No
:or/characters - No filenames starting with a dot (hidden files)
- Max filename length: 255 characters
- Case-insensitive by default (HFS+)
SharePoint / OneDrive
- No
" * : < > ? / \ |characters - No # % ~ or consecutive periods (..)
- No _vti_ prefix or .lock extension
- Max full path: 400 characters
Google Drive
- No
/or\characters - Max filename length: 255 characters
- No leading or trailing spaces
- Allows most special characters
Dropbox
- No
/or\characters - No trailing spaces or periods
- Max full path: 260 characters
- Case-insensitive conflict detection
Amazon S3
- Max key length: 1,024 bytes (UTF-8)
- Non-ASCII characters require URL encoding
- Avoid &, $, @, =, +, and whitespace
- No leading ./ or ../ path traversal
Migrating to the cloud? Renamed.to fixes filenames automatically.
You found the issues. Now fix them in bulk. Renamed.to scans your files, detects platform-incompatible names, and renames them to safe versions automatically. Works with Google Drive, Dropbox, SharePoint, and local folders.
50 free renames, no credit card required.
Frequently asked questions
What characters are not allowed in Windows filenames?
Windows does not allow the characters < > : " / \ | ? * in filenames. Filenames cannot end with a space or period. System-reserved names like CON, PRN, AUX, NUL, COM1 through COM9, and LPT1 through LPT9 are also blocked regardless of file extension.
What are the SharePoint filename restrictions?
SharePoint and OneDrive block the characters " * : < > ? / \ | as well as # % ~ and consecutive periods (..). Filenames cannot start or end with a space or end with a period. The full path including the filename must stay under 400 characters. Names containing _vti_ or ending in .lock are also restricted.
Can I check filenames for multiple platforms at once?
Yes. Toggle on any combination of the six supported platforms—Windows, macOS, SharePoint, Google Drive, Dropbox, and S3—to check all of them simultaneously. Issues are labeled by platform so you can see exactly which system each problem affects.
Does this tool upload my filenames anywhere?
No. The compatibility checker runs entirely in your browser using JavaScript. Your filenames are never sent to a server, stored, or logged. This makes it safe for checking sensitive or confidential filenames during migrations.
How do I fix filenames that fail compatibility checks?
The tool suggests a corrected version for each failing filename that resolves all detected issues. You can copy the fixed names and rename files manually, or use Renamed.to to automatically fix and rename files in bulk across Google Drive, Dropbox, and local folders.
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