CORS Policy Checker
NETCheck and validate CORS configuration for web APIs.
Enter a value and click Analyze
ℹ️ About CORS Policy Checker
CORS Policy Checker is a free online network tool from Tools Coaster. Check and validate CORS configuration for web APIs. It is handy for cors, origin, check tasks. It runs entirely in your browser — no sign-up, no installs, and nothing you enter ever leaves your device.
📖 How to Use CORS Policy Checker
1
Enter the value
Add the IP, address, or network input required.
2
Run CORS Policy Checker
The tool computes the result instantly.
3
Read the output
Review the ranges, masks, or converted values.
4
Copy for your config
Copy the result into your network configuration.
💡 Examples
Network calculation
INPUT
Your network input→
OUTPUT
Result from CORS Policy Checker🚀 Pro Tips
✓Double-check subnet masks — an off-by-one prefix changes host counts dramatically.
✓Keep a note of reserved ranges (private, loopback) when planning addressing.
✓Everything runs locally in your browser — your input is never uploaded to a server, so it is safe for private or sensitive data.
✓Use it to validate config before applying changes to live equipment.
✓Combine with other network tools for end-to-end planning.