Unix and Networking Tools
Chmod Calculator
The Chmod Calculator lets you click to toggle read, write and execute permissions for owner, group and other. The octal code (755, 644 etc.) updates instantly along with the symbolic notation (rwxr-xr-x) and the exact chmod command to run.
Eight presets cover the most common permission patterns:
| Code | Use Case |
|---|---|
| 755 | Executable scripts |
| 644 | Regular files |
| 600 | Private SSH keys |
| 700 | Private scripts |
| 777 | World-writable (⚠️ avoid in production) |
The binary grid shows the bit-level representation of each permission set — useful for teaching or understanding exactly why chmod 4+6+1=7 means full access.
DNS Lookup
The DNS Lookup queries Cloudflare's public DNS for A, AAAA, MX, TXT, NS, CNAME and SOA records for any domain. Select which record types to query, enter a domain and see all results with TTL values in under a second.
Useful for verifying DNS propagation after a domain migration, checking SPF and DMARC TXT records for email deliverability, and confirming that NS records point to the right nameservers.