Calculate IPv6 subnet boundaries, first/last addresses, and host counts.
Execution runs 100% locally inside the browser sandbox using HTML5 Canvas, Web Cryptography Subtle API, and Web Workers. Zero egress.
Zero network latency. Operates completely offline with zero dependencies on third-party backend servers or cloud services.
Built according to official RFC specifications, cryptographic test vectors, and enterprise-grade data transformation standards.
Type an IPv6 prefix like 2001:db8:abcd::/64.
Review first address, last address, and total address space.
Copy network address details for cloud routing tables.
A single /64 subnet contains 2^64 addresses (approximately 18.4 quintillion IPs).
/48 is the standard prefix assigned by ISPs and RIRs to end-user sites and corporate networks.
Zero-egress companion tools in the Security & Network suite
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Measure cryptographic randomness, Shannon entropy (0-8 bits/byte), Chi-square test, and byte distributions.
Generate secure RFC 6238 Base32 TOTP secret keys and standard otpauth:// URIs for Google Authenticator.
Construct and validate HTTP CSP headers and meta tags.
