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Lookproof CIDR Block Calculator
x402
Lookproof CIDR Block Calculator is a paid API for AI agents from api.lookproof.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-31).
Computes full CIDR block details (network address, first/last host, address count, netmask, host mask, and host-bits-set flag) for any IPv4 or IPv6 CIDR notation input, entirely offline.
Price / call$0.002
Success—
StatusUnknown
How this service works
Check SPF, DMARC, DKIM, MTA-STS, DNSSEC and more, with results that explain what was found and why. Free browser checks and a pay-per-request API with x402.
Output
Returns a structured object containing: the canonical network address, the first and last address in the block, total number of addresses, the netmask (e.g. 255.255.255.0), the host mask (wildcard mask), and a boolean flag indicating whether the input CIDR had host bits set beyond the prefix. Works for both IPv4 and IPv6. Computation is done offline with no external DNS or registry lookups.
Example use cases
Firewall rule subnet verification
“I'm writing a firewall rule and need to confirm the exact network address, broadcast address, and number of hosts covered by 10.20.30.0/22 — can you compute the full CIDR breakdown?”
SPF record CIDR range explanation
“Our SPF record includes the range 203.0.113.64/26 and I need to explain to the team exactly which IPs that covers — give me the first address, last address, and total count.”
Cloud VPC subnet planning
“I'm planning a VPC and want to know if 172.31.0.0/20 has any host bits set and how many usable addresses it gives me, including the netmask and host mask.”
Technical details
Endpoint
GEThttps://api.lookproof.dev/v1/ip/cidr?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need authoritative, offline computation of CIDR block properties — particularly for firewall rule validation, SPF record IP range explanation, cloud subnet planning, or any scenario where you must confirm network/broadcast addresses, address counts, or netmasks without relying on external registry data. It handles both IPv4 and IPv6, making it suitable for modern dual-stack environments.
Side effects
- Invalid CIDR notation (e.g. missing prefix length or malformed IP) returns a 4xx error
- Prefix length out of range for address family (e.g. /33 for IPv4) returns a validation error
- Missing required 'cidr' query parameter returns a 400 bad request
- Extremely large IPv6 ranges may return address counts as big integers depending on response format
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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