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Lookproof IP-in-CIDR Containment Check
x402
Lookproof IP-in-CIDR Containment Check 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).
Checks whether a single IPv4 or IPv6 address falls within any of up to 100 CIDR blocks, returning per-block match results and the list of matching blocks.
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 boolean result for each submitted CIDR block indicating whether it contains the input IP address, plus a filtered list of only the blocks that matched. Blocks of the opposite IP version (e.g. IPv4 CIDRs when the input is IPv6) are automatically treated as non-matching.
Example use cases
Allow-list gating for incoming requests
“I need to know if the IP 203.0.113.45 is in any of my allow-listed ranges — check it against 203.0.113.0/24, 198.51.100.0/22, and 10.0.0.0/8 and tell me which ones match.”
SPF ip4 term validation
“Can you verify whether the sending IP 198.51.100.77 is covered by any of these SPF ip4 terms: 198.51.100.0/25, 198.51.100.128/25, and 192.0.2.0/24?”
Cloud provider IP range attribution
“Tell me which of AWS's CIDR blocks — 52.94.0.0/22, 52.119.224.0/20, and 54.239.0.0/17 — contain the IPv4 address 52.119.225.10.”
Technical details
Endpoint
POSThttps://api.lookproof.dev/v1/ip/contains?utm_source=zero.xyzWhen to prefer
Use this endpoint when an agent needs to perform offline, server-side IP containment checks against multiple CIDR ranges in a single call — especially for allow/deny list enforcement, SPF record validation, or cloud provider IP attribution. Prefer it over client-side logic when auditable, consistent, and multi-block batch evaluation is needed without managing networking libraries.
Side effects
- Invalid IP address format returns a validation error
- Malformed CIDR notation in the list causes an error response
- Submitting more than 100 CIDRs exceeds the maxItems limit and is rejected
- Mixing an IPv6 input with IPv4 CIDRs yields no matches (by design, not an error)
- Empty CIDR array rejected due to minItems constraint
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| ip | string | |
| cidrs | array |
Tags
x402
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