IP Address List Comparator

Paste or upload your first IP list into List A and the second into List B. Select a comparison mode (Exact Match for direct IP comparison, CIDR Range Matching to check if IPs fall within subnets, or Mixed Mode for both simultaneously). Click Compare and review the results in organized tabs: Exact Matches, Subnet Matches, Unique to List A, Unique to List B, and Invalid Entries. You can export any result set as CSV, TXT, or JSON.

Yes. Select CIDR Range Matching or Mixed Mode. The tool will check every IP address against every CIDR block and show you which IPs fall within which subnets. For example, 192.168.1.25 will correctly match 192.168.1.0/24, and 10.0.0.5 will match 10.0.0.0/8. The subnet match results include the matching CIDR, network address, and subnet mask for full transparency.

Yes. The IP Address List Comparator fully supports IPv6 addresses and IPv6 CIDR blocks (e.g., 2001:db8::/48, 2001:db8::1). IPv6 addresses are converted to BigInt (128-bit) representation for precise numeric comparison. IPv6 CIDR blocks are handled with the same mathematical rigor as IPv4 — network addresses, broadcast addresses, and range inclusion are all computed correctly using 128-bit arithmetic.

No. Absolutely not. Every comparison, validation, and computation happens entirely inside your browser using JavaScript. No data is ever sent to any server, API, or third-party service. There are no network requests, no background uploads, and no data logging. This makes the tool suitable for comparing highly sensitive infrastructure data including firewall rules, security group configurations, and access control lists.

The tool is designed for enterprise-scale datasets. For datasets under 25,000 rows, processing happens instantly on the main thread. For larger datasets (up to millions of entries), processing automatically offloads to a Web Worker, keeping your browser fully responsive. The optimized integer-based comparison algorithm achieves O(N log N) complexity, making it feasible to compare 100,000+ entries in seconds. The practical limit depends on your device's available memory.

The tool supports IPv4 addresses (192.168.1.1), IPv6 addresses (2001:db8::1), IPv4 CIDR blocks (10.0.0.0/8), IPv6 CIDR blocks (2001:db8::/48), and mixed lists containing any combination of these. TXT, CSV, and LOG file formats are supported for upload. Entries can be comma-separated, newline-separated, or mixed. The validation engine normalizes and categorizes every entry before comparison.

CIDR subnet matching uses integer-based range comparison. For IPv4 CIDR blocks, each IP is converted to a 32-bit unsigned integer and checked against the CIDR's network address range (network address to broadcast address). For IPv6 CIDR blocks, the same logic applies using JavaScript BigInt for 128-bit arithmetic. This mathematical approach is exact — there is no string matching, no approximation, and no ambiguity. The CIDR is fully expanded to its network address, subnet mask, and address range for verification.

Exact Match compares IP addresses directly — 192.168.1.1 only matches 192.168.1.1. CIDR Range Matching checks whether an IP address falls within a subnet range — 192.168.1.25 would match 192.168.1.0/24 even though it is not the exact network address. Mixed Mode combines both: IPs can match by exact equality or by falling within a CIDR range. Use Exact Match for strict IP-to-IP comparison, CIDR mode for subnet membership checks, and Mixed Mode for comprehensive firewall and security group audits.

Yes. CIDR-to-CIDR comparison is supported in all modes. The tool can check whether two CIDR blocks overlap, whether one is a subset of another, or whether they are identical. For example, 10.0.0.0/16 and 10.0.1.0/24 would be flagged as overlapping, while 192.168.1.0/24 and 10.0.0.0/8 would show no overlap.

Every entry is validated before comparison. The engine categorizes each entry as Valid IPv4, Valid IPv6, Valid CIDR (v4 or v6), or Invalid. Invalid entries are highlighted in red with descriptive error messages (e.g., 'Invalid octet: 256', 'Malformed CIDR prefix: /35', 'Incomplete IPv6'). The validation never stops processing, and invalid entries are excluded from comparison results but preserved in the Invalid Entries tab for review.

Yes. You can export any result tab individually (Exact Matches, Subnet Matches, Unique A, Unique B, or Invalid Entries) as CSV, TXT, or JSON. You can also export a Full Report containing all results in a single file. All exports are generated client-side with no server interaction. Use the Copy button to copy results directly to your clipboard.

Yes. The IP Address List Comparator meets the requirements of SOC analysts, incident responders, and threat intelligence teams. Key features for security operations include: support for threat intelligence IP feeds, firewall blocklist comparison, access log analysis, exact and subnet matching for IoC validation, enterprise-grade privacy (no data leaves the browser), large dataset support for million-line log files, and comprehensive export capabilities for report generation.