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Network / Address planning

IP Range Overlap Checker

Check IPv4 ranges before adding a VPN, office, or cloud network. Compare two lists locally and export overlapping pairs for review.

Runs entirely on your deviceNo uploads, accounts, cookies, or personal tracking.

Compare network ranges

Existing networks against planned additions

One IPv4 CIDR, single IP, or start-end range per line. Add an optional name before the address, separated by a space or tab. Up to 500 entries and 256 KiB per list.

Example: Head office 10.0.0.0/16

Example: VPN 10.0.10.1-10.0.10.100

Only ranges across the two lists are compared. Network and broadcast addresses are included. Overlap may be intentional; this checks address ranges, not connectivity or routing.

Paste both lists, then check for overlaps.
    1. Add your data

    Paste existing and planned IPv4 networks, one entry per line.

    2. Choose the result

    Check for exact matches, containment, and partial overlaps.

    3. Save it locally

    Review the ranges and download every overlapping pair as CSV.

    Practical guide

    Check address overlaps before connecting networks

    Compare your existing IPv4 networks with planned VPN, branch, or cloud ranges. All input stays in this browser tab, and the downloaded HTML works offline.

    Common uses

    • Review an office or cloud network before connecting it to your existing network.
    • Check a proposed VPN address pool against deployed subnets.
    • Export overlapping pairs for a network design review.

    What to expect

    Input formats
    Paste one CIDR, single IPv4 address, or start-end range per line. An optional name comes first, separated by spaces or a tab. Each list supports 500 entries and 256 KiB. IPv6 and file import are not supported.
    Worked example
    Existing: Head office 10.0.0.0/16. Planned: VPN 10.0.10.0/24. The existing network contains the planned network; the overlap is 10.0.10.0–10.0.10.255.
    CIDR boundaries
    10.0.10.34/24 is checked as 10.0.10.0/24, with an explicit notice. A single IP is checked as /32. Leading-zero octets are rejected to avoid ambiguous notation.
    Review and export
    Results distinguish exact matches, directional containment, and partial overlap. Review 50 pairs per page; CSV includes every pair, with original line numbers and formula-safe names.
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