IPv6 Utility JSON API Guide

This API allows you to programmatically interact with the IPv6 subnetting and conversion tools.

📍 Base URL

http://tools.forwardingplane.net/api/

📘 Endpoints

/api/subnets

Generate or count subnets from a given IPv6 prefix.

• prefix — IPv6 CIDR (e.g. 3ffe::/32)
• new_prefix — New prefix length (e.g. 40)
• limit — (optional) Limit the number of subnets returned
• count_only — (optional) Set to true to return only the count

GET /api/subnets?prefix=3ffe::/32&new_prefix=40&limit=5

{
  "count": 256,
  "subnets": [
    "3ffe::/40",
    "3ffe:0:100::/40",
    "3ffe:0:200::/40",
    ...
  ]
}

/api/convert

Convert between IPv4 and synthesized IPv6 (RFC 6052).

• ip — IPv4 or synthesized IPv6 address
• prefix — (optional) IPv6 prefix for IPv4 to IPv6 conversion (default: 64:ff9b::)

GET /api/convert?ip=192.0.2.33&prefix=64:ff9b::

{
  "result": "64:ff9b::c000:221"
}

/api/decode

Decode a MAC address from an SLAAC IPv6 address (EUI-64 format).

• ipv6 — SLAAC IPv6 address (e.g. 2001:db8::0200:ff:fe00:1234)

GET /api/decode?ipv6=2001:db8::0200:ff:fe00:1234

{
  "mac": "00:00:00:00:12:34"
}

/api/linklocal

Convert a link-local IPv6 address to a MAC address, or a MAC address to a link-local address.

• value — Either a MAC address (e.g. 00:1a:2b:3c:4d:5e) or a link-local IPv6 address (e.g. fe80::1a2b:3cff:fe4d:5e6f)

GET /api/linklocal?value=00:1a:2b:3c:4d:5e

GET /api/linklocal?value=fe80::1a2b:3cff:fe4d:5e6f

{
  "result": "00:1a:2b:3c:4d:5e"
}

🛠 Notes

• All endpoints respond with JSON
• Make sure your client supports IPv6 loopback [::1] or adapt the server to use localhost
• For large subnet generations, use the limit parameter to avoid long responses

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