# IPv6 address classify

`ipv6-address-classify` · version 1.0.0 · URLs & IP addresses · free, no key needed

Classify an IPv6 address against the static IANA IPv6 special-purpose address registry.

**Use when you need to: ipv6 address classify · is ipv6 link local · ipv6 special purpose lookup.**

## Supported

- ipv6 address classify
- is ipv6 link local
- ipv6 special purpose lookup

## Not supported

- IPv4
- routing-table-aware or organization-specific reservations
- live registry lookups

## Behavior

- address accepts any RFC 4291 textual form (see ipv6-parse).
- classification is the single most-specific (longest-prefix) matching label from a fixed, embedded table of well-known IANA IPv6 special-purpose ranges; "global_unicast" if no entry matches.
- Labels: unspecified (::/128), loopback (::1/128), ipv4_mapped (::ffff:0:0/96), ipv4_ipv6_translation (64:ff9b::/96, NAT64 well-known prefix), documentation (2001:db8::/32), unique_local (fc00::/7), link_local (fe80::/10), multicast (ff00::/8), global_unicast (everything else).
- matched_range is the exact embedded CIDR entry that matched, or null when classification is "global_unicast".

## Input

- `address` (string, required): max length 45

## Output

- `classification` (one of "unspecified", "loopback", "ipv4_mapped", "ipv4_ipv6_translation", "documentation", "unique_local", "link_local", "multicast", "global_unicast", required)
- `matched_range` (string or null, required): max length 49

## Limits

- max address length: 45

## Example

Request input:

```json
{
  "address": "fe80::1"
}
```

Response:

```json
{
  "result": {
    "classification": "link_local",
    "matched_range": "fe80::/10"
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "ipv6-address-classify",
  "version": "1.0.0",
  "input": {
    "address": "fe80::1"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/ipv6-address-classify/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"address":"fe80::1"}'
```

The machine-readable contract is at [/v1/tools/ipv6-address-classify/versions/1.0.0](/v1/tools/ipv6-address-classify/versions/1.0.0).

### CLI

```sh
node cli.mjs run ipv6-address-classify 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [IPv4 address classify](/tools/ipv4-address-classify): Classify an IPv4 address against the static IANA IPv4 special-purpose address registry.
- [IPv6 address compare](/tools/ipv6-address-compare): Compare two IPv6 addresses by their numeric 128-bit value.
- [IPv6 address distance](/tools/ipv6-address-distance): Compute the signed integer distance between two IPv6 addresses (address_b minus address_a).
- [IPv6 address offset](/tools/ipv6-address-offset): Add a signed integer offset to an IPv6 address, throwing if the result leaves the IPv6 address space.
- [IPv6 in CIDR](/tools/ipv6-in-cidr): Test whether an IPv6 address lies in a CIDR prefix whose host bits are zero.
- [IPv6 normalize](/tools/ipv6-normalize): Normalize any valid textual IPv6 address directly into its RFC 5952 canonical compressed string.