# IPv6 IPv4 mapped

`ipv6-ipv4-mapped` · version 1.0.0 · URLs & IP addresses · free, no key needed

Convert between an IPv4 address and its IPv4-mapped IPv6 form (::ffff:0:0/96), in either direction.

**Use when you need to: ipv6 ipv4 mapped · ipv4 to mapped ipv6 · extract ipv4 from mapped ipv6.**

## Supported

- ipv6 ipv4 mapped
- ipv4 to mapped ipv6
- extract ipv4 from mapped ipv6

## Not supported

- IPv4-compatible (deprecated, ::a.b.c.d) form
- NAT64 (64:ff9b::/96) embedding

## Behavior

- Input is exactly one of ipv4 or address; unknown fields, both, or neither throw.
- ipv4 is a canonical dotted-decimal IPv4 address; the tool returns address, its IPv4-mapped IPv6 form ::ffff:a.b.c.d in RFC 5952 canonical (lowercase hex, e.g. ::ffff:c0a8:101) form.
- address accepts any RFC 4291 textual form; the tool returns ipv4, the embedded IPv4 address, only if address lies in ::ffff:0:0/96 — otherwise it throws "address is not an IPv4-mapped IPv6 address".

## Input

- object

## Output

- object

## Limits

- max address length: 45

## Example

Request input:

```json
{
  "ipv4": "192.168.1.1"
}
```

Response:

```json
{
  "result": {
    "address": "::ffff:c0a8:101"
  }
}
```

## How to call it

### MCP

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

```json
{
  "id": "ipv6-ipv4-mapped",
  "version": "1.0.0",
  "input": {
    "ipv4": "192.168.1.1"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/ipv6-ipv4-mapped/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"ipv4":"192.168.1.1"}'
```

The machine-readable contract is at [/v1/tools/ipv6-ipv4-mapped/versions/1.0.0](/v1/tools/ipv6-ipv4-mapped/versions/1.0.0).

### CLI

```sh
node cli.mjs run ipv6-ipv4-mapped 1.0.0 --input input.json --base-url https://computefirst.net
```

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

## Related tools

- [IPv4 address offset](/tools/ipv4-address-offset): Add a signed integer offset to an IPv4 address, throwing if the result leaves the IPv4 address space.
- [IPv4 CIDR parse](/tools/ipv4-cidr-parse): Parse an IPv4 CIDR block into its network, broadcast, netmask, wildcard mask, usable host range and address counts.
- [IPv4 format](/tools/ipv4-format): Format a uint32 integer string or four octets as a canonical dotted-decimal IPv4 address.
- [IPv4 mask convert](/tools/ipv4-mask-convert): Convert between an IPv4 prefix length, dotted subnet netmask, and dotted wildcard (host) mask.
- [IPv4 parse](/tools/ipv4-parse): Parse a canonical dotted-decimal IPv4 address into octets and a uint32 integer string.
- [IPv4 range to cidrs](/tools/ipv4-range-to-cidrs): Convert an arbitrary IPv4 address range into the minimal list of CIDR blocks that exactly covers it.