---
title: "Lookup any AS Number and receive its details"
method: GET
path: "/lookup/asn/{asn}"
tags: ["Lookup"]
---

# Lookup any AS Number and receive its details

`GET /lookup/asn/{asn}`

## Request

- Base URL: `https://v2.greipapi.com`
- URL: `https://v2.greipapi.com/lookup/asn/{asn}`
- Auth: HTTP bearer

This API method allows you to look up any given Autonomous System Number (ASN) and retrieve comprehensive data associated with it.

The information returned includes the ASN name, organization name, country, associated domain, contact email, phone number, total IPs, and a detailed list of all related routes (both IPv4 and IPv6). This functionality is essential for network analysis, troubleshooting, and understanding the infrastructure behind IP addresses.

## Path parameters

- `asn` string, required

## Query parameters

- `format` string
- `mode` string
- `source` string
- `user_id` string

## Response `200`

OK

- GreipJsonSuccessEnvelope
  - `success` boolean, required
  - `data` object, required: Endpoint-specific payload.
  - `execution_ms` integer, required

## Changes

- **2026-11-03** `5ef5b288383a`: 2 info
  - api tag `Lookup` added
  - added the media type `application/json` for the response with the status `200`
- **2026-10-19** `9346ce4dfd7c`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/greip/apis/greip-api/changes/lookup/asn/:asn/get.md)

---

[API](https://skmtc.dev/greip/apis/greip-api.md) - [All operations](https://skmtc.dev/greip/apis/greip-api/llms.txt) - [OpenAPI document](https://skmtc.dev/greip/apis/greip-api/revisions/5ef5b288383a?raw)