Add resproxy API support

Add lookupResproxy method to IPinfoWrapper for looking up residential proxy
information for IP addresses.

The resproxy API endpoint returns:
- ip: The IP address
- last_seen: Last recorded date when the proxy was active
- percent_days_seen: Percentage of days active in the last 7-day period
- service: Name of the residential proxy service

Author: silvanocerza

__tests__/fixtures/resproxy/175.107.211.204.json

@@ -0,0 +1,6 @@
+{
+    "ip": "175.107.211.204",
+    "last_seen": "2026-01-14",
+    "percent_days_seen": 50,
+    "service": "DataImpulse"
+}

__tests__/fixtures/resproxy/8.8.8.8.json

@@ -0,0 +1 @@
+{}

__tests__/ipinfoWrapper.test.ts

@@ -1,5 +1,5 @@
 import * as dotenv from "dotenv";
-import { AsnResponse, IPinfo } from "../src/common";
+import { AsnResponse, IPinfo, Resproxy } from "../src/common";
 import IPinfoWrapper from "../src/ipinfoWrapper";
 
 let ipinfoWrapper: IPinfoWrapper;
@@ -195,6 +195,24 @@ describe("IPinfoWrapper", () => {
         expect(data.bogon).toEqual(true);
     });
 
+    test("lookupResproxy", async () => {
+        // test multiple times for cache.
+        for (let i = 0; i < 5; i++) {
+            const data: Resproxy = await ipinfoWrapper.lookupResproxy(
+                "175.107.211.204"
+            );
+            expect(data.ip).toEqual("175.107.211.204");
+            expect(data.last_seen).toEqual("2026-01-14");
+            expect(data.percent_days_seen).toEqual(50);
+            expect(data.service).toEqual("DataImpulse");
+        }
+    });
+
+    test("lookupResproxyEmpty", async () => {
+        const data: Resproxy = await ipinfoWrapper.lookupResproxy("8.8.8.8");
+        expect(data).toEqual({});
+    });
+
     test("Error is thrown for invalid token", async () => {
         const ipinfo = new IPinfoWrapper("invalid-token");
         await expect(ipinfo.lookupIp("1.2.3.4")).rejects.toThrow();

__tests__/jest.setup.js

@@ -32,6 +32,22 @@ module.exports = async function globalSetup() {
                 method: "POST",
                 path: "/tools/map",
                 response: path.resolve(__dirname, "./fixtures/tools/map.json")
+            },
+            {
+                method: "GET",
+                path: "/resproxy/175.107.211.204",
+                response: path.resolve(
+                    __dirname,
+                    "./fixtures/resproxy/175.107.211.204.json"
+                )
+            },
+            {
+                method: "GET",
+                path: "/resproxy/8.8.8.8",
+                response: path.resolve(
+                    __dirname,
+                    "./fixtures/resproxy/8.8.8.8.json"
+                )
             }
         ]
     };

package-lock.json

@@ -2,6 +2,7 @@ export const HOST: string = "ipinfo.io";
 export const HOST_LITE: string = "api.ipinfo.io/lite";
 export const HOST_CORE: string = "api.ipinfo.io/lookup";
 export const HOST_PLUS: string = "api.ipinfo.io/lookup";
+export const HOST_RESPROXY: string = "ipinfo.io/resproxy";
 
 // cache version
 export const CACHE_VSN: string = "1";
@@ -244,6 +245,13 @@ export interface MapResponse {
     reportUrl: string;
 }
 
+export interface Resproxy {
+    ip: string;
+    last_seen: string;
+    percent_days_seen: number;
+    service: string;
+}
+
 export interface BatchResponse {
     [key: string]:
         | IPinfo

src/common.ts

@@ -31,7 +31,8 @@ export {
     Prefixes6,
     AsnResponse,
     MapResponse,
-    BatchResponse
+    BatchResponse,
+    Resproxy
 } from "./common";
 
 export default IPinfoWrapper;

src/index.ts

@@ -16,6 +16,7 @@ import {
     AsnResponse,
     MapResponse,
     BatchResponse,
+    Resproxy,
     BATCH_MAX_SIZE,
     BATCH_REQ_TIMEOUT_DEFAULT,
     REQUEST_TIMEOUT_DEFAULT,
@@ -215,6 +216,26 @@ export default class IPinfoWrapper {
         });
     }
 
+    /**
+     * Lookup residential proxy information using the IP.
+     *
+     * @param ip IP address to check for residential proxy information.
+     * @return Response containing Resproxy data if the IP is a residential proxy.
+     */
+    public async lookupResproxy(ip: string): Promise<Resproxy> {
+        const cacheKey = `resproxy:${ip}`;
+        const data = await this.cache.get(IPinfoWrapper.cacheKey(cacheKey));
+        if (data) {
+            return data;
+        }
+
+        return this.fetchApi(`resproxy/${ip}`).then(async (response) => {
+            const resproxy = (await response.json()) as Resproxy;
+            this.cache.set(IPinfoWrapper.cacheKey(cacheKey), resproxy);
+            return resproxy;
+        });
+    }
+
     /**
      * Get a mapping of a list of IPs on a world map.
      *