diff --git a/packages/ui/certd-server/src/modules/cert/service/rdap-ss-client.ts b/packages/ui/certd-server/src/modules/cert/service/rdap-ss-client.ts
new file mode 100644
index 000000000..292a1d51c
--- /dev/null
+++ b/packages/ui/certd-server/src/modules/cert/service/rdap-ss-client.ts
@@ -0,0 +1,115 @@
+import { http, logger } from "@certd/basic";
+import dayjs from "dayjs";
+import customParseFormat from "dayjs/plugin/customParseFormat.js";
+
+import type { DomainInfo } from "./tld-client.js";
+
+dayjs.extend(customParseFormat);
+
+export class RdapSsClient {
+  private static readonly API = "https://rdap.ss/api/query";
+  private static readonly RATE_LIMITS = [
+    { windowMs: 60 * 1000, max: 30 },
+    { windowMs: 60 * 60 * 1000, max: 1200 },
+    { windowMs: 24 * 60 * 60 * 1000, max: 12000 },
+  ];
+  private static readonly MAX_WAIT_MS = 3 * 60 * 1000;
+  private static readonly DATA_RETENTION_MS = 24 * 60 * 60 * 1000;
+  private static requestTimes: number[] = [];
+
+  async getDomainInfo(domain: string): Promise<DomainInfo> {
+    await this.waitRateLimit();
+
+    const result = await http.request({
+      url: `${RdapSsClient.API}?q=${encodeURIComponent(domain)}`,
+      method: "GET",
+      logRes: false,
+    });
+
+    if (!result?.success || !result?.data) {
+      throw new Error(`【${domain}】rdap.ss查询失败`);
+    }
+
+    const data = result.data?.whoisData || result.data?.rawData || {};
+    const res: DomainInfo = {};
+    const expirationDate = this.parseFirstDate(data, ["Expiry Date", "Expiration Date", "Registry Expiry Date", "expires"]);
+    const registrationDate = this.parseFirstDate(data, ["Domain Name Commencement Date", "Created Date", "Creation Date", "Registration Date", "Registered On"]);
+
+    if (expirationDate) {
+      res.expirationDate = expirationDate;
+    }
+    if (registrationDate) {
+      res.registrationDate = registrationDate;
+    }
+
+    if (!res.expirationDate) {
+      throw new Error(`【${domain}】rdap.ss查询未找到过期时间`);
+    }
+
+    return res;
+  }
+
+  private async waitRateLimit() {
+    while (true) {
+      const now = Date.now();
+      RdapSsClient.requestTimes = RdapSsClient.requestTimes.filter(time => now - time < RdapSsClient.DATA_RETENTION_MS);
+
+      const waitMs = RdapSsClient.RATE_LIMITS.reduce((maxWaitMs, limit) => {
+        const times = RdapSsClient.requestTimes.filter(time => now - time < limit.windowMs);
+        if (times.length < limit.max) {
+          return maxWaitMs;
+        }
+        const earliestTime = Math.min(...times);
+        return Math.max(maxWaitMs, earliestTime + limit.windowMs - now);
+      }, 0);
+
+      if (waitMs <= 0) {
+        RdapSsClient.requestTimes.push(now);
+        return;
+      }
+
+      if (waitMs > RdapSsClient.MAX_WAIT_MS) {
+        throw new Error(`rdap.ss查询达到速率限制，等待时间超过3分钟`);
+      }
+
+      logger.warn(`rdap.ss查询达到速率限制，将在${waitMs}ms后重试`);
+      await this.sleep(waitMs);
+    }
+  }
+
+  private parseFirstDate(data: Record<string, any>, keys: string[]) {
+    for (const key of keys) {
+      const value = data[key];
+      const values = Array.isArray(value) ? value : [value];
+      for (const item of values) {
+        const timestamp = this.parseDateValue(item);
+        if (timestamp) {
+          return timestamp;
+        }
+      }
+    }
+  }
+
+  private parseDateValue(value: any) {
+    if (!value || typeof value !== "string") {
+      return;
+    }
+
+    const formats = ["DD-MM-YYYY", "YYYY-MM-DD", "YYYY-MM-DD HH:mm:ss", "YYYY/MM/DD", "YYYY/MM/DD HH:mm:ss", "MMM D YYYY", "MMM D, YYYY"];
+    for (const format of formats) {
+      const parsed = dayjs(value, format, true);
+      if (parsed.isValid()) {
+        return parsed.valueOf();
+      }
+    }
+
+    const parsed = dayjs(value);
+    if (parsed.isValid()) {
+      return parsed.valueOf();
+    }
+  }
+
+  private sleep(ms: number) {
+    return new Promise(resolve => setTimeout(resolve, ms));
+  }
+}
diff --git a/packages/ui/certd-server/src/modules/cert/service/tld-client.test.ts b/packages/ui/certd-server/src/modules/cert/service/tld-client.test.ts
index b0a961b10..65d723002 100644
--- a/packages/ui/certd-server/src/modules/cert/service/tld-client.test.ts
+++ b/packages/ui/certd-server/src/modules/cert/service/tld-client.test.ts
@@ -5,6 +5,7 @@ import assert from "node:assert/strict";
 
 import { http } from "@certd/basic";
 
+import { RdapSsClient } from "./rdap-ss-client.js";
 import { TldClient } from "./tld-client.js";
 
 describe("TldClient", () => {
@@ -35,10 +36,10 @@ describe("TldClient", () => {
   it("queries rdap.ss and parses HK whois date fields", async () => {
     const originalRequest = http.request;
     let requestedConfig: any;
-    const originalRequestTimes = (TldClient as any).rdapSsRequestTimes;
+    const originalRequestTimes = (RdapSsClient as any).requestTimes;
 
     try {
-      (TldClient as any).rdapSsRequestTimes = [];
+      (RdapSsClient as any).requestTimes = [];
       http.request = async (config: any) => {
         requestedConfig = config;
         return {
@@ -52,7 +53,7 @@ describe("TldClient", () => {
         };
       };
 
-      const result = await (new TldClient() as any).getDomainExpirationByRdapSs("google.com.hk");
+      const result = await new RdapSsClient().getDomainInfo("google.com.hk");
 
       assert.equal(requestedConfig.url, "https://rdap.ss/api/query?q=google.com.hk");
       assert.equal(requestedConfig.method, "GET");
@@ -60,67 +61,67 @@ describe("TldClient", () => {
       assert.equal(result.expirationDate, 1795104000000);
     } finally {
       http.request = originalRequest;
-      (TldClient as any).rdapSsRequestTimes = originalRequestTimes;
+      (RdapSsClient as any).requestTimes = originalRequestTimes;
     }
   });
 
   it("throws when rdap.ss rate-limit wait is over 3 minutes", async () => {
     const now = Date.now();
-    const originalRequestTimes = (TldClient as any).rdapSsRequestTimes;
+    const originalRequestTimes = (RdapSsClient as any).requestTimes;
 
     try {
-      (TldClient as any).rdapSsRequestTimes = Array.from({ length: 1200 }, () => now);
-      const client = new TldClient() as any;
+      (RdapSsClient as any).requestTimes = Array.from({ length: 1200 }, () => now);
+      const client = new RdapSsClient() as any;
       client.sleep = async () => {
         throw new Error("should not sleep when wait time is over limit");
       };
 
-      await assert.rejects(() => client.waitRdapSsRateLimit(), /rdap\.ss查询达到速率限制，等待时间超过3分钟/);
+      await assert.rejects(() => client.waitRateLimit(), /rdap\.ss查询达到速率限制，等待时间超过3分钟/);
     } finally {
-      (TldClient as any).rdapSsRequestTimes = originalRequestTimes;
+      (RdapSsClient as any).requestTimes = originalRequestTimes;
     }
   });
 
-  it("clears rdapSsRequestTimes entries older than 24 hours", async () => {
+  it("clears rdap.ss request time entries older than 24 hours", async () => {
     const now = Date.now();
-    const originalRequestTimes = (TldClient as any).rdapSsRequestTimes;
+    const originalRequestTimes = (RdapSsClient as any).requestTimes;
 
     try {
       const recentTime = now - 1000 * 60 * 60;
       const oldTime = now - 25 * 60 * 60 * 1000;
 
-      (TldClient as any).rdapSsRequestTimes = [oldTime, recentTime];
+      (RdapSsClient as any).requestTimes = [oldTime, recentTime];
 
-      const client = new TldClient() as any;
-      await client.waitRdapSsRateLimit();
+      const client = new RdapSsClient() as any;
+      await client.waitRateLimit();
 
-      const times = (TldClient as any).rdapSsRequestTimes;
+      const times = (RdapSsClient as any).requestTimes;
       assert.equal(times.length, 2);
       assert.ok(times.every((t: number) => now - t < 24 * 60 * 60 * 1000));
     } finally {
-      (TldClient as any).rdapSsRequestTimes = originalRequestTimes;
+      (RdapSsClient as any).requestTimes = originalRequestTimes;
     }
   });
 
-  it("keeps rdapSsRequestTimes entries within 24 hours and removes those exactly at boundary", async () => {
+  it("keeps rdap.ss request time entries within 24 hours and removes those exactly at boundary", async () => {
     const now = Date.now();
-    const originalRequestTimes = (TldClient as any).rdapSsRequestTimes;
+    const originalRequestTimes = (RdapSsClient as any).requestTimes;
 
     try {
       const boundaryTime = now - 24 * 60 * 60 * 1000;
       const withinTime = now - 23 * 60 * 60 * 1000;
 
-      (TldClient as any).rdapSsRequestTimes = [boundaryTime, withinTime];
+      (RdapSsClient as any).requestTimes = [boundaryTime, withinTime];
 
-      const client = new TldClient() as any;
-      await client.waitRdapSsRateLimit();
+      const client = new RdapSsClient() as any;
+      await client.waitRateLimit();
 
-      const times = (TldClient as any).rdapSsRequestTimes as number[];
+      const times = (RdapSsClient as any).requestTimes as number[];
       assert.equal(times.length, 2);
       assert.ok(times.every((t: number) => now - t < 24 * 60 * 60 * 1000));
       assert.ok(times.includes(withinTime));
     } finally {
-      (TldClient as any).rdapSsRequestTimes = originalRequestTimes;
+      (RdapSsClient as any).requestTimes = originalRequestTimes;
     }
   });
 });
diff --git a/packages/ui/certd-server/src/modules/cert/service/tld-client.ts b/packages/ui/certd-server/src/modules/cert/service/tld-client.ts
index cfd3f4a86..ee277ac7b 100644
--- a/packages/ui/certd-server/src/modules/cert/service/tld-client.ts
+++ b/packages/ui/certd-server/src/modules/cert/service/tld-client.ts
@@ -3,6 +3,8 @@ import { parseDomainByPsl } from "@certd/plugin-lib";
 import dayjs from "dayjs";
 import customParseFormat from "dayjs/plugin/customParseFormat.js";
 
+import { RdapSsClient } from "./rdap-ss-client.js";
+
 dayjs.extend(customParseFormat);
 
 export interface DomainInfo {
@@ -11,16 +13,7 @@ export interface DomainInfo {
 }
 
 export class TldClient {
-  private static readonly RDAP_SS_API = "https://rdap.ss/api/query";
-  private static readonly RDAP_SS_RATE_LIMITS = [
-    { windowMs: 60 * 1000, max: 30 },
-    { windowMs: 60 * 60 * 1000, max: 1200 },
-    { windowMs: 24 * 60 * 60 * 1000, max: 12000 },
-  ];
-  private static readonly RDAP_SS_MAX_WAIT_MS = 3 * 60 * 1000;
-  private static readonly RDAP_SS_DATA_RETENTION_MS = 24 * 60 * 60 * 1000;
-  private static rdapSsRequestTimes: number[] = [];
-
+  private rdapSsClient = new RdapSsClient();
   private rdapMap: Record<string, string> = {};
   private isInitialized = false;
 
@@ -93,35 +86,7 @@ export class TldClient {
   }
 
   private async getDomainExpirationByRdapSs(domain: string): Promise<DomainInfo> {
-    await this.waitRdapSsRateLimit();
-
-    const result = await http.request({
-      url: `${TldClient.RDAP_SS_API}?q=${encodeURIComponent(domain)}`,
-      method: "GET",
-      logRes: false,
-    });
-
-    if (!result?.success || !result?.data) {
-      throw new Error(`【${domain}】rdap.ss查询失败`);
-    }
-
-    const data = result.data?.whoisData || result.data?.rawData || {};
-    const res: DomainInfo = {};
-    const expirationDate = this.parseFirstDate(data, ["Expiry Date", "Expiration Date", "Registry Expiry Date", "expires"]);
-    const registrationDate = this.parseFirstDate(data, ["Domain Name Commencement Date", "Created Date", "Creation Date", "Registration Date", "Registered On"]);
-
-    if (expirationDate) {
-      res.expirationDate = expirationDate;
-    }
-    if (registrationDate) {
-      res.registrationDate = registrationDate;
-    }
-
-    if (!res.expirationDate) {
-      throw new Error(`【${domain}】rdap.ss查询未找到过期时间`);
-    }
-
-    return res;
+    return await this.rdapSsClient.getDomainInfo(domain);
   }
 
   private async getDomainExpirationByWhoiser(domain: string): Promise<DomainInfo> {
@@ -175,70 +140,6 @@ export class TldClient {
     return res;
   }
 
-  private async waitRdapSsRateLimit() {
-    while (true) {
-      const now = Date.now();
-      TldClient.rdapSsRequestTimes = TldClient.rdapSsRequestTimes.filter(time => now - time < TldClient.RDAP_SS_DATA_RETENTION_MS);
-
-      const waitMs = TldClient.RDAP_SS_RATE_LIMITS.reduce((maxWaitMs, limit) => {
-        const times = TldClient.rdapSsRequestTimes.filter(time => now - time < limit.windowMs);
-        if (times.length < limit.max) {
-          return maxWaitMs;
-        }
-        const earliestTime = Math.min(...times);
-        return Math.max(maxWaitMs, earliestTime + limit.windowMs - now);
-      }, 0);
-
-      if (waitMs <= 0) {
-        TldClient.rdapSsRequestTimes.push(now);
-        return;
-      }
-
-      if (waitMs > TldClient.RDAP_SS_MAX_WAIT_MS) {
-        throw new Error(`rdap.ss查询达到速率限制，等待时间超过3分钟`);
-      }
-
-      logger.warn(`rdap.ss查询达到速率限制，将在${waitMs}ms后重试`);
-      await this.sleep(waitMs);
-    }
-  }
-
-  private parseFirstDate(data: Record<string, any>, keys: string[]) {
-    for (const key of keys) {
-      const value = data[key];
-      const values = Array.isArray(value) ? value : [value];
-      for (const item of values) {
-        const timestamp = this.parseDateValue(item);
-        if (timestamp) {
-          return timestamp;
-        }
-      }
-    }
-  }
-
-  private parseDateValue(value: any) {
-    if (!value || typeof value !== "string") {
-      return;
-    }
-
-    const formats = ["DD-MM-YYYY", "YYYY-MM-DD", "YYYY-MM-DD HH:mm:ss", "YYYY/MM/DD", "YYYY/MM/DD HH:mm:ss", "MMM D YYYY", "MMM D, YYYY"];
-    for (const format of formats) {
-      const parsed = dayjs(value, format, true);
-      if (parsed.isValid()) {
-        return parsed.valueOf();
-      }
-    }
-
-    const parsed = dayjs(value);
-    if (parsed.isValid()) {
-      return parsed.valueOf();
-    }
-  }
-
-  private sleep(ms: number) {
-    return new Promise(resolve => setTimeout(resolve, ms));
-  }
-
   private getErrorMessage(error: unknown) {
     if (error instanceof Error) {
       return error.message;