diff --git a/Overlord-Server/public/assets/sol-publish.js b/Overlord-Server/public/assets/sol-publish.js
index 8c1aaa2..19336f8 100644
--- a/Overlord-Server/public/assets/sol-publish.js
+++ b/Overlord-Server/public/assets/sol-publish.js
@@ -15,11 +15,15 @@ const rpcEndpointList = document.getElementById("rpc-endpoint-list");
 const newRpcInput = document.getElementById("new-rpc-url");
 const addRpcBtn = document.getElementById("add-rpc-btn");
 const rpcManagerError = document.getElementById("rpc-manager-error");
+const testAllRpcBtn = document.getElementById("test-all-rpc-btn");
+const rpcTestSummary = document.getElementById("rpc-test-summary");
 
-if (!rpcSelect || !customRpcWrapper || !customRpcInput || !privateKeyInput || !toggleKeyBtn || !serverUrlInput || !previewBtn || !publishBtn || !outputSection || !outputDiv || !walletInfo || !walletAddress || !rpcEndpointList || !newRpcInput || !addRpcBtn || !rpcManagerError) {
+if (!rpcSelect || !customRpcWrapper || !customRpcInput || !privateKeyInput || !toggleKeyBtn || !serverUrlInput || !previewBtn || !publishBtn || !outputSection || !outputDiv || !walletInfo || !walletAddress || !rpcEndpointList || !newRpcInput || !addRpcBtn || !rpcManagerError || !testAllRpcBtn || !rpcTestSummary) {
   return;
 }
 
+let rpcTestResults = new Map();
+
 function normalizeRpcEndpoints(value) {
   const seen = new Set();
   const endpoints = [];
@@ -75,8 +79,11 @@ function renderRpcEndpointManager(records) {
     return;
   }
   records.forEach((record) => {
+    const testResult = rpcTestResults.get(record.id);
     const row = document.createElement("div");
-    row.className = "group flex items-center gap-1 rounded-lg border border-slate-800 bg-slate-950/60 p-1.5";
+    row.className = `group flex flex-wrap items-center gap-1 rounded-lg border bg-slate-950/60 p-1.5 ${
+      testResult ? (testResult.ok ? "border-emerald-500/40" : "border-red-500/40") : "border-slate-800"
+    }`;
     const input = document.createElement("input");
     input.type = "url";
     input.value = record.url;
@@ -94,10 +101,51 @@ function renderRpcEndpointManager(records) {
     remove.innerHTML = '<i class="fa-solid fa-trash"></i>';
     remove.addEventListener("click", () => mutateRpcEndpoint(`/api/sol/rpc-endpoints/${record.id}`, "DELETE"));
     row.append(input, save, remove);
+    if (testResult) {
+      const status = document.createElement("div");
+      status.className = `basis-full px-2 pb-1 text-[11px] ${testResult.ok ? "text-emerald-300" : "text-red-300"}`;
+      status.title = testResult.ok ? `Latest blockhash: ${testResult.blockhash}` : testResult.error;
+      status.innerHTML = testResult.ok
+        ? `<i class="fa-solid fa-circle-check mr-1"></i>Valid response · ${testResult.latencyMs} ms · slot ${testResult.slot.toLocaleString()} · block height ${testResult.lastValidBlockHeight.toLocaleString()}`
+        : `<i class="fa-solid fa-circle-xmark mr-1"></i>${escapeHtml(testResult.error || "RPC test failed")} · ${testResult.latencyMs} ms`;
+      row.appendChild(status);
+    }
     rpcEndpointList.appendChild(row);
   });
 }
 
+function escapeHtml(value) {
+  const element = document.createElement("span");
+  element.textContent = String(value);
+  return element.innerHTML;
+}
+
+testAllRpcBtn.addEventListener("click", async () => {
+  setRpcManagerError();
+  rpcTestSummary.classList.add("hidden");
+  testAllRpcBtn.disabled = true;
+  testAllRpcBtn.innerHTML = '<i class="fa-solid fa-spinner fa-spin"></i> Testing...';
+  try {
+    const res = await fetch("/api/sol/rpc-endpoints/test", {
+      method: "POST",
+      credentials: "include",
+    });
+    const data = await res.json();
+    if (!res.ok) throw new Error(data?.error || "Failed to test RPC endpoints");
+    rpcTestResults = new Map((data.results || []).map((result) => [result.id, result]));
+    rpcTestSummary.textContent = `${data.passed} of ${data.tested} endpoints returned a valid Solana blockhash${data.failed ? `; ${data.failed} failed` : "."}`;
+    rpcTestSummary.className = `rounded-lg border px-3 py-2 text-xs ${
+      data.failed ? "border-amber-500/30 bg-amber-500/5 text-amber-200" : "border-emerald-500/30 bg-emerald-500/5 text-emerald-200"
+    }`;
+    await loadRpcEndpoints();
+  } catch (error) {
+    setRpcManagerError(error?.message || "Failed to test RPC endpoints");
+  } finally {
+    testAllRpcBtn.disabled = false;
+    testAllRpcBtn.innerHTML = '<i class="fa-solid fa-vial"></i> Test all';
+  }
+});
+
 async function mutateRpcEndpoint(path, method, body) {
   setRpcManagerError();
   try {
@@ -110,6 +158,8 @@ async function mutateRpcEndpoint(path, method, body) {
     const data = await res.json();
     if (!res.ok) throw new Error(data?.error || "Failed to save RPC endpoints");
     newRpcInput.value = "";
+    rpcTestResults.clear();
+    rpcTestSummary.classList.add("hidden");
     await loadRpcEndpoints();
   } catch (error) {
     setRpcManagerError(error?.message || "Failed to save RPC endpoints");
diff --git a/Overlord-Server/public/sol-publish.html b/Overlord-Server/public/sol-publish.html
index 5a00b32..85aceab 100644
--- a/Overlord-Server/public/sol-publish.html
+++ b/Overlord-Server/public/sol-publish.html
@@ -135,9 +135,14 @@
                 <h2 class="text-base font-semibold">RPC endpoint pool</h2>
                 <p class="text-xs text-slate-400">Shared by future client builds.</p>
               </div>
+              <button type="button" id="test-all-rpc-btn"
+                class="ml-auto shrink-0 inline-flex items-center justify-center gap-1.5 px-3 py-2 rounded-lg bg-sky-600 hover:bg-sky-500 text-white border border-sky-500 text-xs font-semibold transition-colors disabled:opacity-50">
+                <i class="fa-solid fa-vial"></i> Test all
+              </button>
             </div>
 
             <div id="rpc-endpoint-list" class="space-y-2"></div>
+            <div id="rpc-test-summary" class="hidden rounded-lg border px-3 py-2 text-xs"></div>
 
             <div class="pt-3 border-t border-slate-800 space-y-2">
               <label class="block text-xs font-semibold uppercase tracking-wider text-slate-500" for="new-rpc-url">Add endpoint</label>
diff --git a/Overlord-Server/src/server/routes/sol-routes.ts b/Overlord-Server/src/server/routes/sol-routes.ts
index 41cee55..034d9eb 100644
--- a/Overlord-Server/src/server/routes/sol-routes.ts
+++ b/Overlord-Server/src/server/routes/sol-routes.ts
@@ -9,6 +9,7 @@ import {
   normalizeSolRpcUrl,
   saveSolRpcEndpointUrls,
 } from "../../sol-rpc-endpoints";
+import { testSolRpcEndpoint } from "../../sol-rpc-test";
 
 let _solana: typeof import("@solana/web3.js") | null = null;
 async function getSolana() {
@@ -73,6 +74,20 @@ export async function handleSolRoutes(
     try { requirePermission(user, "system:configure"); }
     catch (error) { return error instanceof Response ? error : new Response("Forbidden", { status: 403 }); }
 
+    if (req.method === "POST" && url.pathname === "/api/sol/rpc-endpoints/test") {
+      const records = getSolRpcEndpoints();
+      const results = await Promise.all(records.map(async (record) => ({
+        ...record,
+        ...await testSolRpcEndpoint(record.url),
+      })));
+      return Response.json({
+        tested: results.length,
+        passed: results.filter((result) => result.ok).length,
+        failed: results.filter((result) => !result.ok).length,
+        results,
+      });
+    }
+
     if (req.method === "POST" && url.pathname === "/api/sol/rpc-endpoints") {
       const body = await req.json();
       const current = getSolRpcEndpoints().map((item) => item.url);
diff --git a/Overlord-Server/src/sol-rpc-test.test.ts b/Overlord-Server/src/sol-rpc-test.test.ts
new file mode 100644
index 0000000..c929e02
--- /dev/null
+++ b/Overlord-Server/src/sol-rpc-test.test.ts
@@ -0,0 +1,62 @@
+import { describe, expect, test } from "bun:test";
+import { testSolRpcEndpoint } from "./sol-rpc-test";
+
+const validBlockhash = "11111111111111111111111111111111";
+
+describe("testSolRpcEndpoint", () => {
+  test("accepts a valid latest blockhash response", async () => {
+    const fetchImpl = async () => Response.json({
+      jsonrpc: "2.0",
+      id: 1,
+      result: {
+        context: { slot: 123456 },
+        value: { blockhash: validBlockhash, lastValidBlockHeight: 123600 },
+      },
+    });
+
+    const result = await testSolRpcEndpoint("https://rpc.example.com", 100, fetchImpl);
+    expect(result).toMatchObject({
+      ok: true,
+      slot: 123456,
+      blockhash: validBlockhash,
+      lastValidBlockHeight: 123600,
+    });
+  });
+
+  test("rejects successful HTTP responses with invalid RPC values", async () => {
+    const fetchImpl = async () => Response.json({
+      jsonrpc: "2.0",
+      id: 1,
+      result: { context: { slot: "not-a-number" }, value: {} },
+    });
+
+    const result = await testSolRpcEndpoint("https://rpc.example.com", 100, fetchImpl);
+    expect(result.ok).toBe(false);
+    expect(result.error).toBe("Response contained an invalid slot");
+  });
+
+  test("reports HTTP and JSON-RPC errors", async () => {
+    const httpResult = await testSolRpcEndpoint(
+      "https://rpc.example.com",
+      100,
+      async () => new Response("unavailable", { status: 503 }),
+    );
+    expect(httpResult).toMatchObject({ ok: false, error: "HTTP 503" });
+
+    const rpcResult = await testSolRpcEndpoint(
+      "https://rpc.example.com",
+      100,
+      async () => Response.json({ error: { message: "rate limited" } }),
+    );
+    expect(rpcResult).toMatchObject({ ok: false, error: "rate limited" });
+  });
+
+  test("aborts endpoints that exceed the timeout", async () => {
+    const fetchImpl = (_input: string | URL | Request, init?: RequestInit) => new Promise<Response>((_resolve, reject) => {
+      init?.signal?.addEventListener("abort", () => reject(new DOMException("Aborted", "AbortError")));
+    });
+
+    const result = await testSolRpcEndpoint("https://rpc.example.com", 5, fetchImpl);
+    expect(result).toMatchObject({ ok: false, error: "Timed out after 5ms" });
+  });
+});
diff --git a/Overlord-Server/src/sol-rpc-test.ts b/Overlord-Server/src/sol-rpc-test.ts
new file mode 100644
index 0000000..3c46962
--- /dev/null
+++ b/Overlord-Server/src/sol-rpc-test.ts
@@ -0,0 +1,80 @@
+const BASE58_VALUE = /^[1-9A-HJ-NP-Za-km-z]{32,64}$/;
+
+export type SolRpcTestResult = {
+  ok: boolean;
+  latencyMs: number;
+  slot?: number;
+  blockhash?: string;
+  lastValidBlockHeight?: number;
+  error?: string;
+};
+
+type RpcFetch = (input: string | URL | Request, init?: RequestInit) => Promise<Response>;
+
+export async function testSolRpcEndpoint(
+  endpoint: string,
+  timeoutMs = 10_000,
+  fetchImpl: RpcFetch = fetch,
+): Promise<SolRpcTestResult> {
+  const startedAt = performance.now();
+  const controller = new AbortController();
+  const timeout = setTimeout(() => controller.abort(), timeoutMs);
+
+  try {
+    const response = await fetchImpl(endpoint, {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({
+        jsonrpc: "2.0",
+        id: 1,
+        method: "getLatestBlockhash",
+        params: [{ commitment: "confirmed" }],
+      }),
+      signal: controller.signal,
+    });
+
+    if (!response.ok) {
+      throw new Error(`HTTP ${response.status}${response.statusText ? ` ${response.statusText}` : ""}`);
+    }
+
+    let data: any;
+    try {
+      data = await response.json();
+    } catch {
+      throw new Error("Response was not valid JSON");
+    }
+
+    if (data?.error) {
+      const detail = typeof data.error.message === "string" ? data.error.message : "RPC returned an error";
+      throw new Error(detail);
+    }
+
+    const slot = data?.result?.context?.slot;
+    const blockhash = data?.result?.value?.blockhash;
+    const lastValidBlockHeight = data?.result?.value?.lastValidBlockHeight;
+    if (!Number.isSafeInteger(slot) || slot < 0) throw new Error("Response contained an invalid slot");
+    if (typeof blockhash !== "string" || !BASE58_VALUE.test(blockhash)) {
+      throw new Error("Response contained an invalid blockhash");
+    }
+    if (!Number.isSafeInteger(lastValidBlockHeight) || lastValidBlockHeight < 0) {
+      throw new Error("Response contained an invalid last valid block height");
+    }
+
+    return {
+      ok: true,
+      latencyMs: Math.round(performance.now() - startedAt),
+      slot,
+      blockhash,
+      lastValidBlockHeight,
+    };
+  } catch (error: any) {
+    const timedOut = controller.signal.aborted;
+    return {
+      ok: false,
+      latencyMs: Math.round(performance.now() - startedAt),
+      error: timedOut ? `Timed out after ${timeoutMs}ms` : (error?.message || "RPC request failed"),
+    };
+  } finally {
+    clearTimeout(timeout);
+  }
+}