diff --git a/packages/controller/src/__tests__/controllerDefaults.test.ts b/packages/controller/src/__tests__/controllerDefaults.test.ts
index a1613dc2f4..7ad43b7cad 100644
--- a/packages/controller/src/__tests__/controllerDefaults.test.ts
+++ b/packages/controller/src/__tests__/controllerDefaults.test.ts
@@ -41,30 +41,30 @@ describe("ControllerProvider defaults", () => {
     );
   });
 
-  test("should throw error when using non-Cartridge RPC for mainnet", async () => {
-    const invalidChains = [
+  test("should allow non-Cartridge RPC for mainnet", async () => {
+    const customChains = [
       { rpcUrl: "https://some-other-provider.com/starknet/mainnet/rpc/v0_9" },
     ];
 
     expect(() => {
       new ControllerProvider({
-        chains: invalidChains,
+        chains: customChains,
         defaultChainId: constants.StarknetChainId.SN_MAIN,
       });
-    }).toThrow("Only Cartridge RPC providers are allowed for mainnet");
+    }).not.toThrow();
   });
 
-  test("should throw error when using non-Cartridge RPC for sepolia", async () => {
-    const invalidChains = [
+  test("should allow non-Cartridge RPC for sepolia", async () => {
+    const customChains = [
       { rpcUrl: "https://some-other-provider.com/starknet/sepolia/rpc/v0_9" },
     ];
 
     expect(() => {
       new ControllerProvider({
-        chains: invalidChains,
+        chains: customChains,
         defaultChainId: constants.StarknetChainId.SN_SEPOLIA,
       });
-    }).toThrow("Only Cartridge RPC providers are allowed for sepolia");
+    }).not.toThrow();
   });
 
   test("should allow non-Cartridge RPC for custom chains", () => {
diff --git a/packages/controller/src/__tests__/parseChainId.test.ts b/packages/controller/src/__tests__/parseChainId.test.ts
index df907d36b6..dc073fe902 100644
--- a/packages/controller/src/__tests__/parseChainId.test.ts
+++ b/packages/controller/src/__tests__/parseChainId.test.ts
@@ -42,17 +42,25 @@ describe("parseChainId", () => {
     });
   });
 
+  describe("Non-Cartridge hosts", () => {
+    test("returns placeholder chainId in Node", () => {
+      expect(parseChainId(new URL("http://dl:123123"))).toBe(
+        shortString.encodeShortString("LOCALHOST"),
+      );
+    });
+  });
+
   describe("Error cases", () => {
     test("throws error for unsupported URL format", () => {
       expect(() =>
-        parseChainId(new URL("https://api.example.com/unsupported")),
-      ).toThrow("Chain https://api.example.com/unsupported not supported");
+        parseChainId(new URL("https://api.cartridge.gg/unsupported")),
+      ).toThrow("Chain https://api.cartridge.gg/unsupported not supported");
     });
 
     test("throws error for URLs without proper chain identifiers", () => {
       expect(() =>
-        parseChainId(new URL("https://api.example.com/v1/starknet")),
-      ).toThrow("Chain https://api.example.com/v1/starknet not supported");
+        parseChainId(new URL("https://api.cartridge.gg/v1/starknet")),
+      ).toThrow("Chain https://api.cartridge.gg/v1/starknet not supported");
     });
   });
 });
diff --git a/packages/controller/src/controller.ts b/packages/controller/src/controller.ts
index c801df32f8..5f587e27f4 100644
--- a/packages/controller/src/controller.ts
+++ b/packages/controller/src/controller.ts
@@ -570,20 +570,6 @@ export default class ControllerProvider extends BaseProvider {
         const url = new URL(chain.rpcUrl);
         const chainId = parseChainId(url);
 
-        // Validate that mainnet and sepolia must use Cartridge RPC
-        const isMainnet = chainId === constants.StarknetChainId.SN_MAIN;
-        const isSepolia = chainId === constants.StarknetChainId.SN_SEPOLIA;
-        const isCartridgeRpc = url.hostname === "api.cartridge.gg";
-        const isLocalhost =
-          url.hostname === "localhost" || url.hostname === "127.0.0.1";
-
-        if ((isMainnet || isSepolia) && !(isCartridgeRpc || isLocalhost)) {
-          throw new Error(
-            `Only Cartridge RPC providers are allowed for ${isMainnet ? "mainnet" : "sepolia"}. ` +
-              `Please use: https://api.cartridge.gg/x/starknet/${isMainnet ? "mainnet" : "sepolia"}/rpc/v0_9`,
-          );
-        }
-
         this.chains.set(chainId, chain);
       } catch (error) {
         console.error(`Failed to parse chainId for ${chain.rpcUrl}:`, error);
diff --git a/packages/controller/src/utils.ts b/packages/controller/src/utils.ts
index 4a9fff06a1..20de1f738e 100644
--- a/packages/controller/src/utils.ts
+++ b/packages/controller/src/utils.ts
@@ -138,17 +138,14 @@ export function humanizeString(str: string): string {
 
 export function parseChainId(url: URL): ChainId {
   const parts = url.pathname.split("/");
+  const isCartridgeHost = url.hostname === "api.cartridge.gg";
 
-  // Handle localhost URLs by making a synchronous call to getChainId
-  if (
-    url.hostname === "localhost" ||
-    url.hostname === "127.0.0.1" ||
-    url.hostname === "0.0.0.0"
-  ) {
+  // Handle non-Cartridge hosts by making a synchronous call to getChainId
+  if (!isCartridgeHost) {
     // Check if we're in a browser environment
     if (typeof XMLHttpRequest === "undefined") {
       // In Node.js environment (like tests), we can't make synchronous HTTP calls
-      // For now, we'll use a placeholder chainId for localhost in tests
+      // For now, we'll use a placeholder chainId for non-Cartridge hosts in tests
       console.warn(
         `Cannot make synchronous HTTP call in Node.js environment for ${url.toString()}`,
       );