diff --git a/packages/browser-tests/src/server.ts b/packages/browser-tests/src/server.ts
index a912b39b20..3772f419e9 100644
--- a/packages/browser-tests/src/server.ts
+++ b/packages/browser-tests/src/server.ts
@@ -7,7 +7,7 @@ import { Logger } from "@waku/utils";
 
 import wakuRouter from "./routes/waku.js";
 import { initBrowser, getPage, closeBrowser } from "./browser/index.js";
-import { DEFAULT_CLUSTER_ID, DEFAULT_NUM_SHARDS } from "@waku/interfaces";
+import { DEFAULT_CLUSTER_ID, DEFAULT_NUM_SHARDS, Protocols } from "@waku/interfaces";
 
 const log = new Logger("server");
 const app = express();
@@ -144,7 +144,7 @@ async function startServer(port: number = 3000): Promise<void> {
 
       try {
         await getPage()?.evaluate(() =>
-          window.wakuApi.waitForPeers?.(5000, ["lightpush"] as any),
+          window.wakuApi.waitForPeers?.(5000, [Protocols.LightPush]),
         );
         log.info("Auto-start completed with bootstrap peers");
       } catch (peerError) {
diff --git a/packages/browser-tests/src/utils/endpoint-handler.ts b/packages/browser-tests/src/utils/endpoint-handler.ts
index 2318777be9..be1caacc22 100644
--- a/packages/browser-tests/src/utils/endpoint-handler.ts
+++ b/packages/browser-tests/src/utils/endpoint-handler.ts
@@ -78,7 +78,8 @@ export function createEndpointHandler<TInput = any, TOutput = any>(
             throw new Error("window.wakuApi is not available");
           }
 
-          const method = (testWindow.wakuApi as any)[methodName];
+          const wakuApi = testWindow.wakuApi as unknown as Record<string, unknown>;
+          const method = wakuApi[methodName];
           if (typeof method !== "function") {
             throw new Error(`window.wakuApi.${methodName} is not a function`);
           }
diff --git a/packages/browser-tests/tests/utils/container-helpers.ts b/packages/browser-tests/tests/utils/container-helpers.ts
index c643ce8374..d65686a544 100644
--- a/packages/browser-tests/tests/utils/container-helpers.ts
+++ b/packages/browser-tests/tests/utils/container-helpers.ts
@@ -117,9 +117,10 @@ export async function stopContainer(container: StartedTestContainer): Promise<vo
     await container.stop({ timeout: 10000 });
     log.info("Container stopped successfully");
   } catch (error) {
+    const message = error instanceof Error ? error.message : String(error);
     log.warn(
       "Container stop had issues (expected):",
-      (error as any).message
+      message
     );
   }
 }
\ No newline at end of file
diff --git a/packages/browser-tests/tests/utils/nwaku-helpers.ts b/packages/browser-tests/tests/utils/nwaku-helpers.ts
index c3c2b1ba7c..8b7466b5f0 100644
--- a/packages/browser-tests/tests/utils/nwaku-helpers.ts
+++ b/packages/browser-tests/tests/utils/nwaku-helpers.ts
@@ -51,10 +51,11 @@ export async function createTwoNodeNetwork(): Promise<ServiceNodesFleet> {
   await verifyNetworkFormation([lightPushNode, relayNode]);
 
   // Return ServiceNodesFleet-compatible object
+  // Note: We're returning a partial ServiceNodesFleet for testing purposes
   return {
     nodes: [lightPushNode, relayNode],
-    messageCollector: null as any // Not needed for these tests
-  } as any;
+    messageCollector: null
+  } as ServiceNodesFleet;
 }
 
 /**
@@ -97,8 +98,10 @@ export async function getDockerAccessibleMultiaddr(node: ServiceNode): Promise<s
     throw new Error("Could not extract port from multiaddr: " + multiaddrStr);
   }
 
-  // Get Docker container IP (accessing private field safely)
-  const containerIp = (node as any).docker?.containerIp;
+  // Get Docker container IP (accessing internal field)
+  // Note: This accesses an internal implementation detail of ServiceNode
+  const nodeWithDocker = node as ServiceNode & { docker?: { containerIp?: string } };
+  const containerIp = nodeWithDocker.docker?.containerIp;
   if (!containerIp) {
     throw new Error("Could not get container IP from node");
   }
@@ -123,6 +126,7 @@ export async function stopNwakuNodes(nodes: ServiceNode[]): Promise<void> {
     await Promise.all(nodes.map(node => node.stop()));
     log.info("Nwaku nodes stopped successfully");
   } catch (error) {
-    log.warn("Nwaku nodes stop had issues:", (error as any).message);
+    const message = error instanceof Error ? error.message : String(error);
+    log.warn("Nwaku nodes stop had issues:", message);
   }
 }
diff --git a/packages/browser-tests/web/index.ts b/packages/browser-tests/web/index.ts
index 5834dd0781..e17f4ffd51 100644
--- a/packages/browser-tests/web/index.ts
+++ b/packages/browser-tests/web/index.ts
@@ -11,9 +11,11 @@ import {
   DEFAULT_NUM_SHARDS,
   ShardId,
   StaticSharding,
+  ShardInfo,
 } from "@waku/interfaces";
 import { bootstrap } from "@libp2p/bootstrap";
 import { EnrDecoder, TransportProtocol } from "@waku/enr";
+import type { Multiaddr } from "@multiformats/multiaddr";
 import type { ITestBrowser } from "../types/global.js";
 import { Logger, StaticShardingRoutingInfo } from "@waku/utils";
 
@@ -78,7 +80,7 @@ export class WakuHeadless {
     lightpushNode?: string | null,
     enrBootstrap?: string | null,
   ) {
-    this.waku = null as unknown as LightNode;
+    this.waku = null;
     this.networkConfig = this.buildNetworkConfig(networkConfig);
     log.info("Network config on construction:", this.networkConfig);
     this.lightpushNode = lightpushNode || null;
@@ -118,11 +120,11 @@ export class WakuHeadless {
   }
 
   private buildNetworkConfig(
-    providedConfig?: Partial<NetworkConfig>,
+    providedConfig?: Partial<NetworkConfig> | Partial<ShardInfo>,
   ): NetworkConfig {
     const clusterId = providedConfig?.clusterId ?? DEFAULT_CLUSTER_ID;
 
-    const staticShards = (providedConfig as any)?.shards;
+    const staticShards = (providedConfig as Partial<ShardInfo>)?.shards;
     if (
       staticShards &&
       Array.isArray(staticShards) &&
@@ -135,7 +137,7 @@ export class WakuHeadless {
     }
 
     const numShardsInCluster =
-      (providedConfig as any)?.numShardsInCluster ?? DEFAULT_NUM_SHARDS;
+      (providedConfig as Partial<AutoSharding>)?.numShardsInCluster ?? DEFAULT_NUM_SHARDS;
     log.info(
       "Using auto sharding with num shards in cluster:",
       numShardsInCluster,
@@ -374,7 +376,7 @@ export class WakuHeadless {
     const addrs = this.waku.libp2p.getMultiaddrs();
     return {
       peerId: this.waku.libp2p.peerId.toString(),
-      multiaddrs: addrs.map((a: any) => a.toString()),
+      multiaddrs: addrs.map((a: Multiaddr) => a.toString()),
       peers: [],
     };
   }
@@ -400,10 +402,19 @@ export class WakuHeadless {
   } catch (error) {
     log.error("Error initializing WakuHeadless:", error);
     const testWindow = window as ITestBrowser;
+    // Create a stub wakuApi that will reject all method calls
     testWindow.wakuApi = {
-      start: () =>
-        Promise.reject(new Error("WakuHeadless failed to initialize")),
-      error: error,
-    } as any;
+      waku: null,
+      networkConfig: { clusterId: 0, numShardsInCluster: 0 },
+      lightpushNode: null,
+      enrBootstrap: null,
+      error,
+      createWakuNode: () => Promise.reject(new Error("WakuHeadless failed to initialize")),
+      startNode: () => Promise.reject(new Error("WakuHeadless failed to initialize")),
+      stopNode: () => Promise.reject(new Error("WakuHeadless failed to initialize")),
+      pushMessageV3: () => Promise.reject(new Error("WakuHeadless failed to initialize")),
+      waitForPeers: () => Promise.reject(new Error("WakuHeadless failed to initialize")),
+      getPeerInfo: () => { throw new Error("WakuHeadless failed to initialize"); },
+    } as unknown as WakuHeadless;
   }
 })();