diff --git a/backend/src/api/mempool-blocks.ts b/backend/src/api/mempool-blocks.ts
index a39330d5e..ad32bfc57 100644
--- a/backend/src/api/mempool-blocks.ts
+++ b/backend/src/api/mempool-blocks.ts
@@ -26,23 +26,23 @@ class MempoolBlocks {
 
   private calculateMempoolBlocks(transactionsSorted: TransactionExtended[]): MempoolBlock[] {
     const mempoolBlocks: MempoolBlock[] = [];
-    let blockWeight = 0;
+    let blockVSize = 0;
     let blockSize = 0;
     let transactions: TransactionExtended[] = [];
     transactionsSorted.forEach((tx) => {
-      if (blockWeight + tx.vsize < 1000000 || mempoolBlocks.length === config.DEFAULT_PROJECTED_BLOCKS_AMOUNT - 1) {
-        blockWeight += tx.vsize;
+      if (blockVSize + tx.vsize <= 1000000 || mempoolBlocks.length === config.DEFAULT_PROJECTED_BLOCKS_AMOUNT - 1) {
+        blockVSize += tx.vsize;
         blockSize += tx.size;
         transactions.push(tx);
       } else {
-        mempoolBlocks.push(this.dataToMempoolBlocks(transactions, blockSize, blockWeight, mempoolBlocks.length));
-        blockWeight = 0;
+        mempoolBlocks.push(this.dataToMempoolBlocks(transactions, blockSize, blockVSize, mempoolBlocks.length));
+        blockVSize = 0;
         blockSize = 0;
         transactions = [];
       }
     });
     if (transactions.length) {
-      mempoolBlocks.push(this.dataToMempoolBlocks(transactions, blockSize, blockWeight, mempoolBlocks.length));
+      mempoolBlocks.push(this.dataToMempoolBlocks(transactions, blockSize, blockVSize, mempoolBlocks.length));
     }
     return mempoolBlocks;
   }
diff --git a/backend/src/api/mempool.ts b/backend/src/api/mempool.ts
index b150c9738..abc6a5c46 100644
--- a/backend/src/api/mempool.ts
+++ b/backend/src/api/mempool.ts
@@ -4,7 +4,7 @@ import { MempoolInfo, TransactionExtended, Transaction } from '../interfaces';
 
 class Mempool {
   private inSync: boolean = false;
-  private mempoolCache: any = {};
+  private mempoolCache: { [txId: string]: TransactionExtended } = {};
   private mempoolInfo: MempoolInfo = { size: 0, bytes: 0 };
   private mempoolChangedCallback: Function | undefined;
 
@@ -30,7 +30,7 @@ class Mempool {
     return this.mempoolCache;
   }
 
-  public setMempool(mempoolData: any) {
+  public setMempool(mempoolData: { [txId: string]: TransactionExtended }) {
     this.mempoolCache = mempoolData;
     if (this.mempoolChangedCallback && mempoolData) {
       this.mempoolChangedCallback(mempoolData);
diff --git a/backend/src/api/websocket-handler.ts b/backend/src/api/websocket-handler.ts
index 339e8efd5..1f58b7d20 100644
--- a/backend/src/api/websocket-handler.ts
+++ b/backend/src/api/websocket-handler.ts
@@ -25,7 +25,7 @@ class WebsocketHandler {
     }
 
     this.wss.on('connection', (client: WebSocket) => {
-      client.on('message', (message: any) => {
+      client.on('message', (message: string) => {
         try {
           const parsedMessage: WebsocketResponse = JSON.parse(message);
           const response = {};
diff --git a/backend/src/index.ts b/backend/src/index.ts
index ffb23bfaa..ab72d260b 100644
--- a/backend/src/index.ts
+++ b/backend/src/index.ts
@@ -1,4 +1,5 @@
 const config = require('../mempool-config.json');
+import { Express, Request, Response, NextFunction } from 'express';
 import * as fs from 'fs';
 import * as express from 'express';
 import * as compression from 'compression';
@@ -17,13 +18,13 @@ import fiatConversion from './api/fiat-conversion';
 class Server {
   wss: WebSocket.Server;
   server: https.Server | http.Server;
-  app: any;
+  app: Express;
 
   constructor() {
     this.app = express();
 
     this.app
-      .use((req, res, next) => {
+      .use((req: Request, res: Response, next: NextFunction) => {
         res.setHeader('Access-Control-Allow-Origin', '*');
         next();
       })
diff --git a/backend/src/routes.ts b/backend/src/routes.ts
index 20df6ca87..3240489fe 100644
--- a/backend/src/routes.ts
+++ b/backend/src/routes.ts
@@ -1,3 +1,4 @@
+import { Request, Response } from 'express';
 import statistics from './api/statistics';
 import feeApi from './api/fee-api';
 import backendInfo from './api/backend-info';
@@ -22,60 +23,66 @@ class Routes {
     console.log('Statistics cache created');
   }
 
-  public async get2HStatistics(req, res) {
+  public async get2HStatistics(req: Request, res: Response) {
     const result = await statistics.$list2H();
     res.send(result);
   }
 
-  public get24HStatistics(req, res) {
+  public get24HStatistics(req: Request, res: Response) {
     res.send(this.cache['24h']);
   }
 
-  public get1WHStatistics(req, res) {
+  public get1WHStatistics(req: Request, res: Response) {
     res.send(this.cache['1w']);
   }
 
-  public get1MStatistics(req, res) {
+  public get1MStatistics(req: Request, res: Response) {
     res.send(this.cache['1m']);
   }
 
-  public get3MStatistics(req, res) {
+  public get3MStatistics(req: Request, res: Response) {
     res.send(this.cache['3m']);
   }
 
-  public get6MStatistics(req, res) {
+  public get6MStatistics(req: Request, res: Response) {
     res.send(this.cache['6m']);
   }
 
-  public get1YStatistics(req, res) {
+  public get1YStatistics(req: Request, res: Response) {
     res.send(this.cache['1y']);
   }
 
-  public async getRecommendedFees(req, res) {
+  public async getRecommendedFees(req: Request, res: Response) {
     const result = feeApi.getRecommendedFee();
     res.send(result);
   }
 
-  public async getMempoolBlocks(req, res) {
+  public getMempoolBlocks(req: Request, res: Response) {
     try {
-      const result = await mempoolBlocks.getMempoolBlocks();
+      const result = mempoolBlocks.getMempoolBlocks();
       res.send(result);
     } catch (e) {
       res.status(500).send(e.message);
     }
   }
 
-  public getTransactionTimes(req, res) {
+  public getTransactionTimes(req: Request, res: Response) {
     if (!Array.isArray(req.query.txId)) {
       res.status(500).send('Not an array');
       return;
     }
-    const txIds = req.query.txId;
+    const txIds: string[] = [];
+    for (const _txId in req.query.txId) {
+      if (typeof req.query.txId[_txId] === 'string') {
+        txIds.push(req.query.txId[_txId].toString());
+      }
+    }
+
     const times = mempool.getFirstSeenForTransactions(txIds);
     res.send(times);
   }
 
-  public getBackendInfo(req, res) {
+  public getBackendInfo(req: Request, res: Response) {
     res.send(backendInfo.getBackendInfo());
   }
 }
diff --git a/frontend/src/app/components/mempool-blocks/mempool-blocks.component.html b/frontend/src/app/components/mempool-blocks/mempool-blocks.component.html
index b0d859abf..00828f356 100644
--- a/frontend/src/app/components/mempool-blocks/mempool-blocks.component.html
+++ b/frontend/src/app/components/mempool-blocks/mempool-blocks.component.html
@@ -9,7 +9,7 @@
           </div>
           <div class="block-size">{{ projectedBlock.blockSize | bytes: 2 }}</div>
           <div class="transaction-count">{{ projectedBlock.nTx | number }} transactions</div>
-          <div class="time-difference" *ngIf="projectedBlock.blockVSize < 1000000">
+          <div class="time-difference" *ngIf="projectedBlock.blockVSize <= 1000000; else mergedBlock">
             <ng-template [ngIf]="network === 'liquid'" [ngIfElse]="timeDiffMainnet">
               In &lt; {{ 1 * i + 1 }} minute
             </ng-template>
@@ -17,8 +17,8 @@
               In ~{{ 10 * i + 10 }} minutes
             </ng-template>
           </div>
-          <ng-template [ngIf]="i === mempoolBlocks.length - 1 && projectedBlock.blockVSize >= 1000000">
-            <div class="time-difference">+{{ projectedBlock.blockVSize / 1000000 | ceil }} blocks</div>
+          <ng-template #mergedBlock>
+            <div class="time-difference"><b>({{ projectedBlock.blockVSize / 1000000 | ceil }} blocks)</b></div>
           </ng-template>
         </div>
         <span class="animated-border"></span>