diff --git a/backend/src/api/bitcoin/bitcoin.routes.ts b/backend/src/api/bitcoin/bitcoin.routes.ts
index ab5b0a73a..ec63f4ff8 100644
--- a/backend/src/api/bitcoin/bitcoin.routes.ts
+++ b/backend/src/api/bitcoin/bitcoin.routes.ts
@@ -751,13 +751,13 @@ class BitcoinRoutes {
   }
 
   private async $testTransactions(req: Request, res: Response) {
-    res.setHeader('content-type', 'text/plain');
     try {
       const rawTxs = Common.getTransactionsFromRequest(req);
       const maxfeerate = parseFloat(req.query.maxfeerate as string);
       const result = await bitcoinApi.$testMempoolAccept(rawTxs, maxfeerate);
       res.send(result);
     } catch (e: any) {
+      res.setHeader('content-type', 'text/plain');
       res.status(400).send(e.message && e.code ? 'testmempoolaccept RPC error: ' + JSON.stringify({ code: e.code, message: e.message })
         : (e.message || 'Error'));
     }
diff --git a/backend/src/api/common.ts b/backend/src/api/common.ts
index ddbe98ec5..2c9338814 100644
--- a/backend/src/api/common.ts
+++ b/backend/src/api/common.ts
@@ -946,12 +946,16 @@ export class Common {
     return this.validateTransactionHex(matches[1].toLowerCase());
   }
 
-  static getTransactionsFromRequest(req: Request): string[] {
-    if (typeof req.body !== 'string') {
-      throw Object.assign(new Error('Non-string request body'), { code: -1 });
+  static getTransactionsFromRequest(req: Request, limit: number = 25): string[] {
+    if (!Array.isArray(req.body) || req.body.some(hex => typeof hex !== 'string')) {
+      throw Object.assign(new Error('Invalid request body (should be an array of hexadecimal strings)'), { code: -1 });
     }
 
-    const txs = req.body.split(',');
+    if (limit && req.body.length > limit) {
+      throw Object.assign(new Error('Exceeded maximum of 25 transactions'), { code: -1 });
+    }
+
+    const txs = req.body;
 
     return txs.map(rawTx => {
       // Support both upper and lower case hex
diff --git a/backend/src/index.ts b/backend/src/index.ts
index b088155ea..df9f7dc65 100644
--- a/backend/src/index.ts
+++ b/backend/src/index.ts
@@ -131,6 +131,7 @@ class Server {
       })
       .use(express.urlencoded({ extended: true }))
       .use(express.text({ type: ['text/plain', 'application/base64'] }))
+      .use(express.json())
       ;
 
     if (config.DATABASE.ENABLED && config.FIAT_PRICE.ENABLED) {
diff --git a/frontend/src/app/components/test-transactions/test-transactions.component.scss b/frontend/src/app/components/test-transactions/test-transactions.component.scss
index 399575b8e..ffdd5811b 100644
--- a/frontend/src/app/components/test-transactions/test-transactions.component.scss
+++ b/frontend/src/app/components/test-transactions/test-transactions.component.scss
@@ -2,6 +2,7 @@
   td, th {
     &.allowed {
       width: 10%;
+      text-align: center;
     }
     &.txid {
       width: 50%;
diff --git a/frontend/src/app/components/test-transactions/test-transactions.component.ts b/frontend/src/app/components/test-transactions/test-transactions.component.ts
index c959cb2b0..7291dae20 100644
--- a/frontend/src/app/components/test-transactions/test-transactions.component.ts
+++ b/frontend/src/app/components/test-transactions/test-transactions.component.ts
@@ -37,6 +37,21 @@ export class TestTransactionsComponent implements OnInit {
   }
 
   testTxs() {
+    let txs: string[] = [];
+    try {
+      txs = (this.testTxsForm.get('txs')?.value as string).split(',').map(hex => hex.trim());
+      if (!txs?.length) {
+        this.error = 'At least one transaction is required';
+        return;
+      } else if (txs.length > 25) {
+        this.error = 'Exceeded maximum of 25 transactions';
+        return;
+      }
+    } catch (e) {
+      this.error = e?.message;
+      return;
+    }
+
     let maxfeerate;
     this.invalidMaxfeerate = false;
     try {
@@ -51,7 +66,7 @@ export class TestTransactionsComponent implements OnInit {
     this.isLoading = true;
     this.error = '';
     this.results = [];
-    this.apiService.testTransactions$((this.testTxsForm.get('txs')?.value as string).split(',').map(hex => hex.trim()).join(','), maxfeerate === 0.1 ? null : maxfeerate)
+    this.apiService.testTransactions$(txs, maxfeerate === 0.1 ? null : maxfeerate)
       .subscribe((result) => {
         this.isLoading = false;
         this.results = result || [];
diff --git a/frontend/src/app/services/api.service.ts b/frontend/src/app/services/api.service.ts
index e41f8eb9e..0531916a0 100644
--- a/frontend/src/app/services/api.service.ts
+++ b/frontend/src/app/services/api.service.ts
@@ -238,8 +238,8 @@ export class ApiService {
     return this.httpClient.post<any>(this.apiBaseUrl + this.apiBasePath + '/api/tx', hexPayload, { responseType: 'text' as 'json'});
   }
 
-  testTransactions$(hexPayload: string, maxfeerate?: number): Observable<TestMempoolAcceptResult[]> {
-    return this.httpClient.post<TestMempoolAcceptResult[]>(this.apiBaseUrl + this.apiBasePath + `/api/txs/test${maxfeerate != null ? '?maxfeerate=' + maxfeerate.toFixed(8) : ''}`, hexPayload);
+  testTransactions$(rawTxs: string[], maxfeerate?: number): Observable<TestMempoolAcceptResult[]> {
+    return this.httpClient.post<TestMempoolAcceptResult[]>(this.apiBaseUrl + this.apiBasePath + `/api/txs/test${maxfeerate != null ? '?maxfeerate=' + maxfeerate.toFixed(8) : ''}`, rawTxs);
   }
 
   getTransactionStatus$(txid: string): Observable<any> {