diff --git a/frontend/mempool-frontend-config.sample.json b/frontend/mempool-frontend-config.sample.json
index 5c0f92acf..dd94c29ec 100644
--- a/frontend/mempool-frontend-config.sample.json
+++ b/frontend/mempool-frontend-config.sample.json
@@ -20,5 +20,7 @@
   "MAINNET_BLOCK_AUDIT_START_HEIGHT": 0,
   "TESTNET_BLOCK_AUDIT_START_HEIGHT": 0,
   "SIGNET_BLOCK_AUDIT_START_HEIGHT": 0,
-  "LIGHTNING": false
+  "LIGHTNING": false,
+  "FULL_RBF_ENABLED": false,
+  "ALT_BACKEND_URL": "https://rbf.mempool.space"
 }
diff --git a/frontend/src/app/components/transaction/transaction.component.html b/frontend/src/app/components/transaction/transaction.component.html
index b85f1cd24..ea99ff1f5 100644
--- a/frontend/src/app/components/transaction/transaction.component.html
+++ b/frontend/src/app/components/transaction/transaction.component.html
@@ -1,6 +1,13 @@
 <div class="container-xl">
-
   <div class="title-block">
+    <div *ngIf="fullRBF && notFound && altTx && !replaced" class="alert alert-mempool" role="alert">
+      <span i18n="transaction.rbf.only-default-mempool">This transaction cannot be found in the Full RBF mempool. It may depend on an ancestor which has been replaced by fee.</span>
+    </div>
+
+    <div *ngIf="!fullRBF && notFound && altTx && !replaced" class="alert alert-mempool" role="alert">
+      <span i18n="transaction.rbf.only-full-rbf-mempool">This transaction cannot be found in the default mempool. It may replace a transaction which does not opt-in to replace-by-fee.</span>
+    </div>
+
     <div *ngIf="rbfTransaction" class="alert alert-mempool" role="alert">
       <span i18n="transaction.rbf.replacement|RBF replacement">This transaction has been replaced by:</span>
       <app-truncate [text]="rbfTransaction.txid" [lastChars]="12" [link]="['/tx/' | relativeUrl, rbfTransaction.txid]"></app-truncate>
@@ -101,7 +108,7 @@
           <div class="col-sm">
             <table class="table table-borderless table-striped">
               <tbody>
-                <ng-template [ngIf]="transactionTime !== 0 && !replaced">
+                <ng-template [ngIf]="transactionTime !== 0 && !notFound">
                   <tr *ngIf="transactionTime === -1; else firstSeenTmpl">
                     <td><span class="skeleton-loader"></span></td>
                     <td><span class="skeleton-loader"></span></td>
@@ -113,7 +120,7 @@
                     </tr>
                   </ng-template>
                 </ng-template>
-                <tr *ngIf="!replaced">
+                <tr *ngIf="!notFound">
                   <td class="td-width" i18n="transaction.eta|Transaction ETA">ETA</td>
                   <td>
                     <ng-template [ngIf]="txInBlockIndex === undefined" [ngIfElse]="estimationTmpl">
diff --git a/frontend/src/app/components/transaction/transaction.component.ts b/frontend/src/app/components/transaction/transaction.component.ts
index 7e1ae525e..6e39cbacd 100644
--- a/frontend/src/app/components/transaction/transaction.component.ts
+++ b/frontend/src/app/components/transaction/transaction.component.ts
@@ -1,5 +1,6 @@
 import { Component, OnInit, AfterViewInit, OnDestroy, HostListener, ViewChild, ElementRef } from '@angular/core';
 import { ElectrsApiService } from '../../services/electrs-api.service';
+import { AltElectrsApiService } from '../../services/alt-electrs-api.service';
 import { ActivatedRoute, ParamMap, Router } from '@angular/router';
 import {
   switchMap,
@@ -43,6 +44,7 @@ export class TransactionComponent implements OnInit, AfterViewInit, OnDestroy {
   fetchRbfSubscription: Subscription;
   fetchCachedTxSubscription: Subscription;
   txReplacedSubscription: Subscription;
+  altBackendTxSubscription: Subscription;
   blocksSubscription: Subscription;
   queryParamsSubscription: Subscription;
   urlFragmentSubscription: Subscription;
@@ -55,6 +57,7 @@ export class TransactionComponent implements OnInit, AfterViewInit, OnDestroy {
   fetchCpfp$ = new Subject<string>();
   fetchRbfHistory$ = new Subject<string>();
   fetchCachedTx$ = new Subject<string>();
+  checkAltBackend$ = new Subject<string>();
   now = new Date().getTime();
   timeAvg$: Observable<number>;
   liquidUnblinding = new LiquidUnblinding();
@@ -69,6 +72,10 @@ export class TransactionComponent implements OnInit, AfterViewInit, OnDestroy {
   hideFlow: boolean = this.stateService.hideFlow.value;
   overrideFlowPreference: boolean = null;
   flowEnabled: boolean;
+  notFound: boolean = false;
+  altTx: Transaction;
+  fullRBF: boolean = false;
+  altBackend: string;
 
   tooltipPosition: { x: number, y: number };
 
@@ -80,13 +87,17 @@ export class TransactionComponent implements OnInit, AfterViewInit, OnDestroy {
     private router: Router,
     private relativeUrlPipe: RelativeUrlPipe,
     private electrsApiService: ElectrsApiService,
+    private altElectrsApiService: AltElectrsApiService,
     private stateService: StateService,
     private cacheService: CacheService,
     private websocketService: WebsocketService,
     private audioService: AudioService,
     private apiService: ApiService,
     private seoService: SeoService
-  ) {}
+  ) {
+    this.fullRBF = stateService.env.FULL_RBF_ENABLED;
+    this.altBackend = stateService.env.ALT_BACKEND_URL;
+  }
 
   ngOnInit() {
     this.websocketService.want(['blocks', 'mempool-blocks']);
@@ -208,6 +219,38 @@ export class TransactionComponent implements OnInit, AfterViewInit, OnDestroy {
       }
     });
 
+    this.altBackendTxSubscription = this.checkAltBackend$
+    .pipe(
+      switchMap((txId) =>
+        this.altElectrsApiService
+          .getTransaction$(txId)
+          .pipe(
+            catchError((e) => {
+              return of(null);
+            })
+          )
+      )
+    ).subscribe((tx) => {
+      if (!tx) {
+        this.altTx = null;
+        return;
+      }
+
+      this.altTx = tx;
+      if (tx.fee === undefined) {
+        this.altTx.fee = 0;
+      }
+      this.altTx.feePerVsize = tx.fee / (tx.weight / 4);
+      if (!this.tx) {
+        this.tx = tx;
+        this.isLoadingTx = false;
+        this.error = undefined;
+        this.waitingForTransaction = false;
+        this.graphExpanded = false;
+        this.setupGraph();
+      }
+    });
+
     this.subscription = this.route.paramMap
       .pipe(
         switchMap((params: ParamMap) => {
@@ -282,8 +325,13 @@ export class TransactionComponent implements OnInit, AfterViewInit, OnDestroy {
       )
       .subscribe((tx: Transaction) => {
           if (!tx) {
+            this.notFound = true;
+            if (this.stateService.env.ALT_BACKEND_URL) {
+              this.checkAltBackend$.next(this.txId);
+            }
             return;
           }
+          this.notFound = false;
 
           this.tx = tx;
           if (tx.fee === undefined) {
@@ -322,6 +370,9 @@ export class TransactionComponent implements OnInit, AfterViewInit, OnDestroy {
               this.fetchCpfp$.next(this.tx.txid);
             }
             this.fetchRbfHistory$.next(this.tx.txid);
+            if (this.stateService.env.ALT_BACKEND_URL) {
+              this.checkAltBackend$.next(this.txId);
+            }
           }
           setTimeout(() => { this.applyFragment(); }, 0);
         },
@@ -423,6 +474,8 @@ export class TransactionComponent implements OnInit, AfterViewInit, OnDestroy {
     this.isLoadingTx = true;
     this.rbfTransaction = undefined;
     this.replaced = false;
+    this.altTx = null;
+    this.notFound = false;
     this.transactionTime = -1;
     this.cpfpInfo = null;
     this.rbfReplaces = [];
@@ -493,6 +546,7 @@ export class TransactionComponent implements OnInit, AfterViewInit, OnDestroy {
     this.fetchCpfpSubscription.unsubscribe();
     this.fetchRbfSubscription.unsubscribe();
     this.fetchCachedTxSubscription.unsubscribe();
+    this.altBackendTxSubscription?.unsubscribe();
     this.txReplacedSubscription.unsubscribe();
     this.blocksSubscription.unsubscribe();
     this.queryParamsSubscription.unsubscribe();
diff --git a/frontend/src/app/services/alt-electrs-api.service.ts b/frontend/src/app/services/alt-electrs-api.service.ts
new file mode 100644
index 000000000..fdb5e046e
--- /dev/null
+++ b/frontend/src/app/services/alt-electrs-api.service.ts
@@ -0,0 +1,91 @@
+import { Injectable } from '@angular/core';
+import { HttpClient } from '@angular/common/http';
+import { Observable } from 'rxjs';
+import { Transaction, Address, Outspend, Recent, Asset } from '../interfaces/electrs.interface';
+import { StateService } from './state.service';
+import { BlockExtended } from '../interfaces/node-api.interface';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class AltElectrsApiService {
+  private apiBaseUrl: string; // base URL is protocol, hostname, and port
+  private apiBasePath: string; // network path is /testnet, etc. or '' for mainnet
+
+  constructor(
+    private httpClient: HttpClient,
+    private stateService: StateService,
+  ) {
+    this.apiBaseUrl = stateService.env.ALT_BACKEND_URL || '';
+    this.apiBasePath = ''; // assume mainnet by default
+    this.stateService.networkChanged$.subscribe((network) => {
+      if (network === 'bisq') {
+        network = '';
+      }
+      this.apiBasePath = network ? '/' + network : '';
+    });
+  }
+
+  getBlock$(hash: string): Observable<BlockExtended> {
+    return this.httpClient.get<BlockExtended>(this.apiBaseUrl + this.apiBasePath + '/api/block/' + hash);
+  }
+
+  listBlocks$(height?: number): Observable<BlockExtended[]> {
+    return this.httpClient.get<BlockExtended[]>(this.apiBaseUrl + this.apiBasePath + '/api/blocks/' + (height || ''));
+  }
+
+  getTransaction$(txId: string): Observable<Transaction> {
+    return this.httpClient.get<Transaction>(this.apiBaseUrl + this.apiBasePath + '/api/tx/' + txId);
+  }
+
+  getRecentTransaction$(): Observable<Recent[]> {
+    return this.httpClient.get<Recent[]>(this.apiBaseUrl + this.apiBasePath + '/api/mempool/recent');
+  }
+
+  getOutspend$(hash: string, vout: number): Observable<Outspend> {
+    return this.httpClient.get<Outspend>(this.apiBaseUrl + this.apiBasePath + '/api/tx/' + hash + '/outspend/' + vout);
+  }
+
+  getOutspends$(hash: string): Observable<Outspend[]> {
+    return this.httpClient.get<Outspend[]>(this.apiBaseUrl + this.apiBasePath + '/api/tx/' + hash + '/outspends');
+  }
+
+  getBlockTransactions$(hash: string, index: number = 0): Observable<Transaction[]> {
+    return this.httpClient.get<Transaction[]>(this.apiBaseUrl + this.apiBasePath + '/api/block/' + hash + '/txs/' + index);
+  }
+
+  getBlockHashFromHeight$(height: number): Observable<string> {
+    return this.httpClient.get(this.apiBaseUrl + this.apiBasePath + '/api/block-height/' + height, {responseType: 'text'});
+  }
+
+  getAddress$(address: string): Observable<Address> {
+    return this.httpClient.get<Address>(this.apiBaseUrl + this.apiBasePath + '/api/address/' + address);
+  }
+
+  getAddressTransactions$(address: string): Observable<Transaction[]> {
+    return this.httpClient.get<Transaction[]>(this.apiBaseUrl + this.apiBasePath + '/api/address/' + address + '/txs');
+  }
+
+  getAddressTransactionsFromHash$(address: string, txid: string): Observable<Transaction[]> {
+    return this.httpClient.get<Transaction[]>(this.apiBaseUrl + this.apiBasePath + '/api/address/' + address + '/txs/chain/' + txid);
+  }
+
+  getAsset$(assetId: string): Observable<Asset> {
+    return this.httpClient.get<Asset>(this.apiBaseUrl + this.apiBasePath + '/api/asset/' + assetId);
+  }
+
+  getAssetTransactions$(assetId: string): Observable<Transaction[]> {
+    return this.httpClient.get<Transaction[]>(this.apiBaseUrl + this.apiBasePath + '/api/asset/' + assetId + '/txs');
+  }
+
+  getAssetTransactionsFromHash$(assetId: string, txid: string): Observable<Transaction[]> {
+    return this.httpClient.get<Transaction[]>(this.apiBaseUrl + this.apiBasePath + '/api/asset/' + assetId + '/txs/chain/' + txid);
+  }
+
+  getAddressesByPrefix$(prefix: string): Observable<string[]> {
+    if (prefix.toLowerCase().indexOf('bc1') === 0) {
+      prefix = prefix.toLowerCase();
+    }
+    return this.httpClient.get<string[]>(this.apiBaseUrl + this.apiBasePath + '/api/address-prefix/' + prefix);
+  }
+}
diff --git a/frontend/src/app/services/state.service.ts b/frontend/src/app/services/state.service.ts
index 86efa57f8..67fe98d6d 100644
--- a/frontend/src/app/services/state.service.ts
+++ b/frontend/src/app/services/state.service.ts
@@ -42,6 +42,8 @@ export interface Env {
   MAINNET_BLOCK_AUDIT_START_HEIGHT: number;
   TESTNET_BLOCK_AUDIT_START_HEIGHT: number;
   SIGNET_BLOCK_AUDIT_START_HEIGHT: number;
+  FULL_RBF_ENABLED: boolean;
+  ALT_BACKEND_URL: string;
 }
 
 const defaultEnv: Env = {
@@ -70,6 +72,8 @@ const defaultEnv: Env = {
   'MAINNET_BLOCK_AUDIT_START_HEIGHT': 0,
   'TESTNET_BLOCK_AUDIT_START_HEIGHT': 0,
   'SIGNET_BLOCK_AUDIT_START_HEIGHT': 0,
+  'FULL_RBF_ENABLED': false,
+  'ALT_BACKEND_URL': '',
 };
 
 @Injectable({