Picking Rork Max Over FlutterFlow and Replit Agent — Selection Criteria from an Established App Business

Existing Firebase reuse

Firebase Analytics, Firestore, Cloud Functions were already wired. Rork Max code connects through @react-native-firebase/app to the existing project ID without any console reconfiguration:

// rork-generated-feature/services/firebase.ts
import { initializeApp, getApp } from "@react-native-firebase/app";
import firestore from "@react-native-firebase/firestore";
 
// Reuse existing GoogleService-Info.plist / google-services.json
const FIREBASE_PROJECT_ID = "wallpaper-app-prod-2014";
 
async function uploadGeneratedWallpaper(userId: string, imageUri: string): Promise<string> {
  const docRef = await firestore()
    .collection("wallpapers_ugc")
    .add({
      userId,
      imageUri,
      uploadedAt: firestore.FieldValue.serverTimestamp(),
      status: "pending_moderation",
    });
  return docRef.id;
}

FlutterFlow uses a Flutter-side Firebase SDK lineage; getting parity with the existing setup took a day. Replit Agent's web-style integration was less natural.

AdMob mediation — the must-not-break requirement

The existing app monetizes on AdMob mediation (Meta Audience Network, AppLovin, Unity Ads). eCPM optimization is the core of the business. New features must not disturb this wiring.

Rork Max lets generated code call into existing native AdMob modules directly:

// rork-generated/services/admob.ts
import { NativeModules } from "react-native";
 
const { LegacyAdMobBridge } = NativeModules;
 
async function showRewardedAdForGeneration(): Promise<boolean> {
  // Calls into the existing native AdMob mediation setup unchanged
  const reward = await LegacyAdMobBridge.showRewarded("rv_ai_wallpaper_unlock");
  return reward.rewarded === true;
}

Two days for the bridge. FlutterFlow's Flutter AdMob plugin lives in a different lineage from the existing native setup, so I needed a Method Channel + native rewrapping (five days). Replit Agent's web-centric output never produced a workable native ad integration in seven days, so I treated it as not viable for this use case.

Store-review risk — the part many comparisons skip

The most consequential difference was first-pass App Store / Google Play approval. AI-generated code can superficially work while quietly missing review-policy details. I paid extra attention to App Tracking Transparency (iOS) and Data Safety (Android):

• Rork Max: first-pass approval on both iOS and Android
• FlutterFlow: first-pass approval on both (Flutter's ecosystem has matured around store policies)
• Replit Agent: rejected on iOS Guideline 2.1 / 5.1.1, approved on the third submission

The Replit rejection was for sending a user identifier before the ATT consent prompt — fixable, but two weeks of clock time evaporated debugging it. That alone disqualified Replit for this engagement.

Cost shape over time

For long-running apps the shape of the monthly bill matters as much as the level.

• Rork Max: roughly $30/month total ($20 plan + ~$10 usage), steady
• FlutterFlow: $30/month flat (with generation-count caps)
• Replit Agent: $40/month and bursty in heavy-agent months

Once the feature ships and the app moves into maintenance, AI builder usage drops. Predictable fixed cost is a meaningful tiebreaker. Rork Max's flat-ish bill won that axis.

Coexisting with the existing native codebase

This is what tipped the decision. My Android codebase has been growing in Kotlin and Java since 2014. Rebuilding it is not on the table. New features must layer onto the existing Activity stack:

// existing Android code (MainActivity.kt)
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
 
        findViewById<Button>(R.id.btn_ai_wallpaper).setOnClickListener {
            // Launch the Rork-generated React Native feature
            val intent = Intent(this, RorkGeneratedFeatureActivity::class.java)
            startActivityForResult(intent, REQUEST_AI_WALLPAPER)
        }
    }
}

Existing launch flow, existing billing flow, existing ad flow — all preserved, with the new feature dropped in as a React Native Activity. FlutterFlow can technically do an embedded Flutter module, but memory and APK-size overhead at 50M-DL scale make the trade-off less favorable.

Recommended decision rubric for existing app businesses

Three things I now ask before picking an AI app builder for an existing business:

First, run a real proof-of-concept proving the tool can coexist with your existing native ad, billing, and analytics libraries — not just claim it does.

Second, treat first-pass store approval rate as a primary selection metric. A rejection is a 2–3 week loss; small differences in MVP speed will not outweigh that.

Third, model the maintenance-phase cost, not just the build-phase cost. Predictable fixed monthly cost is more valuable than a small unit-price advantage that scales with usage.

By those three, Rork Max was the most consistent choice for my situation.

Three weeks of production data after shipping

Quick early signals from the live feature:

• Day 7 retention on user-generated wallpapers is +12% over the existing curated content
• App-wide crash rate is unchanged; React Native-attributed crashes stay under 0.02%
• AdMob revenue from the new feature's rewarded-ad slot is running about +$340/month
• Rork Max monthly bill has held between $28 and $32

If you are starting from zero, your rubric should differ — FlutterFlow's mature Flutter ecosystem and Replit Agent's web-side integrations both shine in other contexts. For grafting onto a long-running native app business, Rork Max was the right pick for me. Hopefully sharing the rubric helps other operators in a similar position make a faster, less expensive call.