Car Booking SaaS – Android Apps Documentation

Overview

Car Booking is a pair of Android apps for the Car Booking SaaS – Car Rental Management System website: a Driver app for drivers and a Customer app for renters. Rental company owners and staff keep using the website. The apps talk only to your website, so all data stays on your server.

What is in the package

Features

Driver app

Customer app

Not included

• Paying by card inside the app (payment opens the company's own secure page, so card data never passes through the app).
• Saved cards and in-app language packs.

Requirements

Your computer (to build the apps)

Phones that can run the apps

Android 7.0 or newer (the minimum is Flutter's default for the Flutter version you build with).

Accounts

Website

Car Booking SaaS v1.7 or newer on HTTPS — see Prepare the website.

Install Flutter & Android Studio

1. Install Android Studio from developer.android.com/studio. Start it once and finish the setup wizard (Standard). Then open Settings → Languages & Frameworks → Android SDK → SDK Tools and tick Android SDK Command-line Tools and Android SDK Platform-Tools. In Plugins, install the Flutter plugin (it adds Dart).
2. Install Flutter following docs.flutter.dev/get-started/install (choose your operating system → Android). Unzip it to a folder without spaces (e.g. C:\src\flutter or ~/flutter) and add its bin folder to your PATH.
3. Accept the Android licences and check everything:

   flutter doctor --android-licenses
   flutter doctor

   flutter doctor must show a tick for Flutter and Android toolchain. (Chrome, Xcode and Visual Studio are not needed for Android.)

Prepare the website

Do this once on the website before building the apps.

1. Website on HTTPS. Install Car Booking SaaS v1.7 or newer on your domain with an SSL certificate (Let's Encrypt is free). Release builds of the apps refuse plain http://.
2. Run the update. If you upgraded an existing website, make sure the database update ran (php artisan migrate --force, or the website's update screen). It creates the tables for phones, notifications, customer sign-in codes and photos.
3. Find your API address. It is your website address followed by /api/mobile/v1, for example https://rent.yourdomain.com/api/mobile/v1. Test it in a browser: https://rent.yourdomain.com/api/mobile/v1/companies?q=a should answer with JSON (a list of companies), and …/api/mobile/v1/company/demo shows one company's name, logo and colour.
4. Online booking for each company. The customer app needs the company's online booking switched on (owner → Online Booking). The company code is the web address name of that page: …/book/demo means code demo. Owners also find the code, a QR code and a "copy message" button under Mobile apps in their menu.
5. Customer sign-in. Customers receive a 6-digit code by email, so the company needs working email settings (Settings → Email). The owner can also allow password sign-in and SMS code sign-in (needs the owner's Twilio account). Each method can be switched on or off by the company.
6. Driver accounts. Create each driver under Driver in the owner's menu. Drivers sign in to the app with that email and password. Set the commission rule on the driver's page to see earnings in the app.
7. Store links (optional but recommended). After publishing, add the Google Play / App Store links as super admin → Mobile apps. They appear on every company's public "Get our app" page (/book/<code>/app) together with the QR code.
8. Cron job and queue. The website's cron (php artisan schedule:run every minute) sends the reminders (pick-up, return, payment). For push notifications keep a queue worker running (php artisan queue:work) or set QUEUE_CONNECTION=sync in .env.
9. Upload size. Photos are sent from the phone: set PHP upload_max_filesize and post_max_size to at least 10M.

Set up the projects

Unlike many Flutter packages, the android/ folder of both apps is already included, with the permissions, app name, icon and Firebase hook applied. There is no setup script.

1. Unzip the package. It contains driver_app, customer_app and docs; put them in a path without spaces, for example ~/projects/android_app.
2. Download the libraries for each app:

   cd ~/projects/android_app/driver_app
   flutter pub get
   cd ../customer_app
   flutter pub get

3. Set your website address. Either edit lib/config.dart in each app:

   static const String apiBase = String.fromEnvironment(
     'API_BASE',
     defaultValue: 'https://your-domain.com/api/mobile/v1',
   );

   or leave the file as it is and add --dart-define=API_BASE=https://your-domain.com/api/mobile/v1 to every flutter run / flutter build command.
4. Choose your package name. The placeholders are com.carbooking.driver_app and com.carbooking.customer_app. Change them to your own (for example com.acmerentals.driver) before you publish: in android/app/build.gradle.kts (namespace and applicationId) and rename the folder android/app/src/main/kotlin/com/carbooking/driver_app (and the package line in MainActivity.kt) to match.
   The package name can never change after the app is published on Google Play. Use lower case letters, numbers, underscores and dots only.
5. Open the project in Android Studio (File → Open → the driver_app or customer_app folder) or VS Code.

Run on a phone or emulator

On a real phone

1. On the phone: Settings → About phone, tap Build number 7 times to enable Developer options.
2. Settings → Developer options → USB debugging: on. Connect the phone with USB and allow the computer.
3. Check the phone is listed, then run (in the app's folder):

   flutter devices
   flutter run --dart-define=API_BASE=https://your-domain.com/api/mobile/v1

On the emulator

Android Studio → Device Manager → Create device (e.g. Pixel 8, latest system image) → Start. Then flutter run.

Testing against a local website (http)

Debug builds allow plain http:// so you can test against a website on your computer or local network (release builds need HTTPS):

# phone on the same Wi-Fi as your computer (use your computer's IP address)
flutter run --dart-define=API_BASE=http://192.168.1.10/car-booking-saas/main_file/api/mobile/v1

# Android emulator: 10.0.2.2 is your computer
flutter run --dart-define=API_BASE=http://10.0.2.2/car-booking-saas/main_file/api/mobile/v1

Which account to sign in with

A test APK to share

flutter build apk --debug --dart-define=API_BASE=https://your-domain.com/api/mobile/v1
# file: build/app/outputs/flutter-apk/app-debug.apk

Send this file to testers; they install it after allowing "Install unknown apps". For the store, use a release build (next sections).

Branding & customisation

Changes that need no new build (from the website)

Changes in the code (then build again)

Push notifications (Firebase)

Without this step the apps work and show updates in the inbox, but phones do not get pop-up notifications. Push needs a Firebase project, one file in each app, and one file on the website server.

1. Go to console.firebase.google.com → Create a project (Google Analytics is not needed).
2. In the project: Add app → Android, once per app. Android package name: exactly your app ID (applicationId in android/app/build.gradle.kts), for example com.acmerentals.driver and com.acmerentals.customer. SHA-1 is not needed. Click Register app.
3. Download google-services.json and put it in the app's android/app/ folder. The build picks it up automatically (the Firebase plugin is only switched on when this file exists). Do this for both apps, each with its own file.
4. Firebase → Project settings → Service accounts → Generate new private key. A JSON file downloads. Keep it secret.
5. Server: save that JSON file on the website server outside the web folder and put its path in the website's .env:

   FCM_CREDENTIALS=/home/youruser/firebase-service-account.json

   Keep the queue running (php artisan queue:work) or use QUEUE_CONNECTION=sync.
6. Rebuild the apps, install them on a real phone (push does not work on most emulators), sign in and allow notifications when Android asks (Android 13+).
7. Test: in the admin panel assign the driver a job. The driver's phone should ring within a few seconds. For the customer app confirm a booking of that customer.

When users are notified

Every message to a customer is also saved in the in-app inbox (the bell), even when phone notifications are off. The company switches push messages on or off under Configuration → Email Notification (the Push Enable column for driver job alerts and the Phone app notifications card for customer booking updates).

Version numbers

The version of each app is in its pubspec.yaml:

version: 1.0.0+1

• 1.0.0 is the version users see (versionName).
• +1 is the build number (versionCode). Google Play requires a higher number for every upload: 1.0.0+1, 1.0.1+2, 1.1.0+3 …

Signing key (keystore)

Google Play only accepts apps signed with your own upload key. Create it once (one key can sign both apps):

# macOS / Linux
keytool -genkey -v -keystore ~/upload-keystore.jks -keyalg RSA -keysize 2048 -validity 10000 -alias upload

# Windows (PowerShell)
keytool -genkey -v -keystore $env:USERPROFILE\upload-keystore.jks -storetype JKS -keyalg RSA -keysize 2048 -validity 10000 -alias upload

keytool comes with Java; if it is not found, use the one in Android Studio's jbr/bin folder. Choose a strong password and answer the questions (name, organisation, country).

Tell the build where the key is

In each app create android/key.properties:

storePassword=your-store-password
keyPassword=your-key-password
keyAlias=upload
storeFile=/home/you/upload-keystore.jks

(Windows: storeFile=C:\\Users\\you\\upload-keystore.jks.) Add android/key.properties to .gitignore.

Edit android/app/build.gradle.kts. At the top, after the plugins { … } block:

import java.util.Properties
import java.io.FileInputStream

val keystoreProperties = Properties()
val keystorePropertiesFile = rootProject.file("key.properties")
if (keystorePropertiesFile.exists()) {
    keystoreProperties.load(FileInputStream(keystorePropertiesFile))
}

Inside android { … }, before buildTypes, add a signing config, and use it for release:

    signingConfigs {
        create("release") {
            keyAlias = keystoreProperties["keyAlias"] as String
            keyPassword = keystoreProperties["keyPassword"] as String
            storeFile = keystoreProperties["storeFile"]?.let { file(it) }
            storePassword = keystoreProperties["storePassword"] as String
        }
    }

    buildTypes {
        release {
            signingConfig = signingConfigs.getByName("release")
        }
    }

Replace the existing release { signingConfig = signingConfigs.getByName("debug") } block (it is marked with a TODO) — do not keep both.

Build the release

Make sure the apps point to your https website, then in each app folder:

flutter clean
flutter pub get

# for Google Play (Android App Bundle)
flutter build appbundle --release --dart-define=API_BASE=https://your-domain.com/api/mobile/v1
# file: build/app/outputs/bundle/release/app-release.aab

# optional: an installable APK (direct download, other stores)
flutter build apk --release --dart-define=API_BASE=https://your-domain.com/api/mobile/v1
# file: build/app/outputs/flutter-apk/app-release.apk

If you set the address in lib/config.dart, the --dart-define part can be left out.

Test the release APK on a real phone before uploading (flutter install or copy the APK): sign in, open each screen, take a photo, create a test booking and send a test notification.

Publish on Google Play

Publish the Driver app and the Customer app as two separate store listings.

1. Developer account

Register at play.google.com/console ($25 one time, identity verification).

• Organisation account (needs a free D-U-N-S number for your company): can publish to production directly.
• Personal account: Google requires a closed test with at least 12 testers for 14 days in a row before you can apply for production. Plan for this.

2. Create the app

Play Console → Create app: app name, default language, App (not game), Free, accept the declarations. Do this once for each app.

3. Store listing (Grow → Store presence → Main store listing)

Tip: take screenshots on the emulator (camera button in the emulator toolbar) with demo data on your website.

4. App content (Policy → App content)

5. Upload and release

1. Testing → Internal testing → Create release → accept Play App Signing → upload app-release.aab → release notes → Save → Review → Start rollout. Add your testers' emails and install through the opt-in link.
2. Closed testing (required for new personal accounts: 12+ testers, 14 days).
3. Production → Create release → upload (or promote the tested release) → choose countries → Send for review.
4. Review usually takes from a few hours to 7 days. You get an email when the app is live.
5. Then add the store links on the website: super admin → Mobile apps.

Updates

Raise the build number in pubspec.yaml, build a new .aab, and create a new release in Production (or a testing track first). Use staged rollout (e.g. 20 %) for big changes.

Other distribution

The release APK (app-release.apk) can also be offered as a direct download from your website, through an MDM, or on other stores (Amazon Appstore, Samsung Galaxy Store, Huawei AppGallery). Push notifications need Google Play services on the phone (not available on Huawei phones without Google services).

Privacy & data safety

Both stores require a privacy policy URL and a description of the data the apps handle. Publish a privacy policy page on your website (the website's own privacy policy page can be used) and use these answers in Play Console → Data safety:

• Data is encrypted in transit (HTTPS).
• Data is not sold or shared with third parties for advertising.

Android permissions used

Android settings reference

What is already set in the android/ folder of the apps, for reference or when you change something by hand.

android/app/src/main/AndroidManifest.xml

<manifest ...>
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.CAMERA"/>
    <!-- customer app only -->
    <uses-permission android:name="android.permission.USE_BIOMETRIC"/>
    <application android:label="Car Booking" ...> ... </application>
    <queries>
        <intent><action android:name="android.intent.action.VIEW"/><data android:scheme="https"/></intent>
        <intent><action android:name="android.intent.action.DIAL"/><data android:scheme="tel"/></intent>
        <intent><action android:name="android.intent.action.SENDTO"/><data android:scheme="mailto"/></intent>
    </queries>
</manifest>

android/app/src/debug/AndroidManifest.xml (debug builds only)

<application android:usesCleartextTraffic="true"/>

This is why http:// works while testing but not in release builds.

android/app/build.gradle.kts (Firebase)

// Firebase push: switched on by dropping your google-services.json into android/app/
if (file("google-services.json").exists()) {
    apply(plugin = "com.google.gms.google-services")
}

Code structure

Both apps

Driver app screens (lib/screens/)

login, home, dashboard, jobs, job_detail, agreements, expenses, earnings, more.

Customer app screens (lib/screens/)

company and scan_code (find a company), login, home, dashboard, cars, car_detail, bookings, booking_detail, booking_photos, documents, rewards, profile, contact, assistant (AI helper), notifications, switch_company. Extra files: app_lock.dart (fingerprint / face / PIN), favorites.dart, cars_filter.dart, settings.dart.

Libraries used: Driver — http, flutter_secure_storage, image_picker, url_launcher, intl, firebase_core, firebase_messaging. Customer — the same plus local_auth (app lock) and mobile_scanner (QR codes). No analytics or advertising libraries.

To add a screen: create it in lib/screens/, load data with the client in lib/api.dart, and add the endpoint on the website in routes/api.php (every endpoint is described in docs/mobile-api.md).

Own-brand customer app

By default the customer app is one app for many companies: the renter finds a company by name, QR code or code. A rental company that wants its own app (its own name, icon and store listing, with no company search) can have a copy built just for it.

From the customer_app folder (needs Python 3 with Pillow: pip install pillow, and Flutter on the PATH for --build):

python3 tools/build_branded.py \
  --company sunrentals \
  --name "Sun Rentals" \
  --logo logo.png \
  --api https://your-domain.com/api/mobile/v1 \
  --package com.sunrentals.app \
  --build apk

The result is a copy of the app in build_branded/<company>/. The original is never changed. A company can add its own store links under Mobile apps in its menu; they replace the platform's links on that company's website.

Updating to a new version

When a new version of the apps is released:

1. Back up your project folders (driver_app and customer_app), especially your android/ edits (signing, google-services.json), lib/config.dart and assets/.
2. Update the website first if the release notes say the apps need a newer website version.
3. Copy the new lib/, pubspec.yaml, test/ and docs/ over your project. Put your own values back into lib/config.dart (or keep using --dart-define=API_BASE=…, which needs no edit).
4. Run flutter pub get.
5. Raise the version in pubspec.yaml (see "Version numbers"), build and upload as usual.

Troubleshooting

FAQ

Do I need one app per rental company?

No. One customer app serves all companies on your website: renters find the company by name, QR code or code. A company that wants its own listing can have an own-brand build (Own-brand customer app).

Can owners and staff use the apps?

Not in this version. Owners, managers and staff use the website, which is fully mobile friendly. The apps are for drivers and customers.

Where is the data stored?

Only on your website/server. The phone keeps the sign-in token (in secure storage) and a few settings such as saved favourites.

Does the app work without the website?

No, every screen loads from your website's API.

Can I change the server address without a new build?

No, the address is built into the app (API_BASE). Company name, logo and colours are not built in: they come from the website.

How do payments work?

Pay now opens the company's secure payment page in the browser (Stripe, PayPal, Paystack, Flutterwave or Razorpay); card data never passes through the app.

Can I publish the apps under my own name?

Yes — your package name, app name, icon and Google Play developer account.

Do I need a Mac?

No, Android apps build on Windows, macOS and Linux. (The iPhone apps need a Mac, see the iPhone guide.)

Can I give testers the app before it is on Google Play?

Yes: Play Console internal testing, or share an APK.

Can customers delete their account?

Yes: Profile → Delete my account in the customer app.

Support & changelog

Before contacting support, please check the Troubleshooting section and run flutter doctor.

When you contact support, include:

• Your purchase code
• App version (pubspec.yaml) and website version
• Output of flutter doctor -v
• The exact error message or a screenshot
• What you did just before the problem

Support covers installation questions, bugs and help with the steps in this guide. Customisations (new features, design changes) are not included in support but can be ordered separately. Create a support ticket here.

Changelog