SubZero - Offline Subscription Manager and Expense Tracker

SubZero is a premium Flutter subscription tracker app template for Android and iOS. It brings together a subscription dashboard with a single monthly total, spending analytics by category, bill reminders before every renewal, and 25 quick-add templates for services like Netflix, Spotify and Adobe Creative Cloud. Use it to launch a subscription manager, a recurring bills tracker or a personal budgeting app, all from one ready-to-publish codebase.

Version 1.5.0 adds AppConfig, one file that holds the app name, tagline, company, support email, version, file prefix and brand colours, so rebranding starts in a single place. It builds on 1.4.0, which added Google UMP consent, reliable reminders and a backup restore fix.

Offline-first and private: SubZero has no login, no backend server and no bank connection. Subscriptions, settings and the PIN are stored on the device with Hive, so there is no hosting bill to pay each month.

Web Live Preview
Quick Setup Guide
Complete Setup Guide

Demo instructions: there is no login, email or password. Open the Web Live Preview and the app starts with sample subscriptions. To try the lock screen, enable Settings > App Lock and choose any 4-digit PIN; it is stored only in your browser. Reminders, backup and restore, the PDF report and ads run in the Android and iOS builds, not in the web preview.

Core Features of the SubZero Flutter App Template

1. Subscription Dashboard with a Monthly Spend Total

The dashboard lists every subscription and shows one total monthly spend on a card at the top. Yearly plans are converted to a monthly amount, so users see their real monthly cost at a glance.

• Monthly and yearly billing cycles for every subscription.
• Six sort options: name A-Z or Z-A, price high to low or low to high, and date newest or oldest first.
• Add, edit and delete subscriptions, with a colour, category, price, first billing date and optional cancel link.
• One-tap PDF report: a subscription report with the total monthly spend, the number of active services and a table of every subscription, opened in the system print and save dialog.
• Billing dates roll forward automatically after each cycle.

2. Spending Analytics and Upcoming Bills

A donut chart shows where the money goes, and the Upcoming Bills screen counts down to each renewal so nothing renews by surprise.

• Category spending chart built with fl_chart, showing the share and monthly amount for each category.
• 6 categories: Entertainment, Work, Utilities, Personal, Shopping and Other.
• Upcoming Bills with the next billing date and days left, colour-coded by urgency.
• Bill reminders one day before each renewal at 9:00 AM local time. The next 3 renewals are scheduled on Android (1 on iOS), and reminders are rescheduled on start, on resume and after a restore.
• Reminders are cancelled when a subscription is deleted, when all data is cleared or when Billing Reminders is switched off.

3. 25 Quick-Add Subscription Templates

Users add popular services in one tap. Each template fills in the name, a default price, the category, a brand colour and a link to the provider’s cancel page.

• 25 templates: Netflix, Disney+, Hulu, HBO Max, YouTube Premium, Amazon Prime, Twitch, Apple TV+, Spotify, Apple Music, Audible, SoundCloud Go, Microsoft 365, Dropbox, Google One, Adobe Creative Cloud, Slack, ChatGPT Plus, Zoom, GitHub Copilot, PlayStation Plus, Xbox Game Pass, Nintendo Switch Online, Discord Nitro and Tinder Gold.
• Name autocomplete suggests templates while the user types.
• Cancel Subscription button on the detail screen opens the provider’s cancel page.
• Custom services with any name, price and colour, for gym memberships, SaaS tools or anything else.

4. PIN App Lock, Backup and Restore, and Privacy

SubZero needs no account. Data stays on the phone, and users can protect it with a PIN and save it to a file.

• Optional 4-digit PIN lock on app launch. The PIN is stored as a salted SHA-256 hash, and changing it asks for the old PIN first.
• Backup and restore all subscriptions and settings as a local JSON file. The file is validated before any existing data is replaced.
• Privacy and ads screen with a sample in-app privacy statement you replace with your own.
• 5 display currencies: USD, EUR, GBP, JPY and LKR (display only, no exchange-rate conversion).
• Clear All Data option in Settings.

5. Cyber Dark and Clean Light Themes

A glassmorphism interface with frosted panels in both themes. Dark mode is the default, and users switch themes in Settings.

• Cyber Dark: deep navy with a mint accent.
• Clean Light: soft grey with a deep teal accent.
• Three-slide onboarding with a Skip button, plus a side drawer for Dashboard, Analytics and Settings.

What’s New in Version 1.5.0

• AppConfig: lib/core/config/app_config.dart holds the app name, tagline, company, support email, version, file prefix and brand colours. The About screen, privacy text, PDF report, backup file names and theme all read from it.
• One version source: a single AppConfig.version replaces two conflicting version strings.
• New documentation: rebuilt as a Quick Setup Guide and a Complete Setup Guide.

Included from version 1.4.0:

• Google UMP consent flow: ads are initialised only after consent allows it, with an “Ad privacy options” entry in Settings where required.
• Reliable reminders: reminders now continue after the first billing cycle, and deleted subscriptions no longer keep their reminders.
• Backup restore fix: restored subscriptions can be edited and deleted normally.
• Release-ready setup: unique app ID com.stacklynlabs.subzero, targetSdk 36, release signing through key.properties, and unit tests for billing dates, reminders and restore.

Technical Specifications for Flutter Developers

• Flutter 3.44+ and Dart 3.12: one codebase for Android (targetSdk 36) and iOS (13.0+). Java 17 for Android builds.
• Riverpod 3 state management with riverpod_generator, with providers for subscriptions, settings and sort order.
• Hive local database that recovers from corrupted boxes on start.
• Local notifications: flutter_local_notifications 22 with timezone and flutter_timezone, and the Android 13+ notification permission request.
• PDF reports with the pdf and printing packages.
• File backup with file_picker, and PIN hashing with crypto.
• Clean structure: feature folders for screens, plus core folders for services, constants, config and shared UI.
• Web build for demos: the same code runs in a browser for the live preview. Notifications, backup and restore, PDF export and ads are mobile-only.

Monetization Ready with Google AdMob

• Interstitial ads shown when opening a subscription or adding a new one, capped at 2 per session, with the next ad preloaded.
• Google UMP consent runs before ads are initialised.
• Google test ad IDs are used in debug builds. Add your own AdMob App ID and ad unit IDs before release; the guides explain each step.

Buyer responsibility: you are responsible for all costs, fees and taxes related to third-party ad services such as Google AdMob, for your own privacy policy, and for legal compliance in your target regions.

Easy to Customize and Rebrand the Flutter App Template

• One config file: change the app name, tagline, company, support email and brand colours in app_config.dart.
• Central text: app strings live in one constants file.
• Edit the templates: add, remove or reprice quick-add services in one Dart file.
• Icon and splash: regenerate them with flutter_launcher_icons and flutter_native_splash.

Who Is This Flutter App Template For?

• Founders launching a subscription manager or bill tracker app.
• Fintech and budgeting startups that want an offline personal finance app without backend costs.
• Agencies and freelancers who need a white-label expense tracker for clients.
• Flutter developers who want to learn a real-world Riverpod and Hive app with local notifications.

What Is Included in Your Purchase?

• Complete Flutter source code for Android and iOS, with unit tests.
• Developer documentation: Quick Setup and Complete Setup HTML guides covering setup, rebranding, AdMob and consent, release signing, troubleshooting and FAQ.
• App icon, splash screen and logo assets.
• Free lifetime updates.

Why Build With Stacklyn Labs?

We build professional Flutter apps with a strong focus on clean design and a smooth user experience. SubZero is more than a UI kit. It is a complete, monetizable subscription tracker that you can rebrand and publish on Google Play and the Apple App Store.

Need help? Email support@stacklynlabs.com and our team will get you set up.

AI Disclosure

AI-assisted tools were used to help produce parts of this item, including source code, documentation text and some graphic assets. All output was reviewed, tested and edited by the author, who is responsible for the final item.

Developed by Stacklyn Labs.