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Service
Mobile app backend, API and Firebase development
We build the backend a mobile app needs and nothing more: Firebase services for auth, data, files, push and serverless logic, or integration with the API you already run. We also build the admin panels and remote configuration that let you operate the app after launch. Our own apps and internal tools run on this stack.
- Firebase
- Authentication, Cloud Firestore, Cloud Functions, Storage, Cloud Messaging, Crashlytics, Hosting
- Functions
- Node.js and Python Cloud Functions (both in production for our tools)
- APIs
- REST and GraphQL integration; server-side validation
- Operations
- Admin panel (Flutter web), remote config, scheduled jobs, security rules with tests
Does your app need a backend?
Not always. Several of our own apps process photos and video entirely on the device and need no server for their core job. A backend becomes necessary when the app has accounts, shared or synced data, subscriptions, server-driven content or notifications. We decide this in discovery, because it is the biggest driver of cost after screen count.
Firebase for mobile apps
| Service | Used for |
|---|---|
| Authentication | Email, Google and Apple sign-in, anonymous accounts that upgrade later |
| Cloud Firestore | App data, user documents, remote configuration and feature flags |
| Cloud Functions | Business logic, receipt validation, scheduled jobs, webhooks, server-rendered pages |
| Storage | User uploads with per-user access rules |
| Cloud Messaging | Push notifications with device registration and topic targeting |
| Crashlytics | Crash reporting from production devices |
| Security rules | Per-collection access control, written and tested with the Firebase emulator |
Working with your existing API
If your product already has a backend, the app should use it. We build a repository layer in the Flutter app over your REST or GraphQL API with authentication, pagination, retries, caching and versioning handled in one place, and we tell you early if the API needs endpoints the mobile app cannot work without.
Admin panels and operational tooling
An app you cannot operate is a liability. For our own portfolio we built a Flutter web admin panel backed by Cloud Functions that manages app records, privacy policies, ad settings, push notification templates and release plans, and checks each app's store listing nightly. We build the same kind of tooling for client apps: the screens your team needs to run the product without a developer.
Security basics we do not skip
- Security rules for every collection and bucket, covered by automated tests
- Server-side validation for anything with money or permissions attached
- Secrets kept out of the app binary; tokens stored in secure storage
- Rate limiting and spam controls on public endpoints
- Least-privilege service accounts for Cloud Functions
Evidence: mobile app backend and api development in our own apps
These are CarrySo's own products, published on Google Play under our developer account. Figures are taken from Google Play when this site was built; each card links to the case study.
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Frequently asked questions
Do you only work with Firebase?
Firebase is our default for new apps because it covers auth, data, files and push with little infrastructure to run. We also integrate with existing REST and GraphQL APIs and can build Cloud Functions in Node.js or Python around them.
Can you build an admin panel for our app?
Yes. We build web admin panels in Flutter for managing users, content, plans and configuration, the same approach we use for our own apps.
How do you handle remote configuration?
Our apps read configuration from Cloud Firestore at startup through a shared package we maintain. It controls update prompts, feature flags and ad frequency without a store release. We can add the same to your app.
Guides on this topic
How to Build a SaaS Mobile App: A Practical Guide
A step-by-step guide to building a SaaS mobile app: architecture, auth, onboarding, subscriptions, backend, push notifications, admin panel, store rules and launch.
Flutter SaaS App Architecture: Layers, State and Data
A reference architecture for Flutter SaaS apps: feature-first folders, a repository layer, state management, auth and entitlements, offline caching and testing.
Mobile App Subscription Architecture Explained
How to architect in-app subscriptions for Android and iOS: store billing, server-side receipt validation, entitlements, restore purchases, trials and edge cases.
Related services
Mobile app development
Mobile app development from idea to app store: Flutter apps for Android and iOS, SaaS mobile apps, MVPs, UI/UX, backend APIs, store deployment and maintenance.
SaaS mobile app development
Mobile apps for SaaS businesses and mobile-first SaaS products in Flutter: subscriptions, auth, onboarding, dashboards, payments, push, APIs and admin panels.
Flutter app development
Flutter app development for Android and cross-platform apps: architecture, state management, Firebase, on-device processing, testing and store release.
Mobile app maintenance and updates
Mobile app maintenance for Flutter apps: crash monitoring, SDK and target API updates, Google Play policy compliance, update prompts and regular releases.
Have an app idea or an app that needs help?
Tell us what you want to build. We'll reply by email with questions, and then with a proposed scope and estimate.