Backend and APIs
Mobile App Backend Development and APIs Built to Last
Our mobile app backend development service builds the part of your app users never see: APIs, authentication, databases, file storage, push notifications, payments, background jobs and the admin tools your team runs the business from. We choose between backend-as-a-service and a custom backend on evidence, design for the scale you expect, and hand you a system your next team can understand.
- BaaS or custom, chosen on evidence
- Versioned, documented APIs
- Monitoring and alerts from launch
- Runs in your cloud account
What a mobile app backend includes
Most apps need the same building blocks: user accounts and sign-in, a database, file and image storage, an API the app calls, push notifications, scheduled and background jobs, payments and webhooks, email or SMS, and an admin panel. The differences lie in how much custom business logic sits on top, how real-time the data must be, and what compliance rules apply.
The backend is also where an app’s long-term cost and risk live. A screen can be redesigned in a sprint. A data model that cannot represent your second business line, or an API with no versioning, can lock you into a painful rewrite. That is why we treat backend design as a first-class part of discovery, not something bolted on after the UI.
We build backends for new apps alongside our iOS, Android and cross-platform projects, and as standalone work for teams that already have an app.
BaaS vs custom backend: how to choose
Backend-as-a-service platforms give you auth, database, storage and functions out of the box. A custom backend gives you full control. Neither is better in general; each fits a different stage and product.
| Factor | BaaS (Firebase, Supabase) | Custom (Node.js, Laravel and similar) |
|---|---|---|
| Time to first release | Fastest: auth, database and storage ready | Slower start; more set-up and plumbing |
| Business logic | Fine for simple rules; complex logic spreads across functions | Clear home for complex workflows and integrations |
| Data model | Firestore is NoSQL; Supabase is full Postgres | Any database; usually Postgres or MySQL |
| Real-time and offline | Strong built-in support | Built with WebSockets or a sync layer |
| Cost at scale | Pay per read, write and function call; can surprise | Pay for servers; more predictable, more ops work |
| Lock-in | Higher with Firebase; lower with Supabase (self-hostable) | Lowest; portable between clouds |
| Compliance needs | Check region, BAAs and data controls per provider | Full control over hosting and data flows |
Choose BaaS for an MVP with standard features and a small team. Choose custom when you have heavy integrations, complex permissions, strict compliance or predictable high volume. A hybrid (BaaS auth and push, custom API for business logic) is common.
Backend technologies we work with
We pick the stack per project and explain why. These are the technologies we use most.
Node.js
TypeScript APIs with NestJS or Express, a good fit for real-time features and teams that also write React Native. We run only Active or Maintenance LTS releases in production.
Laravel
A productive PHP framework with queues, auth, admin tooling and a first-party AI SDK in Laravel 13. Strong for business apps with lots of CRUD and reporting.
Firebase
Cloud Firestore with realtime listeners and offline support, Firebase Authentication and Cloud Messaging. Fast for MVPs and chat-style apps. Prefer Postgres? See Supabase app development.
Supabase and Postgres
Every Supabase project is a full Postgres database with auth, storage, realtime and edge functions, and it can be self-hosted later.
Payments
Stripe, PayPal, Apple Pay and Google Pay, plus JazzCash and Easypaisa for Pakistan, with webhooks and reconciliation.
Cloud and DevOps
Cloud backend setup and hosting on AWS, Google Cloud or Azure; containers, managed databases, infrastructure as code and CI/CD with GitHub Actions.
API design for mobile apps
Mobile APIs have constraints web APIs often ignore. Old app versions stay installed for months, networks drop mid-request, and every extra round trip costs battery and patience. We design for that from the first endpoint.
REST or GraphQL. REST with an OpenAPI specification is our default: easy to cache, monitor and hand over. GraphQL earns its place when many screens need differently shaped data from the same objects. Our REST and GraphQL API development page compares the two in depth. Versioning. Breaking changes go into a new version, and a minimum supported app version lets you force upgrades when you must. Resilience. Idempotency keys on payments and orders, so a retried request does not charge twice; pagination on every list; consistent error codes the app can act on.
Every API ships with documentation and generated client code, so a new developer, or a new agency, can work with it on day one. Deep links need backend work too, because the Universal Links and App Links verification files live on your domain; our guide to deep linking in mobile apps covers the setup.
API standards we follow
- OpenAPI spec kept in the repository
- Versioned endpoints and minimum app version
- Token auth with refresh and revocation
- Idempotency keys on payments and orders
- Rate limiting per user and per key
- Consistent error format and codes
- Contract tests in CI
Not sure which backend fits your app?
Send us your feature list, expected users and any compliance needs. Within one business day we will reply with a recommended architecture (BaaS, custom or hybrid), the main risks and the next step toward a fixed quote.
Scaling: design for the next order of magnitude
Over-engineering for millions of users you do not have wastes money. Under-engineering for the launch spike you know is coming loses users. We design for roughly the next order of magnitude of traffic and make sure the path beyond it is clear.
In practice that means stateless API servers behind a load balancer, a managed Postgres or MySQL database with read replicas when needed, a cache such as Redis for hot reads and sessions, a queue for slow work (emails, image processing, report generation, AI calls), and files on object storage behind a CDN. Real-time features use WebSockets or a BaaS realtime layer, depending on the stack. Apps that must keep working without signal also need a sync design; see our guide to offline-first mobile app architecture.
Before launch we load test the endpoints that matter most, such as sign-up, feed and checkout, against expected peak traffic, and fix the slow queries we find. In our experience, missing indexes and N+1 queries cause more production incidents than server size.
Observability and security from day one
A backend you cannot see into is a backend you cannot support. These are in place before the first public release.
- Structured logs with request IDs that link app errors to server logs
- Error tracking with Sentry on the server and Sentry or Crashlytics in the app
- Metrics and dashboards for latency, error rate and throughput
- Alerts routed to the contacts named in your support agreement, by severity
- Uptime checks on public endpoints
- Automated daily database backups with a tested restore
- Secrets in a managed vault, never in code or the app
- Dependency and container scanning in CI
- Audit logs for admin and sensitive actions
- Separate development, staging and production environments
What drives backend running cost
Build cost follows scope and integrations. Running cost depends on the architecture, and it is easy to get wrong. On BaaS platforms you pay per read, write, function call and gigabyte, so an inefficient screen that re-reads a whole collection can cost more than the server it replaced. On a custom backend you pay for servers, databases and bandwidth whether traffic arrives or not.
The levers we use: right-sized managed services, caching and pagination, image resizing at upload rather than on every view, queues to smooth spikes, and storage lifecycle rules for old files. We estimate monthly running cost at your expected users during discovery and set billing alerts in your cloud account. For whole-project budgets see app development cost, and for a deeper comparison of stacks read our guide to the best backend for mobile apps.
How our mobile app backend development projects run
Backend work follows the same delivery model as the rest of our projects. NDA first, code in your repository, infrastructure in your cloud account.
Discovery (one to two weeks)
Data model, integrations, permissions, expected load and compliance needs. Output: architecture diagram, API outline, backlog and fixed price.
Foundations
Environments, CI/CD, auth, database migrations, logging and error tracking set up before feature work starts.
API-first sprints
Two-week sprints. Endpoints are specified in OpenAPI first, so app and backend developers work in parallel against mock servers.
Integration and load testing
Third-party services in sandbox, then load tests on critical paths and a security review against the OWASP API risks.
Launch and handover
Runbooks, architecture notes, dashboards and access handed to you. Ongoing support through our app maintenance and support plans.
Admin panels, AI services and existing backends
Nearly every app needs an internal tool for support, content and operations; we build these through our admin panel and dashboard development service. Apps with LLM features need an AI service layer so keys stay on the server; see generative AI and LLM integration. Corporate apps that must talk to ERP, CRM and identity systems are covered under enterprise mobile app development.
If you already have a backend that is slow, fragile or undocumented, we start with an audit and a plan rather than a rewrite; our app modernization and rescue service covers that. To add backend engineers to your own team, see hire backend developers.
Backend projects and client feedback
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Mobile app backend development FAQs
Should my app use Firebase or a custom backend?
Firebase is a strong choice for MVPs with standard features, realtime data and a small team, because auth, database, storage and push are ready to use. A custom backend makes more sense for complex business rules, heavy integrations, strict compliance or predictable high volume. Many apps combine them. We recommend one in discovery based on your features and growth plans.
Can you build a backend for an app we already have?
Yes. We document what the app expects, design an API that serves it, and migrate data from the current system if there is one. Where the existing app calls a BaaS directly, we can introduce a custom API gradually, one feature at a time, so you avoid a risky big-bang switch.
Which cloud provider do you use?
Whichever suits you: AWS, Google Cloud or Azure, or a BaaS such as Firebase or Supabase. The account is opened in your company’s name, so you hold billing, data and access. We recommend a region close to your users and one that meets your data protection obligations.
How do you handle offline use in the app?
It depends on the data. Firestore offers offline support out of the box. With a custom backend we cache data on the device, queue changes made offline, and sync when the connection returns, with clear rules for conflicts such as last write wins, server wins or asking the user. We decide those rules per feature in discovery.
How will we know if the backend has a problem?
Monitoring is part of the build. Error tracking, metrics dashboards, uptime checks and alerts are live before launch, and logs carry request IDs that tie an app error to the exact server request. Alerts go to the people named in your support agreement, and you get access to every dashboard.
Who owns the backend code and infrastructure?
You do. Code lives in your repository from day one, infrastructure runs in your cloud account, and secrets sit in your vault. We sign an NDA before discovery and hand over runbooks and architecture notes at launch. See NDA and IP protection for details.
Get a backend plan before you build
Book a 30-minute architecture call. Bring your feature list and growth assumptions, and you will leave with a recommended stack, the main scaling and cost risks, and what discovery would cover.