The backend behind your product
APIs, databases, and infrastructure for products that don’t need a web frontend — the backend behind a mobile app, an integration layer between systems, or a data pipeline, engineered to scale and documented enough to hand over.
Why work with us on the backend
A backend built in isolation from the app or system it serves tends to drift from what that app actually needs. We build backends the same way we build the products on top of them — one team, one contract, no handoff.
One team across the whole stack
When we also build the iOS, Android, or web client, the same engineers write the backend — the API contract does not drift between two teams that never talk. Kiolfast’s cost calculations have to agree on every device at once because one team built all of it.
Infrastructure we run ourselves
Node.js, PostgreSQL, and Docker — the same self-hosted stack applefy.tech itself runs on — not a managed platform that bills you monthly for the privilege of deploying your own code.
An API contract defined before the first endpoint
Data models, auth, and versioning are agreed up front with whoever consumes the API — your own app team, ours, or a third party — so the contract does not change shape mid-build.
You own the infrastructure
Containerized deployments, handed over documented and runnable by your own team. No vendor lock-in, and no dependency on us staying available to keep it running.
What we deliver
API Design & Architecture
REST APIs, authentication, authorization, and versioning, scoped to what the consuming app or system actually needs — not a generic CRUD layer bolted on afterward.
Database & Data Modeling
PostgreSQL schema design and migrations — data models built for the queries your product actually runs, with a migration path that doesn’t require downtime.
Third-Party & System Integration
A backend layer that connects your product to payment processors, KYC/AML providers, CRMs, or systems you already run — built to the APIs they expose, not around them.
Deployment & Infrastructure
Containerized deployment — self-hosted or on infrastructure you choose — with CI/CD, monitoring, and a setup your own team can operate after we hand it over.
Common questions about backend development
Web Development is our full-stack service for products that need a web application or website — frontend and backend together, built on React, Next.js, Node.js, and PostgreSQL. Backend Development is scoped to the other case: the API and data layer for a product that does not need a web frontend at all — the backend behind a mobile app, an integration layer between systems you already run, or a data pipeline. If you need both a web app and its backend, start with Web Development; if you need an API without a web UI attached to it, this is the right page.
Node.js for the API layer, PostgreSQL for the database, and Docker for containerized, self-hosted deployment — the same self-hosted stack applefy.tech itself runs on. We’ll work with infrastructure you already have where that’s the better call.
Yes. We define the API contract with your team up front, build to it, and document it so your frontend team can work against it independently. We also take over backends an earlier team left behind, after reading the existing code before proposing to change any of it.
Yes. We scope to the API your app already expects, or redesign it with you if the existing one doesn’t hold up under real usage. Kiolfast is the reverse case — we built the iOS app, the Android app, and the backend all underneath one team — but a backend-only engagement works the same way.
The same three tiers as any Applefy project: $20K-$40K for a simple API over 3-6 weeks, $40K-$100K for a mid-complexity backend with several integrations over 2-4 months, and $100K-$250K+ for a complex, multi-system backend over 4-8 months. Third-party integrations and data-migration requirements are usually what move a project from one tier to the next.
You do. The repository, the database, and the deployment configuration are handed over documented and runnable by your own team — the same policy as every Applefy build.
Explore other services
Book a call with our CEO
Denys Havryliak
Founder & CEO
- 10+ years in Software Engineering
- Master’s in Cybersecurity
- Deep, current knowledge of AI tooling
You’ll talk to the person who builds. Denys works hands-on across product, architecture, and delivery — and keeps a close watch on what today’s AI tooling can genuinely do in production, not just in a demo.