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Everything a product needs, and nothing it does not.

Six capabilities that combine into a complete product team. Pick one, or hand us the whole thing — the price and the process are the same either way.

01

Mobile Development

React Native · iOS · Android

Native-feeling apps that ship to both stores from one codebase — or fully native when the product demands it.

Typical timeline
2–6 weeks
React NativeExpoSwiftSwiftUIKotlinJetpack ComposeRevenueCatFirebase
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React Native & Expo

One codebase, two stores. EAS build pipelines, over-the-air updates, native modules when we need to drop below the bridge.

Native iOS

Swift and SwiftUI apps with widgets, App Clips, StoreKit 2 subscriptions, HealthKit and background processing done properly.

Native Android

Kotlin with Jetpack Compose, Material 3, WorkManager and Play Billing — tuned for the long tail of Android devices.

Release engineering

Signing, provisioning, phased rollouts, crash monitoring and review-team negotiation. We handle the unglamorous part.

What you get

  • Production apps on the App Store and Google Play
  • Design-system-driven component library
  • Automated build & release pipeline
  • Analytics, crash reporting and A/B testing wiring
02

Web Development

Next.js · React · TypeScript

Fast, accessible, search-friendly web apps built on the modern React stack — no page-speed regrets.

Typical timeline
1–4 weeks
Next.jsReactTypeScriptTailwind CSSFramer MotionVercelPlaywright
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Next.js applications

App Router, server components, server actions, route handlers and edge rendering — architected so the fast path stays fast.

Design systems

Typed, composable component libraries in Tailwind with motion primitives, dark mode and documented usage rules.

Performance engineering

Bundle budgets, image and font strategy, streaming boundaries and caching layers to hold a 95+ Lighthouse score.

Accessibility & SEO

Semantic markup, keyboard-complete flows, structured data, sitemaps and Open Graph handled from day one.

What you get

  • Production web app with CI/CD previews
  • Reusable component + motion library
  • Lighthouse and Core Web Vitals report
  • Editor-friendly content model where needed
03

Backend Development

Node.js · NestJS · PostgreSQL · MongoDB

APIs and data models that stay predictable under load, and that the next engineer can actually read.

Typical timeline
1–5 weeks
Node.jsNestJSTypeScriptPostgreSQLMongoDBPrismaRedisGraphQL
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API design

Versioned REST or GraphQL surfaces with typed contracts, OpenAPI docs, idempotency and sane pagination.

Data modelling

PostgreSQL and MongoDB schemas with migrations, indexing strategy and query plans reviewed before they hurt.

Async workloads

Queues, cron jobs, retries with backoff, webhook ingestion and event pipelines that survive third-party outages.

Third-party integrations

Stripe, RevenueCat, Twilio, Google, Apple, CRMs and ERPs — wired with real error handling, not happy-path demos.

What you get

  • Documented, versioned API
  • Migration-managed database schema
  • Integration test suite
  • Runbooks, logs, metrics and alerts
04

SaaS Development

MVP · Subscriptions · Dashboards · Analytics

End-to-end SaaS products: multi-tenant foundations, billing that reconciles, and dashboards founders actually use.

Typical timeline
3–7 weeks
Next.jsNestJSPostgreSQLStripeRevenueCatRedisPostHog
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MVP development

Scope cut to the smallest thing that proves the business, built on foundations that survive the next three pivots.

Subscription systems

Stripe or RevenueCat billing with plans, trials, proration, dunning, entitlement checks and webhook reconciliation.

Admin dashboards

Role-based internal tooling: user management, impersonation, audit logs, feature flags and support workflows.

Analytics & reporting

Event tracking, funnels, cohort retention and exportable reports — instrumented so growth decisions have evidence.

What you get

  • Multi-tenant application with auth and roles
  • Working billing with test + live reconciliation
  • Admin console and internal tooling
  • Analytics dashboard and event taxonomy
05

Cloud & DevOps

AWS · Firebase · CI/CD · Monitoring

Infrastructure that deploys itself, scales when it should, and tells you before customers do.

Typical timeline
1–3 weeks
AWSFirebaseDockerTerraformGitHub ActionsVercelSentryGrafana
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Cloud architecture

AWS (ECS, Lambda, RDS, S3, CloudFront) or Firebase/GCP, sized to your actual traffic instead of a hypothetical unicorn.

CI/CD pipelines

GitHub Actions pipelines with typecheck, tests, preview environments and one-command rollbacks.

Monitoring & observability

Structured logs, traces, uptime checks, error budgets and alerts routed to the humans who can fix them.

Security & compliance

Secret management, least-privilege IAM, dependency scanning, backups and restore drills that are actually tested.

What you get

  • Infrastructure as code repository
  • Automated deploy pipeline with rollbacks
  • Monitoring dashboards and alert rules
  • Disaster recovery + backup plan
06

Custom Software & Integrations

Internal tools · Automation · APIs

The systems that don't fit a SaaS subscription: internal platforms, automations and integration layers.

Typical timeline
1–4 weeks
TypeScriptNode.jsPythonPostgreSQLClaude APITemporalREST / gRPC
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Internal platforms

Operations tooling, back-office systems and portals that replace the spreadsheet holding your company together.

Integration layers

Middleware between ERPs, CRMs, payment providers and warehouses — with retries, reconciliation and audit trails.

AI features

LLM-powered search, summarisation, classification and assistants built with evaluation harnesses, not vibes.

Rescue projects

Audits and takeovers of half-finished codebases, with an honest report on what to keep and what to rewrite.

What you get

  • Technical audit and architecture plan
  • Integration or platform implementation
  • Data migration scripts with dry-run mode
  • Handover documentation and training
How we work

Six steps from first message to production

The same process every time, whether it is a two-week integration or a six-month platform build.

  1. 01Same day

    Discovery brief

    You send the problem, the constraints and the deadline that actually matters. Both founders read it — including the engineer who would build it — and reply by email the same working day. No account manager relay, nothing to schedule.

    • Problem definition
    • Rough feasibility
    • Budget range
  2. 023–7 days

    Scope & architecture

    We turn the idea into a written scope: user flows, data model, integrations, risks and the parts we recommend cutting from v1.

    • Written scope
    • Architecture sketch
    • Fixed estimate
  3. 033–10 days

    Design & prototype

    Interface design and a clickable prototype so decisions get made against something real instead of a description in a document.

    • UI design
    • Clickable prototype
    • Design system
  4. 041–5 weeks

    Build in weekly slices

    Two-week cycles with a working build at the end of every week. You get a demo link, a changelog and direct access to us in a shared channel.

    • Weekly builds
    • Demo environment
    • Shared Slack channel
  5. 051–2 weeks

    Test & harden

    Automated tests, device matrix runs, load checks, accessibility pass and a security review before anything reaches real users.

    • Test suite
    • QA report
    • Performance budget
  6. 06Ongoing

    Launch & support

    Store submission, deploy pipeline, monitoring and alerting. Then a support agreement sized to what you actually need — often a few hours a month.

    • Production release
    • Monitoring & alerts
    • Handover docs
Also included

The parts most agencies bill separately

These are not upsells. They are how we make sure the thing we hand over keeps working.

Performance budgets

Lighthouse, cold start and p95 latency targets agreed up front and verified before launch.

Security review

Dependency scanning, secret management, least-privilege access and a pre-launch pass.

Handover docs

Architecture notes, runbooks and onboarding written for whoever inherits the codebase.

Post-launch support

Monitoring, alerting and a warranty period. A retainer after that is optional, never required.

Replies under 12 hours

Not sure which of these you need?

Run the calculator for a realistic range, or write to us and we will scope it with you by email.

Get a project estimate
Email us

Or email us directly at info@kellosolutions.com