Full-Stack Web & Mobile Development

Custom Software Development

From concept to production. React/Next.js frontends, Node.js/Python backends, Flutter & React Native mobile apps, and cloud-native architectures — delivered on time with full source code ownership.

12+ years. 200+ projects. TypeScript by default. 70–80% test coverage standard. Zero vendor lock-in.

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200+Projects Delivered

12+Years Experience

50+Engineers

30+Countries Served

Custom Software vs Off-the-Shelf

Your competitive moat cannot be built on software your competitors also use

CapabilityOff-the-Shelf SaaSCelloIP Custom Build

Code Ownership✗ Vendor-locked, black-box software✓ Full source code & GitHub repo on delivery

Customisation✗ Config-only, rigid feature sets✓ Unlimited — built exactly to your requirements

Tech Stack✗ Vendor decides, often legacy✓ Best-fit modern stack, TypeScript by default

Integrations✗ Limited to supported connectors✓ Any API, protocol, or system via custom code

Scalability✗ Tier-based pricing, unpredictable cost✓ Cloud-native infra, linear cost scaling

Support Model✗ Ticket queue, unknown SLA✓ Dedicated engineer, defined response SLA

Data Residency✗ Vendor cloud — limited control✓ Your cloud, your region, your rules

Competitive Moat✗ Same tool as all competitors✓ Proprietary IP no competitor can replicate

Development Services

End-to-end capability across web, mobile, cloud, and real-time

Full-Stack Web Applications

React/Next.js frontends with Node.js or Python backends, REST APIs, PostgreSQL databases, and production-ready CI/CD deployments on AWS or GCP.

React 18Next.js 15Node.jsTypeScript

Mobile App Development

Flutter and React Native cross-platform apps plus native iOS (Swift) and Android (Kotlin). App Store & Play Store ready with OTA update pipelines.

FlutterReact NativeSwiftKotlin

SaaS Platform Architecture

Multi-tenant architecture, subscription billing (Stripe), RBAC, SSO, usage metering, and the full infrastructure to launch a recurring-revenue SaaS.

Multi-tenantStripe BillingRBACSSO

REST & GraphQL API Development

OpenAPI spec-first API design, versioning strategy, rate limiting, API key management, caching layers, and Swagger docs shipped with every project.

RESTGraphQLOpenAPIRate Limiting

Legacy System Modernisation

Migrate PHP monoliths, Ruby on Rails, or .NET systems to modern TypeScript microservices. Parallel running strategy, zero data loss, instant rollback.

MigrationMicroservicesZero Downtime

Real-Time Applications

WebSocket and Socket.io-powered live dashboards, collaborative editors, real-time notifications, and multiplayer features with sub-100ms sync.

WebSocketSocket.ioLive Sync

Database Design & Optimisation

PostgreSQL, MongoDB, Redis architecture; index strategy, query optimisation, sharding, replication, pgBouncer connection pooling, and backup pipelines.

PostgreSQLMongoDBRedisSharding

Cloud-Native & DevOps

Docker, Kubernetes, Terraform infrastructure-as-code, GitHub Actions CI/CD, monitoring with Grafana/Prometheus, and zero-downtime rolling deployments.

KubernetesTerraformCI/CDAWS/GCP

Modern Tech Stack

We choose the right tool for each project — not the trendiest, not the most convenient

Frontend

React 18

Next.js 15

TypeScript

Tailwind CSS

Vite

Zustand

Backend

Node.js / Express

NestJS

Python / FastAPI

Django

tRPC

Mobile

Flutter / Dart

React Native

Swift (iOS)

Kotlin (Android)

Expo

Firebase

Data

PostgreSQL

MongoDB

Redis

Elasticsearch

ClickHouse

Prisma ORM

DevOps

Docker

Kubernetes

Terraform

AWS / GCP / Azure

GitHub Actions

ArgoCD

Testing

Jest

Vitest

Cypress

Playwright

k6 Load Testing

SonarQube

Full Capability Set

Every capability included as standard — not itemised add-ons

React 18 / Next.js 15 App Router

TypeScript — full stack by default

Node.js, NestJS, FastAPI backends

Flutter & React Native mobile apps

REST & GraphQL API (OpenAPI spec)

PostgreSQL, MongoDB, Redis, Elasticsearch

Multi-tenant SaaS architecture

Stripe / PayPal billing integration

OAuth2 / SSO / JWT authentication

Role-based access control (RBAC)

Real-time via WebSocket / Socket.io

Docker & Kubernetes deployment

Terraform infrastructure-as-code

GitHub Actions CI/CD pipelines

AWS / GCP / Azure cloud-native

Prometheus + Grafana monitoring

Jest / Vitest / Playwright testing

70–80% minimum code coverage

OpenAPI / Swagger documentation

Architecture Decision Records (ADRs)

Legacy PHP / Rails / .NET migration

Third-party API integration (Stripe, Twilio)

WCAG 2.1 accessibility compliance

Full source code & IP ownership

Our Development Process

Agile methodology — weekly demos, continuous feedback, no big-reveal surprises

Discovery & Requirements

Stakeholder interviews, user research, competitive analysis, and technical feasibility. Output: detailed scope doc, success metrics, and sprint plan.

Technical Architecture

System design document, API contracts, database schema, infrastructure plan, and security audit. Reviewed and signed off before a line of code is written.

UI/UX Design

Figma prototypes, design system definition, user testing, and WCAG 2.1 accessibility review. Clickable prototype approved before development sprint.

Agile Development Sprints

2-week sprints, daily standups, PR code review gates, and weekly client demos. Incremental feature delivery — you see working software every 2 weeks.

QA & Testing

Unit, integration, and E2E test suites, performance benchmarking, security scanning, and UAT sign-off against the original acceptance criteria.

Deployment & Handover

Zero-downtime deployment, monitoring setup, runbook documentation, team training, and full source code handover with GitHub repo access.

Project Tiers & Investment

Transparent pricing ranges — no vague "contact for pricing" until you know the ballpark

Starter Project

MVP / Small App

$10K – $30K

5–15 features / screens
React / Next.js web app
REST API + PostgreSQL
Basic auth & user management
4–8 week timeline
Source code + deployment docs

Start Small

Growth Platform

SaaS / Mid-Complexity

$50K – $150K

30–60 features / modules
Full-stack web + mobile app
Multi-tenant SaaS architecture
Stripe billing + RBAC + SSO
Real-time features (WebSocket)
CI/CD + Kubernetes deployment
Grafana monitoring dashboard
3–6 month timeline

Enterprise System

Large-Scale / Custom

$150K+

Complex integrations & APIs
Microservices architecture
Multi-region cloud deployment
Advanced security & compliance
Legacy system migration
Dedicated team (5–10 engineers)
SLA-backed ongoing support
6–12+ month timeline

Contact Sales

Why CelloIP for Custom Software

Specialists with a production track record — not a generalist agency

12+ Years, 200+ Projects

Proven delivery track record across VoIP, fintech, healthcare, edtech, and SaaS. Not a generalist agency — a specialist team.

Full IP & Code Ownership

You receive the GitHub repo, all source code, and full IP rights on delivery. Zero lock-in, hire anyone to extend it.

TypeScript & Testing by Default

Static typing and 70–80% test coverage are non-negotiable defaults — not premium add-ons. Quality is engineered in.

Cloud-Agnostic Architecture

Containerised, cloud-agnostic deployments. Run on AWS, GCP, Azure, or on-prem. No proprietary vendor dependencies.

Telecom & API Specialists

Deep VoIP, WebRTC, and real-time protocol expertise means we build communication features other agencies struggle with.

Post-Launch Support Retainers

Optional 10–20%/month retainers covering bug fixes, security patches, dependency updates, and minor feature work.

200+Projects Delivered

12+Years Experience

50+Engineers

30+Countries Served

Frequently Asked Questions

What is custom software development vs off-the-shelf solutions?

Custom software is built specifically for your business requirements, workflows, and competitive differentiators. Off-the-shelf software (Salesforce, SAP, etc.) serves general use cases with rigid feature sets limited to configuration. Custom development gives you unlimited functionality tailored to your exact needs, proprietary algorithms, unique integrations, and full code ownership. It makes sense when your competitive advantage depends on unique technology, when generic platforms lack critical features, or when you need deep integrations that off-the-shelf tools cannot provide.

How much does custom software development cost?

Pricing depends on scope, team size, and timeline. A simple MVP might run $10K–$30K over 4–8 weeks. Mid-complexity SaaS platforms typically range $50K–$150K over 3–6 months. Large-scale systems with real-time features, complex integrations, and rigorous testing often exceed $150K and take 6–12 months. We use fixed-fee milestones or time-and-materials retainers depending on how well requirements are defined. Hourly rates range $30–$80 depending on seniority. We provide detailed estimates with confidence ranges — no surprises.

How long does a typical project take?

Small projects (5–15 features) take 4–8 weeks. Mid-sized applications (30–60 features, multiple integrations) require 3–6 months. Complex distributed systems can take 6–12 months or more. We break every project into 2-week sprints with weekly demos — you see working software every fortnight, not a big reveal at the end. This also means requirements can evolve without massive rework, as we adapt sprint by sprint.

Do we get the source code and can we maintain it ourselves?

Absolutely — full source code and GitHub repository ownership on delivery. We document the codebase thoroughly: API specs (OpenAPI/Swagger), Architecture Decision Records, deployment runbooks, and inline code comments. All code uses industry-standard frameworks with popular open-source dependencies. You can hire any developer to extend or maintain it after handover. No proprietary frameworks, no black boxes, no ongoing dependency on CelloIP to operate your own software.

Do you work with existing codebases or only greenfield projects?

Both. We regularly take on legacy modernisation projects — PHP monoliths, Ruby on Rails, .NET systems — and migrate them to modern TypeScript stacks. Our approach uses parallel running (old and new system live simultaneously), incremental traffic shifting (10% → 50% → 100%), and instant rollback capability. We have migrated systems with zero data loss and zero unplanned downtime. We also extend existing codebases for feature work or performance optimisation.

What post-launch support do you offer?

We offer optional maintenance retainers at typically 10–20% of the original development cost per month. These cover bug fixes, security patches, dependency version upgrades, performance monitoring, infrastructure scaling, and minor feature enhancements (under 8 hours). Many clients find this more cost-effective than hiring an in-house engineer for maintenance-level work. Retainers include defined response SLAs — critical bugs within 4 hours, standard within 24 hours.

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Let's Build Something Great Together

Whether you have a full spec ready or just a product idea — we will help you scope, architect, and build software that performs in production, scales with your business, and stays maintainable for years.