Best fit
A SaaS platform, customer portal, internal operations tool, or data-rich workflow where domain rules and integrations are central to the product's value.
Custom Web App Development
CoreLine builds custom web applications for product teams that need more than templates. SaaS platforms, internal tools, customer portals, and data-intensive dashboards - designed, built, and shipped by senior engineers who own delivery end-to-end.
SaaS & Platforms
Multi-tenant architecture
Subscription and billing
API-first design
Internal Tools
Admin dashboards
Workflow automation
Reporting and analytics
Customer Portals
Self-service interfaces
Account management
Real-time data views
Engagement fit
Do you need a custom web application?
Last reviewed
Reviewed by
Dominik Dragičević, Founder and CEO
Custom development is justified when a product's workflows, data model, integrations, permissions, or scale create lasting value that an off-the-shelf tool cannot provide. CoreLine designs and builds the application as an owned product asset, including its architecture, delivery pipeline, testing, and production operations.
Not the right fit
A standard marketing site, a short-lived campaign, or a workflow already covered well by a maintained product that can be configured without risky custom code.
First engagement
A scope and architecture phase that defines users, critical workflows, data ownership, integrations, security requirements, and the smallest valuable production release.
Estimation method
We estimate from agreed user flows, system boundaries, dependencies, non-functional requirements, and delivery risks, then separate the first release from optional follow-on scope.
Sound familiar?
You've outgrown your no-code or low-code platform and need a real engineering team
Your web app needs to handle complex business logic that off-the-shelf tools can't support
Previous agencies delivered a demo, not a production system - you need it done right this time
Your team has domain expertise but needs a development partner to build the product
How we build
Every web app engagement starts with scope definition and architecture. We ship working software every two weeks, with CI/CD and production observability from sprint one.
Scope & Architecture
We define the data model, API surface, authentication, and infrastructure before writing application code. You approve the architecture before development begins.
Iterative Development
Two-week sprints with demo and review. Frontend and backend work in parallel against locked API contracts. Every PR passes automated testing and senior code review.
Launch & Scale
Production deployment with monitoring, error budgets, and performance baselines. Post-launch we support scaling, feature development, and infrastructure optimization.
Delivered outcomes
4+ years
continuous web platform partnership
Insync Insurance - quoting, claims, admin, and reporting
Evidence: Insync Insurance case study →Up to 1M/month
website visits informing product research
Nabava.net traffic analytics used during the app redesign
Evidence: Nabava.net case study →3 apps
in one connected industrial platform
Marex client, admin, and super-admin applications
Evidence: Marex case study →
What we work with
Using solutions such as React Native, Flutter, AWS, and many others makes it possible for us to upgrade your product as much as possible and to achieve a thriving collaboration. Here you will find our guide through our most used technologies and case studies related to each one.
AWS
AWS offers the tools to build powerful, flexible, and scalable applications, from compute and storage to databases and content delivery.
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Flutter
Simply put, Flutter is Google’s cross-platform framework that lets you build mobile, web, desktop, and embedded apps, all from a single codebase.
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React Native
React Native is Facebook’s cross-platform framework that combines the best of React with native platform features - perfect for new projects or enhancing existing ones.
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Other technologies we use
PHP
Node.js
Vue.js
React.js
Frequently asked questions
Primary stack: TypeScript, React, Next.js for frontend; Node.js, Python, Go for backend; PostgreSQL and Redis for data; AWS and GCP for infrastructure. We choose the stack that fits the product requirements, not the other way around.
Yes. We regularly join existing projects, audit the codebase, and extend functionality. If the existing architecture is sound we build on it; if it needs improvement we propose specific changes with clear rationale.
We model domain logic explicitly using patterns appropriate to complexity: service layers for straightforward CRUD, domain-driven design for complex multi-entity workflows. Business rules are testable, documented, and separated from infrastructure concerns.
We estimate from validated user flows, the data model, integrations, roles and permissions, security and reliability requirements, migration work, and delivery risks. Discovery separates the smallest valuable production release from optional scope so proposals can be compared on the same boundary.
You do. Code, repositories, infrastructure configuration, and data are yours from day one.
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ready to start?
Tell us what you need built, modernized, or unblocked. We scope it in one call.