Custom software development services
We design and develop business software and applications perfectly aligned with your processes, operational challenges and information system. From design to production and run, we cover the full lifecycle and augment your applications with AI when it adds value.
/ Our clients
Our expertise
We develop all types of applications. Each solution is designed to integrate with your IS and sustainably support your business.
AI-native applications
Applications where AI is at the core of how the software works: models, agents and automation built in, not bolted on. Designed, secured and operated in production.
Works council (CSE) solutions
We leverage our proprietary Logi-CE solution and custom developments to meet the organizational and regulatory requirements specific to each entity.
HR management tools
Development of employee management tools for careers, appraisals, staffing or performance tracking, integrated into your existing environment.
Custom ERP
Design of business management solutions adapted to your specificities to structure and streamline activity: project oversight, resource management and financial tracking.
Dedicated sector-specific solutions
Creation of applications dedicated to your sector or internal processes, designed around your business rules and operational constraints.
Digital products for your clients
Development of digital platforms intended to be sold to your clients, designed to be robust, scalable and maintainable.
/ Agile and collaborative methodology
We manage your application projects using agile methodology to secure decisions, control costs and deliver a solution suited to actual usage.
Project scoping
Analysis of business needs, existing processes and technical constraints to define functional scope and project priorities.
UX/UI design
Design of user journeys, screens and functional specifications to validate ergonomics and alignment with real usage.
Iterative development
Application development in successive iterations, with regular deliveries to adjust features and validate decisions.
Testing and validation
Functional and technical testing to ensure quality, performance and reliability before going live.
Launch & support
Live deployment of the solution, user training and post-deployment support to ensure rapid and lasting adoption.
/ Technologies
We select the most appropriate technologies for your context, security constraints and expected scalability. Our approach favors robust, maintainable solutions aligned with your information system.
A technical stack tailored to your business challenges and existing IS.
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Castelis commitments
We design reliable, scalable and genuinely useful business applications for your teams. Our approach combines a deep understanding of your challenges, technical expertise and long-term support.
From design to operation, we guarantee consistency, cost and timeline control, with one clear objective: making your application a concrete performance driver.
/ They transformed their operations with custom applications
Discover how our clients gained fluidity and efficiency through business applications developed specifically for their needs.
Dream Yacht Charter | Automating cross-billing
Automation and securing of intercompany flows to consolidate group accounting at D+1.
Lucernys | Improving the profitability of a consulting firm
Deployment of the Chronos Business Management ERP to centralize project tracking and manage profitability.
Prodistribution | Consolidating group accounting data
Centralized accounting interface system to automate financial flows for 150 companies under the Picard, Casino and Franprix brands.
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FAQs — application development
A custom business application adapts precisely to your processes, organization and specific constraints. Unlike standard software, it avoids functional compromises, limits workarounds by teams and integrates more naturally with your existing information system.
Private companies, industries, institutions and local authorities can all benefit from a custom business application. This approach is particularly relevant when needs are specific, complex or insufficiently covered by market solutions.
We integrate UX and UI from the earliest project phases, with design workshops involving users. After go-live, we also support teams with training sessions to facilitate adoption.
Yes, we favor an agile methodology to allow regular adjustments, better cost control and continuous validation of functional and technical decisions throughout the project.
We support our clients after go-live with maintenance, support and evolution services to ensure the long-term sustainability and adaptability of the solution.
Each project is bespoke, so the budget depends on the functional scope, integrations with your IS and the level of requirements (security, performance, run). Rather than a standard price, we provide an estimate after an initial scoping phase, aligned with the value at stake.
The code we develop specifically for you belongs to you. We deliver the sources and documentation, with no imposed dependency, so you remain in control of your tool.
Let's talk about your project
