Custom software
development
We build custom web systems, SaaS dashboards, and cross-platform mobile apps. From Next.js portals to React Native interfaces, get premium product engineering built for high user volume.
Popular custom software solutions
Browse our most requested services — or book a call and tell us exactly what you need.
End-to-end web & mobile development
We don't build landing pages or Webflow sites. We build software — applications with logic, data, users and real operational requirements.
Next.js web applications
Full-stack web applications built with Next.js and React — from customer-facing products to internal business tools. Server-side rendering, API routes, authentication, database integration and deployment on Vercel or AWS. Every application is built for performance, maintainability and scale from the first line of code.
- Server-side rendered web apps
- REST and GraphQL APIs
- Authentication systems
- Multi-tenant architecture
React Native mobile apps
Cross-platform mobile applications that run natively on iOS and Android from a single codebase. We build React Native apps for startups, SaaS products, trading tools and internal business use — with full App Store and Google Play submission support included.
- iOS & Android from one codebase
- Expo & bare React Native
- App Store & Play submission
- Native device integrations
SaaS platform development
Multi-tenant SaaS platforms built for scale — subscription billing, user roles and permissions, admin dashboards, usage metering and the infrastructure to support a growing customer base. We build SaaS products from MVP to production-ready, and take over existing codebases that need refactoring or scaling.
- Multi-tenant architecture
- Stripe subscription billing
- Role-based access control
- Admin dashboards
AI-powered applications
Web and mobile applications with AI embedded at the core — not bolted on. OpenAI and Claude integrations, RAG-powered search and Q&A, AI-generated content and summaries, document processing pipelines and intelligent automation built directly into your product's user experience.
- OpenAI & Claude integrations
- RAG-powered search & Q&A
- Document processing pipelines
- Vector database setup
Custom AI model development
Fine-tuned language models, computer vision systems and custom neural networks for products that need AI trained on specific data. We build and train models for document classification, image recognition, anomaly detection, demand forecasting and domain-specific NLP — delivered with full model weight ownership.
- Computer vision models
- Fine-tuned LLMs
- Anomaly detection models
- Training pipeline docs
Trading dashboards & portals
Custom web-based dashboards for traders, signal providers, prop firms and fund managers. Live data feeds, P&L tracking, performance analytics, drawdown alerts, account management and subscriber portals — built to handle the data volume and real-time requirements of live trading operations.
- Live data feed integrations
- P&L & performance analytics
- Drawdown alerts
- Subscriber portals
Internal tools & business apps
Bespoke internal software for operations, logistics, HR, finance and compliance teams. Replace spreadsheets and disconnected SaaS subscriptions with a single application built around your exact workflow — with the integrations, user roles and reporting your team actually needs.
- Workflow-specific logic
- Role-based access control
- Custom integrations
- Reporting & analytics
Technologies we build with
Hover or click on any technology to view our development capabilities, included services and official tools.
Next.js & React
Tap to view details
TypeScript
Tap to view details
PostgreSQL & DB
Tap to view details
AWS & Cloud
Tap to view details
AI & OpenAI
Tap to view details
React Native
Tap to view details
Node.js & APIs
Tap to view details
Custom AI Models
Tap to view details
Web & app projects we've delivered
Real projects. Real outcomes. Built for live users and live business operations.
AI diamond analysis & buying platform
GIA certificates alone can't reveal every flaw — buyers had no way to see light leakage, hidden inclusions, or symmetry issues before committing thousands of dollars to a diamond.
Two veteran diamond suppliers wanted to help engagement ring buyers avoid overpaying — but a GIA certificate alone hides real flaws: light leakage from poor cut proportions, high-risk inclusions certificates minimize, and off-center tables that reduce brilliance even in "Excellent" graded stones. Buyers had no easy way to catch this before spending thousands.
A proprietary AI diamond analysis tool using computer vision to scan actual diamond images and certificate photos — detecting light leakage, dead zones, high-risk inclusions and symmetry issues that grading reports alone don't surface. Paired with an AI-powered diamond search across millions of certified natural and lab-grown stones, plus a platform for unbiased retailer reviews and free expert consultations.
Buyers can now upload a diamond report or image and get an instant visual breakdown of hidden flaws before they spend a dollar, alongside search and comparison tools spanning millions of stones. The platform has helped thousands of couples buy with confidence, backed by a 4.9/5 Google rating.
AI-Powered Group Trip Planning App
Group outings require juggling everyone's preferences, dietary needs, timing and budget by hand — while local venues had no easy way to get discovered or understand who was booking with them.
Planning a group outing — a family day, a date night, or a friends' get-together — normally means juggling everyone's preferences, dietary needs, timing and budget across multiple apps and bookings by hand. On the other side, local restaurants and activity providers had no easy way to get discovered by planners or understand who was booking with them.
A mobile-first AI planning app ("Jaunt") where users add trip members, set meal timing, dietary restrictions, theme (romantic, family, friends) and budget, and receive an AI-generated multi-stop itinerary with bookings handled automatically. Built in React Native with a Django/AWS backend and an OpenAI-powered recommendation engine, paired with a business-side dashboard giving venues visibility into bookings, cancellations and customer demographics.
Consumers get personalized, ready-to-book outings in minutes instead of manually researching and coordinating across multiple apps. Venues gain a new discovery channel plus real operational analytics — turning every planned outing into bookable, trackable business for local partners.
AI document intelligence system for a national regulator
Decades of regulatory documents sat in rigid folder structures with no way to search by meaning, and incoming filings had no consistent way to be classified.
A national securities regulator holds decades of acts, ordinances, rules, regulations, circulars and enforcement orders across dozens of categories. Locating a specific document meant manually browsing rigid folder structures, with no way to search by meaning or content and no consistent way to classify incoming filings.
Government-grade document digitization pipeline combining OCR-based processing to convert scanned and legacy documents into structured, searchable text, an ElasticSearch-powered semantic search engine, and NLP classification to automatically categorize documents by type and regulatory area. Built with a compliance-focused architecture on AWS to meet the security and auditability standards required of a public-sector system.
Staff and the public can now search the regulator's full document archive by meaning and content rather than folder navigation, with new filings automatically classified and indexed as they arrive — replacing manual document handling with fast, auditable retrieval at government scale.
Why clients choose PSI Square for web & app development
Full-stack capability under one roof
Frontend, backend, database, infrastructure, AI integrations, custom model training and mobile — we cover the full stack. No overhead from coordinating multiple specialists. One team, one point of contact, one standard of delivery across every layer of your product.
Built to be maintained, not just launched
We write clean, documented, component-driven code that your team or any future developer can understand and extend. No black boxes, no undocumented workarounds, no clever code that only the original developer can read.
Production from day one
Every application is built for live users and live load — not optimised after launch. Performance, security, error handling and scalability are built into the architecture from the start, not retrofitted when problems appear.
You own everything, always
Full source code ownership on every project — including trained model weights, training pipelines and workflow configurations where applicable. No vendor lock-in, no licensing fees, no proprietary dependencies on our own tools or infrastructure.
How we work
A structured process that keeps your project on track from brief to live deployment.
Free consultation
We start with a 30-minute call to understand what you're building, who it's for and what technical requirements are already defined. We'll ask about your existing stack, your user base and any integrations you need — and give you an honest view of what's achievable and in what timeframe.
Scope & specification
We produce a written scope document covering architecture decisions, tech stack, feature list, integrations and delivery phases. For projects involving custom model training, this includes a data requirements assessment. You sign off on the spec before development begins.
Development in sprints
Development begins within 5 business days of approval. We work in focused sprints with regular deliverables — so you see working software throughout the build, not just at the end. Staging environment access provided from the first sprint.
QA & testing
All applications go through functional testing, cross-browser and cross-device testing, and performance review before delivery. Custom AI models are evaluated against held-out test sets. For mobile apps, we test on real devices across iOS and Android before App Store submission.
Deployment & handoff
Full deployment to your chosen infrastructure, with documentation, a codebase walkthrough and a handoff session. Post-launch support available. Most clients return for their next phase within 90 days.
Is this the right fit for you?
We work best with clients who have a clear product vision and value software that's built to last.
This is a strong fit if you
Have a defined product, tool or application you want built — not just a vague idea
Need a full-stack team that can own the entire build, including AI and model layers
Want production-quality code with documentation you can hand to any developer
Are building a SaaS product, internal tool or customer-facing application with real users
Want a development partner, not just a contractor who disappears after delivery
Probably not the right fit if you
Need a simple marketing website or landing page — we're not the most cost-effective option for that
Don't have a defined feature set and want us to design your product strategy from scratch
Are primarily comparing on hourly rate rather than total outcome and code quality
Need something built and live in under a week with no specification
Not sure what you need? Book a free call — we'll tell you honestly whether we're the right fit and, if not, what kind of team you should be looking for.
What clients say about working with us
Real feedback sourced directly from verified clients, Direct NDA projects, and live deployments.
"The Next.js dashboard they built replaced our entire spreadsheet reporting setup. It's fast, the data is live and the AI-generated summaries save our team hours every week. Exactly what we asked for, on time and documented properly."
Frequently asked questions
Find immediate answers about our tech stack, timelines, code ownership, AI model training, and how we price projects.
How projects are priced
Web and mobile projects vary significantly in scope — an internal admin tool and a multi-tenant SaaS platform with a custom AI model layer are completely different engagements. We scope every project individually and provide a fixed-price quote so you know exactly what you're getting before development begins.
Book a free 30-minute consultation. We'll scope exactly what you need and send you a detailed quote within 24 hours.
Ready to build your product?
Whether you need a Next.js web application, a React Native mobile app, a full SaaS platform or a product powered by a custom-trained AI model — tell us what you're building. We'll scope it, architect it and deliver it to production standard. Most projects start within 5 business days.
Or email info@psi-square.net · We reply within 24 hours · NDA available on request