Custom web apps, client portals, and SaaS platforms built around your processes — for when off-the-shelf tools no longer cover the job. From a portal with payments and e-signatures to multi-tenant SaaS
Off-the-shelf tools are great — right up until your business stops being “like everyone else’s”
Why would a business need a custom web app?
When I designed my own client portal, I honestly looked for a ready-made product first. No off-the-shelf solution covered even 60% of the requirements — so I built my own: today it has about 91 modules, from billing to document signing. I’m a digital product engineer and web solutions architect with over 18 years of experience — from WordPress core customization to full SaaS platforms and AI agents. A custom web app is your business processes turned into software that works exactly the way you do.
Client portal: account, payments, documents
My Clients portal is an example of what a custom client account looks like in real work:
passwordless login — email plus a 6-digit PIN or Google One Tap: clients never invent or forget passwords
online payments — LiqPay and MonoPay with webhook signature verification and protection against double charges
documents with a qualified e-signature — invoices and acts are generated automatically and signed under the Ukrainian DSTU-4145 standard
everything in one place — websites, domains, email, files, and payment history in a single account
Clients serve themselves while you see the full picture in the back office — no manual routine.
#1
SaaS platforms from scratch
Clients Express is a multi-tenant SaaS I built end to end:
online booking with a calendar and a public widget
billing with plans, a wallet, invoices, and LiqPay
company landing pages on their own subdomains
Telegram bots and an AI assistant inside the platform
One product serves many companies at once — each in its own isolated space.
#2
Internal tools and custom engines
Not every task needs a “platform.” Sometimes you need a precise tool:
Notes — a self-hosted note-taking app with a built-in AI assistant that searches, creates, and edits notes through chat
LANDING.EXPRESS — a product landing page running on its own lightweight PHP engine with no CMS or frameworks
AI Talks — a web app where AI agents hold autonomous voiced conversations with each other
They all share one thing: minimal dependencies and full control over the code.
#3
Architecture, security, speed
A web app lives for years, so the foundation matters more than features:
two-factor authentication, passkeys, and bot protection for forms
signature verification for every payment webhook
caching (Redis) and optimization for real load
action audit and event logs — you always know who did what
That’s how you get solutions built to last for years — without midnight “everything is down” calls.
#4
Who this is for
businesses that have outgrown ready-made services and spreadsheets
companies with processes no boxed product covers
founders who want to turn an idea into a SaaS product
Examples of implemented solutions can be viewed in the portfolio section or learn more about other services.
To sum up
Ready-made services are great for starting and poor at bending around non-standard processes. A custom web app costs more upfront, but it’s an asset you own — one that grows with your business. If you feel your business no longer fits into off-the-shelf tools — get in touch: you work directly with the engineer, no middlemen.
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Hi! I'm the KAPLIA.PRO virtual assistant! I can tell you about our services, portfolio projects, ballpark pricing, and how we work — from websites and eCommerce to web apps, CRMs, bots, and AI agents. Ask away!
