20+ years building business systems · Web · Mobile · Desktop · Database · APIs · Remote · fluent in US / EU timezones · Based in Chicago, USA · worldwide delivery

Software built exactly for how your business runs.

Web apps, mobile apps, internal tools, custom databases, back-office systems. When off-the-shelf almost fits but not quite — or when you need something that doesn't exist yet — I design and build it, end to end. One engineer, direct accountability, production-grade code.

You need something specific that off-the-shelf doesn't do.

Every business has workflows that don't fit standard products. A spreadsheet held together by macros. A legacy Access database nobody touches. A CRM that's 80% right but misses the one thing your operation depends on. A mobile app nobody wants to build because the market is too small for a product.

This is where custom software earns its cost. Done right, it disappears into how you work — nobody thinks about it, it just runs. Done wrong, it becomes the thing everyone complains about. The difference is who builds it and how they work.

I've been doing this for twenty years. Web applications, mobile apps, desktop tools, internal dashboards, custom databases (yes, even Microsoft Access), production APIs, scraping pipelines, integrations between systems that weren't meant to talk to each other. Whatever shape the problem takes, I've probably built something like it before.

You should call me if:
  • A vendor quoted you $80k+ and six months for something you suspect is simpler than that
  • You're running critical operations in spreadsheets / Access / legacy tools and it's cracking
  • You need an internal tool that no SaaS product will ever build because your niche is too small
  • You have a clear workflow in your head but no one on the team can translate it into working software
  • Your current system works but the company outgrew it and the vendor can't keep up
  • You need a mobile app, a web portal, a back-office tool, and you want one person to own all three

Whatever the problem needs — I build it.

Custom web applications

Internal tools, customer portals, dashboards, admin panels. PHP, Node.js, Python — chosen for the job, not the fashion.

Mobile applications

iOS and Android. Native where it matters, React Native / Flutter where it's the right tradeoff. API backend included.

Desktop & database tools

Yes, including Microsoft Access — or modernizing off it. Custom databases (PostgreSQL, MySQL, SQLite) designed around your data, not bolted on.

APIs & back-office systems

The plumbing nobody sees — order processing, invoicing, reconciliation, document generation, scheduled jobs, queues, webhooks, integrations.

Integrations between systems

Wire together CRMs, accounting, e-commerce, payment processors, shipping, compliance tools. Make the stack you already have work as one.

Full source code & documentation

Everything you commission is yours from day one. Clean code, deployment runbooks, docs your team (or future contractor) can pick up.

Five phases, measured deliverables, no surprises.

01
1-2 weeks

Discovery & scope

My part
Working sessions to map what you actually do today and what needs to exist. I watch real workflows, not job descriptions. Understand the data, the constraints, the people.
Your part
Access to current systems, a few hours of walkthroughs, and straight answers about what's working and what isn't.
Deliverable
Written scope document + architecture diagram + fixed-price proposal for Phase 1
02
1-2 weeks

Architecture & prototype

My part
Design the data model, API contracts, UI wireframes. Build a working prototype of the highest-risk part — typically the thing that will kill the project if it doesn't work. Validate on real data.
Your part
Review the prototype with the team who'll use it. This is the cheapest moment to change direction — feedback here shapes everything that follows.
Deliverable
Working prototype of the critical path + finalized architecture + Phase 2 scope
03
4-16 weeks

Build in phases

My part
Milestone-based implementation with weekly demos. Every feature ships to a staging environment your team can touch. Continuous iteration on real usage.
Your part
Weekly 30-minute review. Test features as they land. Tell me when something is wrong while the cost of changing it is still low.
Deliverable
Working software in production-quality staging, feature by feature, week by week
04
2-4 weeks

Launch & stabilize

My part
Migration from legacy systems (if any), data import, go-live support, bug triage for the first weeks of real use. Smooth the edges where real users meet the software.
Your part
Coordinate rollout with your team. Flag friction early so I can fix it before it becomes habit.
Deliverable
Live system running your actual operations + training materials + runbook
05
ongoing or clean exit

Operate & hand off

My part
Continued maintenance, small features, bug fixes — or a clean handoff to your internal team / another contractor. Your choice.
Your part
Decide the shape of ongoing support that fits your team.
Deliverable
Clean handoff package or retained-engineer agreement

Chosen for the job — never for fashion.

The right stack depends on what you're building, who maintains it after me, and what your team already knows. I optimize for boring, proven tools that won't need rewriting in three years.

Backend
PHP · Node.js · Python · TypeScript · Go
PHP for mature business systems. Node/TS for real-time and modern API work. Python for data-heavy and AI. Go when performance matters.
Frontend
Vanilla JS · React · Vue · HTMX · Tailwind
Whatever your team can maintain. Vanilla for simple admin tools. React/Vue for real SPAs. HTMX when server-driven is enough.
Mobile
React Native · Flutter · Swift · Kotlin
Cross-platform when the business case is two platforms, native when performance or platform features demand it.
Data
PostgreSQL · MySQL · SQLite · Redis · MongoDB · MS Access
PostgreSQL first unless there's a reason. SQLite for embedded and local-first. Yes, still Access when that's what your team uses.
Infrastructure
Docker · Linux · Nginx · AWS · DigitalOcean · self-hosted
Docker for everything. Self-host when it saves money and matches risk tolerance. Managed cloud when it buys real time.
Integration
n8n · REST / GraphQL APIs · webhooks · MQ · cron
n8n for visual automation you want your team to own. Code for anything mission-critical or performance-sensitive.

Who this works for — and who should hire someone else.

Good fit if:

  • You have a specific workflow or system in mind that no off-the-shelf product solves cleanly
  • You can make the buying decision yourself or have short path to the person who can
  • Your budget for phase one is $10k-80k and you understand why fixed-cost, fixed-scope phases beat open-ended hourly
  • You value direct communication with the engineer over an agency org chart
  • You want code and documentation you own — no vendor lock, no black box
  • You are OK with staged delivery — seeing working software in weeks, not a roadmap

Not a fit if:

  • You need a 50-person team or 24/7 shift support — you want an agency or an MSP
  • You're shopping the cheapest bidder on Upwork — quality work has a floor price
  • You want to fully specify the system upfront and pay only when it's 'done' — real software isn't built that way
  • You need it in two weeks end-to-end — honest software takes honest time
  • The project is 3D games, casino / gambling, adult content, or adversarial scraping — not my work

Every engagement scoped individually. Ranges below are typical.

Discovery is free. Phase one is always fixed-price — you know what you're paying before any code is written. Later phases are scoped based on what phase one reveals.

Small
$8k – $25k · 2-6 weeks
Focused internal tool, mobile-first prototype, API integration between 2-3 systems, custom Access replacement, single-purpose web app
Medium
$25k – $80k · 2-4 months
Multi-user business system, full mobile + API + admin, back-office platform, custom CRM, internal dashboard with real-time data
Large
$80k+ · 4+ months
Multi-module system across departments, full-stack platform with mobile + web + admin, complex integrations, multi-year ongoing work
Pricing is always written down before we start. If a fixed-scope phase goes long because of my estimation error, that's on me. If scope grows because of new requirements, we write a new Phase before that work begins. No surprise invoices.

One system. Seven years. Still running.

WebDatabaseProductionComplianceMulti-module
Problem
A manufacturer had outgrown spreadsheets and tried two off-the-shelf systems — both failed on their specific compliance and production-tracking needs. They needed custom software that matched their actual workflow, not a generic template.
Approach
Started with a two-week discovery to map current workflows. Built the warehouse module first (highest pain), then production tracking, then compliance reporting, then order management. Each phase shipped working software that paid for itself before the next phase started.
Outcome
Seven years of continuous delivery. Over 3,000 commits. Still actively maintained. The system runs their daily operations end to end — and the code is clean enough that another engineer could take it over tomorrow.

Dmytro Klymentiev

Independent senior engineer. 20+ years shipping production software across ERP, automation, web, mobile, and infrastructure.

I work as an independent consultant so you always deal directly with the engineer doing the work — no account manager, no junior dev implementing someone else's spec. My background spans mathematics, platform engineering, and two decades of shipping business software that doesn't break.

Today I help founders, operators, and established businesses solve technical problems that off-the-shelf tools can't. I write code I'd be comfortable handing to a stranger, because often that's what happens — every project ends with documentation and a clean handoff path.

Based in Chicago, working worldwide. US / EU / Asia timezones, English primary. Contracts via direct engagement, US entity, or platform (Upwork) — whichever suits your legal setup.

Questions you might have.

What does this actually cost?

Every engagement is scoped individually — no fixed packages. Typical ranges: small focused build $8-25k; mid-size multi-module system $25-80k; large multi-phase work $80k+. Every Phase has a fixed price written down before any code is written.

Can you build a mobile app? Even iOS and Android native?

Yes. Cross-platform (React Native / Flutter) when two platforms is the business case and the UI isn't platform-specific. Native (Swift / Kotlin) when performance or deep platform features matter. I've shipped both.

What about a custom database — Access, SQL Server, PostgreSQL?

Yes, including MS Access. I've both built in Access and replaced it with modern web-based systems. Whatever fits your team's skills and your data's shape. PostgreSQL first for anything new unless there's a specific reason otherwise.

Will you sign an NDA?

Yes. Standard mutual NDA before we share anything sensitive. I've worked under NDA across food & beverage, financial, healthcare-adjacent, and internal manufacturing systems.

Who owns the code?

You do. From day one. Your repo, your servers, your deployment. I write assuming the next engineer to touch it is a stranger — clean code, docs, no proprietary lock-in.

What if you get hit by a bus?

Every project ends with a clean handoff package: architecture docs, deployment runbook, walkthrough of the system. Your team or a new contractor can take over without starting from scratch.

Do you work with clients outside the US?

Yes. I've delivered work for clients across North America, Europe, and Asia. Chicago-based, working across all major timezones, contracts adaptable to your jurisdiction.

How fast can you start?

Discovery call this week. Written scope within 5-10 days. Development start typically 2-4 weeks out depending on current bookings. For urgent work, ask — sometimes there's slack.

Do you do maintenance after launch?

If you want me to, yes — either as a retained engineer (fixed monthly hours) or on-demand. Many clients prefer the retained model because it guarantees availability when something breaks.

What's OUT of scope for you?

3D game development, casino / gambling platforms, adult content, adversarial scraping of sites that don't want to be scraped, SEO-manipulation tooling. Everything else is negotiable.

What I guarantee, in writing.

01

Fixed-scope phases

Every phase has a written scope and a fixed price. You know what you're paying before I write any code.

02

Weekly visible progress

You see working software in staging every week. No waiting four months for a big reveal.

03

Your code, your repo

From day one, everything I produce is yours. No lock-in, no black box, no 'proprietary' anything.

04

Clean handoff always

Every engagement can be taken over by another engineer. Documentation, deployment runbook, walkthrough included.

05

Estimation on me

If I misestimated a fixed-scope phase, the overrun is on me — not a change order on you.

06

Straight answers

If something is a bad idea, I say so. If something is harder than it looks, I say so. If something is simpler, same.

Thirty minutes. No deck. A real conversation.

Discovery calls are free. We'll talk about your actual system — what's broken, what's missing, what a good outcome would look like.

Last updated: 2026-04-23 · by Dmytro Klymentiev