Custom application development — and a senior developer for your team

Option 1 — End-to-end custom app development

You have a product to build and no in-house engineering team — or a team that does not have the bandwidth to take on something new. I take it from idea to a shipped product: discovery, architecture, design, build, deployment, and the iterations that come after.

Web apps, mobile apps, internal tools, client portals, B2B systems. I build on modern, boring-where-it-matters stacks (Rails, Node, Vue/React, Postgres) so that whoever maintains the code after me — your future team, another contractor, me — has an easy time.

  • Customer-facing web and mobile applications
  • Internal tools, dashboards, and admin systems
  • Client portals and B2B platforms
  • Greenfield products from idea to MVP and beyond

Option 2 — Embedded into your development team

You already have a team. It is shipping, but stretched thin. There is one initiative you keep pushing to next quarter because nobody has the time or the seniority to own it. Or you need a steady senior hand on backend, architecture, or a hard migration.

I join as a contractor — your standup, your tools, your codebase, your review process — typically 3 to 6 months, part- or full-time. I own real features, not side projects. I pair with your developers, push code through review, and raise the bar on what ships. When the engagement ends, your team is stronger and your code is cleaner.

  • Senior capacity without committing to a permanent hire
  • Ownership of features end to end, not just tickets
  • Code review, mentoring, and architectural input for your team
  • Honest outside perspective on bottlenecks and tech debt

How a build runs

No 200-page specifications that go stale in a month. I start with a short discovery — who it is for, what it must do, what wins matter most. I propose architecture, scope, and price up front, then deliver in short cycles so you see the product taking shape and can adjust direction early.

You work directly with me. The person designing the architecture is the person writing the code. No agency middle layer, no junior swap-out after kickoff.

  • Discovery and architecture proposal up front
  • Working slice in production within weeks
  • Short delivery cycles — you see progress, you react
  • Tested, reviewed, documented code (ex-GitLab standards)

How embedding runs

I agree with you on the target — an initiative, a system, a chunk of the roadmap — and on how I plug into your team. I onboard fast: most of my engagements have me reviewing PRs in week one and owning real work by week two.

I match your stack, your conventions, and your process. I am not there to redesign your team; I am there to add senior firepower where you need it. When the engagement ends, the work transfers cleanly because it was written for your team from the start.

  • Clear initiative and success criteria agreed up front
  • Fast onboarding — productive in the first weeks
  • Code matches your conventions, not mine
  • Clean handover at the end of the engagement

What you get either way

Production-grade engineering from someone who has shipped at scale. Code that future developers will not curse. A senior collaborator who tells you the truth about scope, trade-offs, and what is actually worth building.

  • 15 years of production engineering experience
  • Direct collaboration — no handoffs, no account managers
  • Clean, documented, testable code
  • A solution — or a teammate — that scales with you

Building something, or hiring a senior?

Tell me what you are working on. I will help you figure out whether you need a full build, an embedded developer, or something smaller — and whether I am the right person for it.

Start a conversation
Jarka Košanová

Contact

Do you have a problem and no clear technical solution yet? Get in touch. I will find the simplest workable path with you, and you can book a no-obligation consultation right away.