Sviat O.

I audit and harden AI-built SaaS, then run engineering as a fractional CTO. Top Rated Plus | 100% Job Success | $200K+ on Upwork. Lead engineer of a German AI image and video SaaS for 3 years. Founder of a profitable product with 211 paying customers. The SaaS is a multi-tenant platform used by event organizers and brands. I own its architecture, delivery and production reliability: AI image and video generation, team permissions, CRM, analytics and GDPR compliance. Campaigns on it reach 30-60% visitor usage. The profitable product is a photo tool for residence-permit applications that I built and run solo (both are in the Portfolio). WHAT I DO FOR FOUNDERS • Codebase audit, fixed price, one week. You get a written report: tenant isolation and auth, database and migrations, background jobs and webhooks, billing, cloud spend, test coverage, and a ranked list of what to fix before your next 10 and next 100 customers. Useful on its own, with or without me afterwards. • Hardening. I take an AI-generated or contractor-built app and make it hold up: idempotent jobs, validated LLM outputs, proper roles and row-level security, Stripe edge cases, migrations that do not lose data, e2e tests that catch regressions. • Fractional CTO retainer. Weekly roadmap and PR review, architecture decisions in plain English, hiring help when you need a second engineer. You work directly with me; nothing is subcontracted. • AI media pipelines. Image, video and voice generation in production: Replicate, OpenAI, Gemini, ElevenLabs, and programmatic video with Remotion on AWS Lambda. Example: a tool that renders a personalized sales video per prospect from one command. HOW I WORK WITH AI CODING TOOLS I use Claude Code daily, behind strict test suites, codebase rules and MCP tooling, so generated code fits the project instead of fighting it. A past client: "He put real thought into working with AI coding tools, setting up rules and structure in the codebase so the generated code actually fit." PROOF • Upwork Top Rated Plus, 100% Job Success, $200K+ earned, 23 contracts. • Average contract 180+ hours, longest 1,600+ hours and still running. • Founder of a profitable SaaS, so I care about unit economics and shipping, not over-engineering. • "Sviatoslav is one of the few I kept on for close to a year... When he handed his work over, he documented every step so nobody was left guessing." Based in Poland (EU, GDPR), working in CET, overlapping US mornings. Stack: TypeScript, Next.js, React, Node.js, NestJS, PostgreSQL, Supabase, MongoDB, AWS, Vercel, Stripe, OpenAI, Anthropic, Replicate, Remotion, Playwright. Send me a note on what is breaking or what you are about to launch, and I will reply with how I would approach it.