Work

After Hours.

Small tools I build when the day is done. Pick one, or clicktap a lit window.

TelewordA Telegram bot for learning EnglishTelegram bot ↗

cad-helperPlain text in, a CAD drawing outExperiment ↗

# Serge Vinterman (vinterman) Builder and quality seeker: product engineer with a QA Lead and SDET background. Sofia, Bulgaria. - LinkedIn: linkedin.com/in/serge-vinterman - Email: vintermanserhii@gmail.com ## Current project **Limitless**: Product Engineer, 2025 — now, Prediction markets · full-time - Ships features end to end: idea, design, code, tests, release, support - Fixes bugs across frontend and backend - Daily AI work: custom harnesses and pipelines, knowledge base, skills, debugging and monitoring, release gates - Manual and automated tests: new features, custom trading core (CLOB, AMM, neg-risk, ladder markets, RFQ, parlays) - Iterates test automation (frontend, backend, integration, load) for several production releases a day ## Previous projects **Skipr**: QA & AQA Lead, 2024 — 2025, Patented security protocol · full-time - Built QA from zero: process, docs, dashboards, automation, QA team hiring - E2E automation: web (Playwright), mobile (Appium), API (TS + Axios), load (k6 + Artillery), GitHub Actions CI/CD - Real iOS and Android device farms (LambdaTest), flaky-test hunting, scheduled regression with alerting - Security for gov and enterprise clients: VPN leak tests (DNS, IP, traffic), no-data-collection checks, SAST; quality demos and reports for investors - Wrote features and fixed bugs in product code (Node, Flutter) **Turbo Stars**: Senior QA & AQA Engineer, 2022 — 2024, Betting · full-time - Organised QA on a microservices platform with dense math logic - UI framework (Playwright) and API framework (TypeScript, Axios, Chai), GitLab CI/CD - API testing, manual (Postman, Swagger) and automated (own framework); load tests on critical scenarios (k6) - Jira productivity dashboards and charts for a big team - Onboarded and mentored 2 QA engineers **Web33**: AQA Engineer, 2020 — 2022, DeFi · full-time - Built test automation from zero for 15+ client projects - Web (Selenium) and mobile (Appium, Android emulators) suites for client DeFi apps - Load and stress tests against bot traffic and multi-accounting: Gatling (API), Artillery (WebSockets) - Self-hosted test pipeline: Jenkins → DockerHub → Helm → Argo CD → Kubernetes - Monitoring and support of delivered client projects: Prometheus, Grafana, alerts **Crypto projects**: Builder, node operator, tester, 2019 — 2021, Freelance - Testnet bug hunting and reports for early-stage projects - Ran early validator and full nodes on own and rented hardware - Built and ran own servers: overclocking, uptime, repairs - Wrote autotests for projects, whale-wallet checkers and trading bots: spot, futures, cross-exchange, copy-trading ## Qualifications ### AI - Agents: Harnesses, tool calling, orchestration, multi-agent, LangGraph, MCP servers - Evals: Golden datasets, LLM-as-judge, regression evals, CI release gates - Observability: Tracing, cost and latency monitoring - Safety: Guardrails, hallucination checks, prompt injection tests - RAG: Embeddings, retrieval, vector databases - Context engineering: Agent skills (SKILL.md), system prompts, structured outputs - Multimodal: OCR, speech-to-text (Whisper), text-to-speech, VLM, image/video generation - Models: Claude, GPT, Gemini, Grok, DeepSeek, Kimi, open-source (Qwen, Llama, uncensored Gemma) ### Quality - Web: Playwright, Cypress, Selenium, WebdriverIO - Mobile: Appium, Android, iOS, emulators, simulators, farms (LambdaTest, BrowserStack) - API: Postman, Swagger, OpenAPI, REST, GraphQL, WebSockets - Performance: API (k6, JMeter, Gatling), WebSockets (k6, Artillery) - Security: Network leakage tests, SAST (DefectDojo), Claude Security - Blockchain: Foundry, Tenderly, Synpress - Traffic: DevTools, mitmproxy, Fiddler, Charles, Wireshark - Approaches: Page Object, risk-based, exploratory, data-driven, BDD (Cucumber), shift-left, cross-platform, regression, accessibility - Test design: ECP, BVA, DTT, EG, STT, PWT - Documentation: Test plans, test cases, checklists, bug reports, test reports, acceptance criteria, RTM, dashboards - Test management: Jira, Xray, Zephyr, TestRail, Notion, Confluence - Process: SDLC, STLC, Agile, Scrum, Kanban - Leadership: Hiring, mentoring, estimation ### Development - Backend: TypeScript, Node.js, Python - APIs & realtime: REST, GraphQL, webhooks, WebSockets, SSE - Databases: SQL: PostgreSQL, MySQL, NoSQL: Firestore, MongoDB, Redis - Queues: Kafka, Pub/Sub, RabbitMQ - Frontend: React, Next.js ### Cloud - Cloud: Google Cloud (certified), AWS, Hetzner, Akamai - IaC & GitOps: Terraform, Argo CD - Containers: Docker, Kubernetes, Helm - CI/CD: GitHub Actions, GitLab CI, Jenkins - Networking: VPN, TCP/IP, DNS, routing, firewalls, traffic analysis - Systems: Linux, Windows, macOS - Observability: Logs, metrics, load, agent monitoring - Blockchain infra: Validator and full nodes, testnets ### Design - Product design: Wireframes, user flows, high-fidelity UI - UI: Typography, grids, visual hierarchy - Research: References, surveys, user interviews - Prototypes: Figma, code, AI-assisted - Design systems: Tokens, components, guidelines - Accessibility: WCAG, contrast, focus states, semantic markup - Brand: Identity, illustration style, personal brand systems ## Certificates - Associate Cloud Engineer (Google): https://www.credly.com/badges/d63ed157-3b60-4a11-9b10-917aea45c1f7/public_url - Fundamentals of OS (Udemy): https://udemy-certificate.s3.amazonaws.com/image/UC-2e314c58-edf5-4dce-b1e5-4be4f848d5a5.jpg - Master Redis, from beginner to advanced (Udemy): https://udemy-certificate.s3.amazonaws.com/image/UC-fb8eaf65-5308-495c-b214-49eab2a1a508.jpg - Fundamentals of Database Engineering (Udemy): https://www.udemy.com/certificate/UC-bf7376b1-83c7-41ea-8b7b-c0d61ad310a8/ - Realtime Backend System Design with WebSockets (Udemy): https://udemy-certificate.s3.amazonaws.com/image/UC-3f2660a3-f970-4b5e-a69b-adcf4d653cdd.jpg - Fundamentals of Backend Engineering (Udemy): https://udemy-certificate.s3.amazonaws.com/image/UC-5c43d135-7445-4700-8551-a9da0a48a27d.jpg - Next.js & React, the complete guide (Udemy): https://ude.my/UC-eff030f3-124c-4bf3-90b2-82cc3ced6b6c - Python Application (Stepik): https://stepik.org/cert/1514701?lang=en - Python Core (Sololearn): https://www.sololearn.com/Certificate/CT-ANNKBBSU/png - SQL (Sololearn): https://sololearn.com/certificates/course/en/25949305/1073/landscape/png ## Languages - English, Bulgarian, Russian, Ukrainian ## After hours - Teleword: Telegram bot for learning English · https://github.com/vinter-man/teleword - cad-helper: Plain text → CAD drawing · https://github.com/vinter-man/cad-helper