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Dmitrii Lemin

@dmitriilemin

Senior frontend engineer at Tokentech building fintech account flows and Biassemble, an evidence-grounded LLM reasoning-audit system.

Thailand

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What I'm looking for

I'm open to remote senior frontend, full-stack, and AI product engineering roles. I care about shipping features that map to real business needs, keeping tech debt from strangling velocity, and building interfaces where users always know where they are and what happens next.

At Tokentech, I own authentication and account flows for a crypto trading platform, including signup, KYC, 2FA, and API keys. I’ve also improved session reliability in live trading and implemented a redesigned user cabinet.

On my Biassemble project, I’m building an LLM-powered reasoning-audit system that detects cognitive biases in text with evidence grounding. It combines a React SPA, a Fastify and TypeScript API, semantic retrieval over pgvector, and quality checks backed by golden datasets.

Earlier, at Jetlyn, I built an IT request workflow application and led frontend team growth from one to three engineers. I’m open to remote senior frontend, full-stack, and AI product engineering roles, and care about shipping features tied to real business needs while keeping interfaces clear and tech debt manageable.

Experience

Work history, roles, and key accomplishments

Current

Frontend Developer

Current

Tokentech

Mar 2025 - Present (1 year 7 months)

• Owned core authentication and account domain (signup, KYC, 2FA, API keys), working with REST APIs and GraphQL to ensure stable user access across critical platform flows and support user activation
• Implemented redesign of the user cabinet, simplifying account management flows and increasing conversion from signup to first transaction
• Diagnosed and resolved edge-case issues in aut

Senior Frontend Developer

Newton Technology

Dec 2023 - Feb 2025 (1 year 2 months)

• Delivered features for a live trading platform, improving stability of core flows and reducing user-facing issues
• Applied a custom TanStack Query DSL to unify server/client state, reducing inconsistent data handling and improving reliability of user interactions
• Standardized API interaction patterns, improving maintainability and reducing friction in feature development
•

Senior Front End Developer

Swift Invention Inc

Dec 2022 - Nov 2023 (11 months)

• Contributed across multiple products in a startup environment, supporting rapid iteration and product validation
• Built frontend applications from scratch, enabling fast delivery of new product features
• Developed reusable UI components and patterns, improving development efficiency and consistency
• Implemented list virtualization and optimized rendering strategies, improvi

Sr. Front End Developer

Jetlyn

Mar 2020 - Nov 2022 (2 years 8 months)

• Built frontend application from scratch for IT request workflows, enabling structured multi-step approval processes
• Designed and implemented complex state-driven flows, reducing manual coordination and improving process efficiency
• Led frontend team growth from 1 to 3 engineers, increasing team delivery capacity
• Owned task breakdown, code reviews, and implementation consi

Sr. Front End Developer

Purchasing Platform

Jul 2018 - Feb 2020 (1 year 7 months)

Worked on a B2B wholesale marketplace for facility and property maintenance companies — product covered catalogue browsing, search, and order management.
Worked in a cross-functional team of 2–4 frontend engineers alongside backend, analytics, design, and PM. Responsibilities included feature development, ongoing maintenance, code reviews, and test coverage.
Key contributions: helped a full applic

Front End eveloper

Eastwood lab

Mar 2015 - Jun 2018 (3 years 3 months)

Developed, maintained and improved SPA working with Transparency.js
Created and implemented use of Unit Tests with Karma and Jasmine
Built mobile version application
Improved rendering time characteristics of application
Middle management, assigned tasks among team
Performed code review
Developed and improved custom architecture SPA created with native JS

Front End Developer

q-cis

Feb 2014 - Feb 2015 (1 year)

Built responsive and adaptive websites
Developed, maintained and improved SPA based on AngularJS
Created markup application with LESS and Bootstrap

front-end programmer

Crowd Lab

Mar 2013 - Sep 2013 (6 months)

Built responsive and adaptive websites
Developed, maintained and improved SPA with AngularJS
Developed and improved markup application with Stylus

back-end / front-end programmer

freelance

Oct 2012 - Feb 2013 (4 months)

Built responsive and adaptive websites
Maintained and improved back end with php

http://oko.plys.kiev.ua/
http://www.rustouroperator.ru/

php / front-end programmer

Anatoly Popel Studio

Sep 2011 - Sep 2012 (1 year)

Built and improved custom websites with Joomla, Wordpress, Kohana
Maintained and improved back end with php

1. http://a2k.com.ua/
2. http://akuloff.com.ua/
3. http://www.anabaston.com/
4. http://ansmep.com.ua/
5. http://bayviewinnovations.com/ru
6. http://www.feel-good.com.ua/
7. http://kapitonenko.com/
8. http:///gertsogsky.com
9. http://isa-2012.org.ua/ru/
10. http://www.zelks.ru/

php-developer

freelance

Mar 2009 - Aug 2011 (2 years 5 months)

1) Create sites with Joomla + virtuemart
2) Create sites with на Wordpress

Projects:
1. http://non.in.ua/
2. http://apartmentcity.eu/
3. http://ukrshop.com/ (сопровождение)
4. http://svetamakarova.com/
5. http://click-poll.com.ua (дароботка)
6. http://oko.plys.kiev.ua/ (доработка)

php-developer

http://artix.com.ua/

Dec 2008 - Feb 2009 (2 months)

1) Create web sites with cms: joomla, small nuke, Frog CMS
2) Setup and modernize virtuemart

1. http://nokianshop.com/
2. http://knauf.kiev.ua/
3. luxsvadba.com.ua
4. http://reunov.com.ua

Partner Account Manager

Flysoft

Jan 2006 - Oct 2008 (2 years 9 months)

Деятельность:
1) Работа с первичной документацией (счета/акты)
2) Общение с партнёрами
3) Сортировка контента
4) Написание клиент-серверной программы «Учёт документации». Язык: Delphi
5) Тестинг java-приложений для мобильных