Senior Front-End / Product Engineer · React / TypeScript

Hello, I'm Brian

Brian Shimkus, Senior Front-End / Product Engineer

Senior front-end and product engineer with 13 years delivering customer-facing software, integrations, and regulated financial workflows. Recent independent work extends that foundation into Python, FastAPI, and applied AI through an evaluated ticket classifier and two completed real-time portfolio builds.

View Resume

Available for product engineering roles · Chicago, IL · Remote OK

Latest Writing

Blog

Deep dives into building AI applications, enterprise integrations, and customer-facing products. From architecture decisions to production deployment.

Document Extraction Day 5: A Quote Is Not Proof

Document Extraction Workbench · Day 5

A quote on the page is not proof the total is right

Invoice 1 passed with no issues. A quote I invented was flagged. Invoice 3 stored 9.00 while the page says 90.00, and that one still passed. Day 5 of building a document extractor.

Oct 20, 20266 min read
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Run Explorer Day 4: One Filter, One Cache Entry

Run Explorer · Day 4

One filter should not wear another filter’s data

The table now requests one page through a mock API. A slow failed request cannot overwrite a newer succeeded filter because each result has its own cache key.

Oct 18, 20266 min read
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Ask TanStack Query Day 4: The Model Stopped Guessing

Ask TanStack Query · Day 4

The model stopped guessing

The same kind of question had to be answered from the stored cards, and each answer had to name its page. One came back right, one honest and incomplete, one a correct refusal. Day 4 of building a docs assistant.

Oct 16, 20264 min read
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Where I've Been

Experience

Independent Product Engineer

Dec 2025 – Present

Insolla (Consulting and portfolio development) · Chicago, IL

  • ›Delivered an automated content pipeline that cut a business owner’s weekly workflow from 8 hours to 10 minutes.
  • ›Built Ticket Triage, comparing keyword rules with structured OpenAI outputs across labeled development and holdout examples.
  • ›Built Planning Poker and Live Auction, two real-time TypeScript applications focused on resilient connections, authoritative state, accessibility, and testing.

Lead Front-End Developer

Aug 2025 – Dec 2025

TerraFort (Freelance)

  • ›Led design and development of an early-stage web and mobile platform from concept through delivery.
  • ›Owned vendor evaluations and scoped third-party and AI integrations with UX, product, and backend teams.

Senior Front-End Developer

Jul 2024 – Jun 2025

OCC (Contract) · Chicago, IL

  • ›Ran weekly stakeholder sessions at a systemically important financial market utility, aligning goals, demonstrating progress, and resolving questions across workstreams.
  • ›Delivered React and TypeScript solutions from Figma through testing, QA, and production.
  • ›Implemented Mock Service Worker to unblock front-end development from backend dependencies.

Lead Front-End Developer

Oct 2020 – Jan 2024

Marex · Chicago, IL

  • ›Led digitization of broker and trader onboarding, replacing a compliance-heavy paper workflow with an end-to-end digital process.
  • ›Partnered with compliance, operations, and trading teams to scope rollouts and support adoption.
  • ›Integrated the DocuSign API across products to support digital document signing.
  • ›Led a five-person front-end team and designed and ran the team’s internship program.

Earlier Experience

  • Senior Front-End Developer · Walker & Dunlop (Contract)2020
  • Senior Front-End Developer · ICF2019 – 2020
  • Front-End Developer · TransUnion2018 – 2019
  • UX Architect & Front-End Developer · R1 RCM2016 – 2018
  • Front-End Developer · TimeZoneOne (Contract)2015 – 2016
  • Junior Front-End Developer · Kohactive2013 – 2015

What I Know

Skills

Front-end first, with the integration and applied AI work that customer-facing, regulated products need.

Product Engineering

  • React
  • TypeScript
  • Next.js
  • Vue.js
  • Accessible interfaces
  • Design systems
  • Storybook
  • Testing
  • QA
  • WebSockets
  • Playwright

Integrations & Workflows

  • REST APIs
  • Webhooks
  • Salesforce
  • DocuSign API
  • OAuth 2.0/JWT
  • Contentful CMS
  • Workflow automation

Customer & Technical Delivery

  • Discovery
  • Workflow mapping
  • Solution design
  • Technical demonstrations
  • Stakeholder alignment
  • Technical handoffs

Applied AI & Retrieval

  • OpenAI API
  • RAG
  • Embeddings
  • Vector search
  • Structured outputs
  • Source-grounded answers
  • LLM evaluation
  • Human review

Python & Data

  • Python
  • FastAPI
  • Pydantic
  • PostgreSQL
  • pgvector
  • pytest

On My Bookshelf

Currently Reading

AI Engineering: Building Applications with Foundation Models

Chip Huyen

A guide to building real applications on top of foundation models.

Mastering Technical Sales: The Sales Engineer's Handbook

John Care and Aron Bohlig

A handbook on technical sales and the role of the sales engineer.

What People Say

Testimonials

Brian and I worked together on the User Experience team, where he was brought in to assist with front end development of our UIUX projects. He did a great job of quickly jumping in to the mix to work on several of our internal projects, bringing a willingness to learn and a positive attitude to every project. He is also very eager to suggest new approaches to projects and brings an innovative, forward-thinking mindset. He is a talented, energetic and very enthusiastic developer and would be a great asset to any team.

Mark Coleman

User Experience Team Colleague

Brian is a hard working & focused user interface and user experience developer. In our time working together at R1, Brian was consistently dedicated and focused on complex projects, often times putting in significant extra work to help the team meet deadlines. He worked equally well with local teams in the office as well as teams based in India. Good teammate that will help you bring your UI/UX to the next level.

Shane Colley

Colleague, R1 RCM

From LinkedIn, earlier in my front-end engineering career.