Christian Schlensker — Principal Frontend/Design Engineer

Profile

I'm a principal frontend/design engineer with 20+ years of experience turning ambitious ideas into polished products—from zero-to-one startups and founder-led prototypes to customer-facing platforms serving millions.

I work at the intersection of product, design, and engineering. I've been the first engineering hire, a solo designer/developer, a consultant, a frontend platform lead, and a principal engineer—giving me the range to move from rapid product discovery and hands-on implementation to architecture, design systems, high-craft interfaces, developer experience, and the practices teams need to scale.

Today, I'm especially focused on AI products and agent-enabled engineering: making codebases easier for humans and coding agents to understand, modify, test, and extend through clearer architecture, stronger conventions, better documentation, faster feedback loops, safer refactors, and implementation patterns that give teams more leverage.

Skills

Strength

Frontend architecture

HTML / CSS / Web Animation

Agent Harness Engineering

Typescript/Javascript

React.js and Next.js

D3.js

React Native

Algorithms and Big O

Ruby / Rails

iOS / Objective-C / Swift

Figma & Adobe Creative Suite

Work history

Present

Principal Fullstack Web Engineer

Endgame Labs

Oct 2023 - Present

San Francisco, CA

As a principal web engineer at Endgame, I lead the architecture and establish coding standards for modern web application development, with expertise in Next.js, React, TypeScript, and D3. Collaborating closely with the CEO and Head of Design, I prototype and help inform tactical approaches for new product directions while maintaining and enhancing the internal design system to ensure design consistency and efficiency. I also work on improving developer workflows and project management as well as refining testing processes and coding standards, and I create comprehensive implementation plans to streamline project execution and support the broader engineering team.

Web Animation
React.js
Typescript
Next.js
Framer Motion
GraphQL
Python

Highlighted projects

Streaming chat UI and rich markdown output

Oct 2023

Freelance Software Engineer

Foxy Blocks

Oct 2021 - Oct 2023

San Francisco, CA

As a freelance consultant, I delivered high-quality web solutions for clients ranging from startups to established companies. I specialized in crafting dynamic and visually engaging experiences using web animation, WebGL, D3, Sanity.io, Web3, and Pixi.js. Projects typically spanned 1-3 months, with one extended engagement lasting 8 months.

Typescript
Web Animation
Next.js
Pixi.js
WebGL

Oct 2021

Design Engineer on Square Banking team

Block

Mar 2020 - Oct 2021

San Francisco, CA

Responsible for implementing and maintaining the design system components for the Square Banking and Capital products used by 60+ engineers and designers. I was also in charge of developing and maintaining all public marketing web pages for the Square Banking launch and Square Capital. These projects have high quality standards, feature rich animation, and are visited by millions of users.

Web Animation
Figma (Software)
TypeScript
GatsbyJS
Svelte
React.js
storybook

Highlighted projects

Square Banking Launch

Mar 2020

Senior Frontend Engineer for Square appointments app

Block

Sep 2018 - Mar 2020

San Francisco, CA

- Lead engineer for frontend developer experience and infrastructure
- Lead engineer on Instagram partnership integration

Web Animation
Figma (Software)
TypeScript
GatsbyJS
Svelte
React.js
storybook

Aug 2018

Lead Frontend Engineer

Bugsnag

Mar 2016 - Aug 2018

San Francisco Bay Area

- Leader of frontend product development with React.js, D3.js
- Maintainer of frontend infrastructure and build tooling (jest, webpack, flow, storybook)
- Technical contributor to company blog, conference evangelism and community outreach

Webpack
JavaScript
CoffeeScript
Developer Relations
Mentorship
React.js

Mar 2016

Full Stack Engineer

Bloc

Apr 2013 - Mar 2016

San Francisco, CA

As Bloc's first engineering hire, I led technical direction and helped establish engineering practices as the team grew to 8 engineers within a 30-person company. I developed and led the enrollment and billing management systems, built and maintained the scheduling system for one-on-one mentor sessions, and maintained the full-stack architecture for interactive coding exercises across the 12-week online bootcamp.

Technical Leadership
Ruby on Rails
Angular.js
Architecture
Mentorship

Apr 2013

Design Engineer

Pinchit

Aug 2011 - Apr 2013

San Francisco Bay Area

At seed-stage Pinchit, I worked across design and engineering as the company evolved from hosted events and daily deals into a local discovery platform for content, events, and restaurants. I was the sole designer and developer of the native iOS application, taking it from zero to one, and contributed across the full web product as a full-stack engineer using Ruby on Rails and Backbone.js. As an IC, I also led many of the product's technical decisions.

iOS
Objective-C
Ruby on Rails
Backbone.js
Product Design

Mar 2011

Web Designer

TAG

Oct 2007 - Mar 2011

At TAG, a four-engineer software consultancy, I led web design, CSS, and frontend development for clients including Microsoft and the State of Indiana. I designed and built web and software interfaces using HTML, CSS, JavaScript, and ASP.NET with C#, including the online community website for Microsoft Office 365.

Web Design
HTML
CSS
JavaScript
ASP.NET
C#

Aug 2006

Graphic Design Intern

ESC Promotions

Nov 2005 - Aug 2006

While a senior in high school, I worked as one of two designers at ESC Promotions, producing approximately eight custom plastic fundraiser discount-card designs per day for schools and similar organizations nationwide. Each card paired artwork for the participating school, band, or sports team with discounts from local businesses, giving those groups a product they could sell within their communities to raise money.

Graphic Design
Print Production