Freelance Design Engineer

About Mass Culture
Mass Culture is a growth media agency. We help mission-driven scale-ups connect brand and performance so they grow faster, more profitably, and with purpose.
About The Role
Mass Culture is a paid media agency and growth partner for mission-driven scale-up brands. We build and run our own client portal: the product our clients log into to see their media plans, budget pacing, cross-channel performance, and the reports we deliver.
We're looking for a part-time engineer to build features in it end to end, and to make them look as good as they work.
What You'll Build
Client-facing surfaces: dashboards, widgets, charts, and the report and deck builders. This is what clients see and react to, and it carries the agency's credibility.
Admin surfaces: the widget builder, plan editor, pacing tools, and configuration panels our team uses every day.
The data plumbing a feature needs: Postgres schema and migrations, server actions, and connector work against ad-platform APIs.
Polish passes on surfaces that already work but don't yet feel finished.
The Stack
Layer
What We Use
Framework
Next.js 16 (App Router), React 19, TypeScript
Data
Supabase — Postgres, Auth, row-level security, BigQuery
Styling
Tailwind CSS v4, Radix UI, a token-based design system
Charts
visx
Editors & interaction
Tiptap, dnd-kit, Zustand
Tooling
bun, Vercel
What We Mean By a Good Eye
You can take a rough spec and produce a surface that looks considered, without being handed a mockup.
You work in the design system rather than around it. Components reference semantic color tokens only, never a raw palette value and never a bare rgba literal, and every dark-mode token has a light-mode counterpart. When the system is missing something, you extend the system.
You notice spacing, alignment, and type hierarchy without being asked, and you care about the difference between 12px and 16px.
You can make a chart readable, not just correct. Charts are where most of our design problems live.
You know the difference between a surface that is done and one that is merely working.
How We Work Together
Asynchronous and autonomous. You pick up scoped work, build it in a branch, and open a pull request. We review and merge. Nothing merges itself.
We write things down. Specs, design docs, and house conventions live in the repo. Read them before you fight them.
Verify your own work. A green test suite is not the bar. We have shipped bugs with a fully green suite, which is why we now expect you to open the page, look at it, and say what you saw.
This codebase is built heavily with AI coding tools. You are welcome to use them and expected to review what they produce as carefully as you would review your own work. Judgment is the job. Typing isn't.
Say when something is wrong, including when we are wrong about it.
Required
What We're Looking For:
Strong React and TypeScript, with real Next.js App Router experience: server components, server actions, and caching behavior.
Comfort with SQL and relational data modeling. You can write a migration and reason about what a query is actually doing.
Work you designed as well as built, in a portfolio or a repo we can look at. A few well-made things beat a long list.
The ability to work independently in an unfamiliar, opinionated codebase and match its conventions rather than impose your own.
Clear written communication. Most of our collaboration is text.
Reliable part-time availability. Consistency matters more than volume.
Nice To Have
Data visualization experience, especially charts built on real, messy data.
Supabase or Postgres row-level security experience.
Experience with analytics, reporting, or BI-style products.
Comfort in design tools, though we will not ask you to produce mockups.
Engagement
Part-time, freelance, remote, and ongoing. Hours and rate are flexible and agreed up front. We start with a small paid scoped project so both sides can find out whether it's a fit before committing to more.
To apply, send a note and a link to something you designed and built.
Mass Culture On Inclusion
We hire great people from a wide breadth of backgrounds, not only because it’s the right thing to do, but also because it makes our work, our company and our communities stronger. Mass Culture is committed to creating a diverse environment and is proud to be an equal opportunity employer. All qualified applicants will receive consideration for employment without regard to race, religion, gender, gender identity or expression, sexual orientation, disability, age, veteran status, national origin or any other federal, state or local protected class.

Work arrangement
Yes