App Builder

Ruby Growth Labs, LLC; United States; Remote; USD 120,000 - 170,000; Full time

Job summary

Ruby Growth Labs, LLC seeks a craft-focused engineer/designer who loves web and mobile apps. You design screens and flows, build in Rails for web and Swift/Kotlin for mobile, and you’ll ship every day with AI tools to accelerate delivery.

You will work closely with the founder and GM, own the user experience end-to-end, learn the business side, and contribute to product decisions from day one in a fast-paced, user-centric environment.

Job description

You design and build web and mobile apps that people enjoy using. You know the medium inside out,and you can't stop thinking about what it could do next.

Why this role exists

We stopped writing code by hand. A working version of an app now takes days, not months.That means the people who matter most are the ones who know what a great app feels likeand can get there fast.

Our GMs run each product as a business. You're the one who makes it beautiful and makes it work.You sit next to the GM and our founder, you ship every day, and you learn the business side as you go.

Do this well and the GM seat is the next step.

What you'll do

• Design the screens and the flows. Onboarding, the core loop, the paywall, the empty states. In Figma or straight in code, whichever gets to a real answer faster.
• Build them. Rails on the web, Swift and Kotlin on mobile, with AI tools doing the heavy lifting. Built to hold up in production and the app stores.
• Ship something every day. Put it in front of real users, watch what they do with it, and change it.
• Make it engaging. The detail that makes someone come back tomorrow. Motion, feedback, speed, the moment it feels alive. You own that.
• Direct agents for the grind. Tests, migrations, boilerplate, the fifth variant of a screen. You give the brief and review the result.
• Learn the business side. Sit in on customer conversations. See how the funnel and the revenue model shape what gets built.

Who you are

• You're obsessed with web and mobile as a medium. You notice when an app feels great, you can explain why, and you have a list of things you want to try.
• You design. Layout, type, motion, hierarchy. You have taste and you can show it in things you've shipped, not just mockups.
• You build. Rails on the web, Swift and Kotlin on mobile, and you've shipped to the App Store, the Play Store, and real users on the web. Years of it, not a bootcamp.
• You ship with AI tools. Claude Code, Cursor, or whatever is fastest. You've used them to build real things, not just demos.
• You care that it works for the person using it. You'd rather watch one real user than read ten opinions.
• You work independently and stay focused. You decide what matters today, do it, and show the result.
• You want the business side. You're curious how an app makes money and you want to learn to run one.

What this isn't

• A designer role where you hand mockups to developers.
• A developer role where someone else decides how it looks.
• A ticket queue. You'll get a goal and a customer, not a backlog.

How we work

Talk before you build

Every engagement starts with customer conversations, run with the founder, before a line of code. We find what people will pay for first.

Build the smallest thing that works

A real app, in weeks, built to hold up in production and the app stores. Not a prototype that breaks the day after the demo.

Show, don't ask

We don't ask customers what to build. We put a working version in front of them and watch what they do with it.

Not a feature. A decision about what to build next, backed by what a customer said and did.

Show us something you built that people enjoy using

The application asks for apps you've shipped, an app you think is beautifully built, and what you've made with AI tools lately.Links beat descriptions.