Senior Full-Stack Engineer · Open to new projects

I build apps people love to use.

Hi, I'm Kyrsten Horvath. I love building apps. I help startups and teams design, build and ship mobile and web apps, from the first prototype to the App Store.

Start a project See my work

React
React Native
Expo
TypeScript
SQL
MongoDB

engineer.ts

const engineer = {
  name: "Kyrsten Horvath",
  role: "Senior Full-Stack Engineer",
  focus: ["mobile apps", "web apps", "APIs"],
  available: true,
};

// let's build something good
engineer.contact();

Services

How I can help your team ship.

Available for freelance projects, contract roles and short consulting engagements.

Mobile apps

iOS and Android apps with React Native and Expo, from first prototype to the App Store and Google Play.

Web applications

Fast, accessible front ends and full-stack apps, from first prototype to production release.

APIs and backend

Clean, well-documented services and integrations that scale with your users and your team.

Consulting and code review

Architecture reviews, performance audits and honest technical advice before you commit to a build.

How we'll work together

01
Discover
We talk through your goals, users and constraints, then agree on scope.
02
Design
A lightweight technical plan and milestones, so nothing is a surprise.
03
Build
Short iterations with working software and regular updates along the way.
04
Ship and support
Launch, documentation and a handover your team can run with.

Selected work

Projects I'm proud of.

Featured project

Bellynote

An AI food and symptom journal for iPhone that helps people find their food triggers. Snap a photo of a meal, a nutrition label or a barcode and Bellynote identifies the ingredients and food groups, then lines foods, additives and cycle phases up against symptoms in heatmaps. Sage, a built-in AI assistant, answers questions about your own logs. I built it end to end: the React Native app, a Supabase backend with AI edge functions, subscriptions, Apple Health sync, and a Next.js marketing site, web app and admin dashboard.

React Native
Expo
Supabase
OpenAI
Next.js
RevenueCat

Read case study →Visit bellynote.app →App Store →

Healthly

My first freelance role: helping an AI calorie counter for iPhone and Android get off the ground. I helped the team put better engineering patterns in place and built the app's custom iOS home screen widgets and lock screen complications.

iOS
SwiftUI
WidgetKit

Read case study →App Store →healthlyai.com →

Street Parking

At Launchpoint Dev I led the ground-up migration of Street Parking, a fitness app with 30k+ active subscribers and a 4.8-star App Store rating, from NativeScript to React Native and Expo, carrying most of the rebuild myself. I also built its custom subscription paywall from scratch, with no RevenueCat, handling Stripe, Apple Pay and Google Play.

React Native
Expo
TypeScript
Stripe
NativeScript

Read case study →App Store →streetparking.com →

Pricing

Simple, honest pricing.

Fixed-price packages for most projects, and an hourly rate for everything else. Every quote is confirmed after a free intro call.

Landing page

from$1,500

A focused, single-page site that explains what you do and turns visitors into leads.

Custom design, built for your brand
Responsive on every screen size
Contact form or booking link
Basic SEO and analytics setup
Deployed on fast, modern hosting

Typically 1–2 weeksStart a project

WebsiteMost popular

from$4,500

A multi-page marketing or business site you can grow with.

Up to 6 custom-designed pages
Content you can edit yourself
Blog, portfolio or case studies
Performance and accessibility tuned
SEO, analytics and launch support

Typically 3–5 weeksStart a project

Web or mobile app

from$15,000

A full-stack product, from first prototype to production release.

Product and technical planning
Accounts, payments and integrations
API, database and cloud setup
Testing and CI/CD pipeline
Documentation and handover

Typically 6–12 weeksStart a project

Hourly

$125/hr · Maintenance, bug fixes, small features, code review and consulting.

Book hours

Common questions

How does payment work?

50% deposit to book the project, 50% at launch. Larger projects are split across milestones.

What if I need changes along the way?

Each package includes two rounds of revisions. Anything beyond the agreed scope is billed hourly, and I always check with you first.

What isn't included?

Copywriting, photography and third-party costs like hosting, domains, paid APIs and app store fees. I'll flag anything you'll need before we start.

Who owns the code and the site?

You do. Once the final invoice is paid, the code, design and accounts are yours.

Can you help after launch?

Yes. I offer hourly support and monthly maintenance for updates, monitoring and new features.

About

Engineer first, partner always.

I'm a full-stack engineer who loves building apps that make people's lives better. I'm a Senior Software Engineer at Starbucks on the integrations team, building custom solutions that help the business run more efficiently. I'm also the founder of Bellynote. Before that I owned features end to end at RentRedi, from the React frontend through backend orchestration.

I hold an M.Eng. in Systems Engineering and a B.S. in Biomedical Engineering from Rensselaer Polytechnic Institute. Outside of work I'm into health and fitness, strong coffee, and reading everything from software design to behavioral psychology.

Senior Software Engineer · StarbucksNov 2026 – Present
Integrations team, building custom solutions that streamline workflows and boost efficiency.
Software Engineer · RentRedi2026
Shipped global Stripe payouts from landlords to tenants and an AI-powered receipt processing system on a rental platform used by hundreds of thousands of people.
Software Engineer · Launchpoint Dev2023 – 2026
Sole engineer on an insurance platform processing $50M+ in annual policy revenue, and built a subscription platform serving 30k+ subscribers.
Junior Software Engineer · Hybrid Performance Method2022 – 2023
Led frontend development for cross-platform mobile apps serving 10k+ users.

Mobile: React NativeExpo
Web: ReactNext.jsTypeScript
Backend: Node.jsStripe
Data: SQLMongoDBSupabase

Contact

Have a project in mind? Let's talk.

Tell me what you're building and where you're stuck. I reply within 1-2 business days with honest next steps, whether or not we end up working together.

Prefer email or socials?