software engineer

hi, i'm JoshJosh Karasik

i love building things from zero. lately that's meant building an app with 20,000+ active users, training a custom AI model for a global surgical practice, and creating the platforms that keep a Fortune 500's mortgage systems running.

Fortune 500
fintech engineer at PennyMac
20K+
people using apps i've built
100%
uptime on the platforms i run
$1.2M+
client value delivered

a few things i've worked on

PennyMac logo

present

PennyMac

software engineer, developer platforms

i'm a software engineer at PennyMac, a Fortune 500 fintech. i build and run the internal platforms our developers depend on, the systems that keep mortgage payments flowing and our uptime at 100%. i've shipped tools the team uses every day, built telemetry and tracking from the ground up, and i'm now bringing AI into our workflows to make the whole engineering org faster.

AWS · serverless · telemetry · developer tooling · AI

Himplant logo

Himplant

lead developer, iOS & Android

i worked closely with a Beverly Hills plastic surgeon and his team to build something that didn't exist before: a custom, serverless AI model that lets patients see their own results before surgery. it's the only one of its kind. today it has 20,000+ active users, it's on the App Store and Google Play, and dozens of surgeons around the world use it with their patients.

serverless AI · GPU inference · React Native · iOS · Android

RoviSys logo

RoviSys

software engineer

i architected the GUI systems behind Google's AI data center projects, the control interfaces operators rely on every day, and delivered over $1.2M in production value to the client.

GUI systems · industrial automation · architecture

how i got here

i've been around tech my whole life. i just love building things from zero and seeing what becomes possible, how the right tool can help someone get something done faster and change their life a little in the process.

i actually taught myself to code in the back half of college. a friend thought i'd like it, and even though i was a political science major, i fell for it hard. i went deep on the fundamentals, data structures, algorithms, how systems are really built to scale, because i wanted to understand them, not just use them.

when AI showed up it felt like i'd been handed superpowers. the fundamentals i taught myself, plus AI, meant i could build things that used to feel impossible, like the surgical model everyone said couldn't be done. that's the part i love most: taking something that supposedly can't exist and shipping it.

Josh doing stand-up at the Laugh Factory
Josh at a grand piano

outside of work

when i'm not building, i'm usually at a piano. i've played since i was four, and right now i'm working through Pirates of the Caribbean. i'm a little obsessed with good coffee, i make and edit videos (i'm building a channel to teach people about tech), and the book on my desk these days is the Almanack of Naval Ravikant.

the tools i reach for

strong fundamentals first, then whatever ships the product. i care a lot about systems that scale and stay simple.

languages

TypeScript, Python, JavaScript, Swift, SQL

frameworks

React, Next.js, React Native, Node.js

cloud & infra

AWS, Lambda, S3, Terraform, Docker, Kubernetes, CI/CD

data

PostgreSQL, DynamoDB, Redis, GraphQL, REST

ai

LLMs, inference, LoRA fine-tuning, prompt engineering, GPU

foundations

data structures & algorithms, system design, scalable architecture

let's build something good

i'm always up for a good conversation, whether you're hiring, want to build something together, or just have a coffee spot i need to try.

© 2026 Josh Karasik · built from scratch