Justin Garcia

Product engineer at Kotoba
onemorething.tokyo | Email | GitHub | LinkedIn
I ship real-time speech AI products at Kotoba. I previously worked for 9 years at Apple on Siri’s initial release, iOS text input and WebKit’s editing engine.

Experience

Kotoba (Aug 2025 – Present)Tokyo
Senior Software Engineer
I build the apps and integrations that put Kotoba’s speech translation models in front of customers.
  • Shipped Kotoba’s on-device Japanese TTS for the Meta Ray-Bans with a 5-person team, working directly with Meta’s engineers. Improved inference speed and memory footprint
  • Helped build subscriptions into Kotoba’s low-latency speech translation app. It reached $400K ARR in 5 months
  • Implemented v1 of the live-translation bots for Zoom, Google Meet and Teams. They are part of the product now used by ~15 enterprise customers
  • Built the pipeline that automatically evaluates new speech-to-speech translation models using the research team’s scoring system and MOS for voice quality
  • Created Sendai, a Slack agent that turns English and Japanese release requests into App Store Connect actions to manage iOS releases
Career break (Apr 2024 – Aug 2025)Tokyo
I relocated to Japan, studied Japanese, learned Rails, and built most of the backend for a YouTube summarizer, which I demoed at Google’s Tokyo campus.
Procore (Jul 2018 – Mar 2024)California
Senior iOS Software Engineer
I worked on Procore for iOS, the mobile app for a leading global construction management platform.
  • Designed and built the iOS system that lets enterprise clients like Amazon add their own custom fields
  • Fixed 50+ high-volume crashes impacting customers
  • Cut 30s from every iOS build (~20%) across a 20-engineer team by extracting stable code into a prebuilt binary
iHeartMedia (Dec 2016 – Oct 2017)New York City
iOS Software Engineer
I worked on iHeartRadio for iOS, iHeartMedia’s music, podcast and live radio app (100M+ registered users), and shipped its redesigned podcast browsing and playback.
Career break (Jul 2014 – Nov 2016)San Francisco and Florida
I worked for Musey, an early-stage San Francisco startup, where I helped ship a couple of iPhone apps. I also moved back to my hometown to be with my father, who passed away in 2015.
Apple (Jun 2005 – Jun 2014)Cupertino
Software Engineer
I worked on Safari/WebKit first and then moved to iOS keyboard and text input in 2009.
  • Led development on keyboard dictation for Siri’s initial release
  • Made Cut / Copy / Paste fast enough on the original iPhone to ship in iPhone OS 3
  • Owned WebKit’s WYSIWYG editing engine (which powers Mail) for 3 years
  • Presented at WWDC in 2011 and 2012 on the iOS text input system
  • Built most of the Siri streaming animation that was new in iOS 8

Independent apps

I design, build and ship my own free products.
Karui: notification filtering with Apple’s on-device model, Private Cloud Compute or a frontier cloud model

Education

Rice University (2005), B.A. in Computer Science

Patents

Mapping application search function (Apple, for CarPlay)