Paul Tarjan

Distinguished Software Engineer

Calgary, Alberta, Canada

About

For nice clickable links about these things see my resume: http://paultarjan.com/resume.html

Experience

  • Member of Technical Staff at Anthropic
    Dec 2025 - Present · 7 mos

  • Distinguished Software Engineer at Robinhood
    Feb 2020 - Oct 2022 · 2 yrs 9 mos

    * Hired as the senior-most IC at the company to level up engineering * Built the Change Management program getting all services onto hermetic builds, canaries, automated rollbacks, and containers. Cut our self-inflicted incident rate by 1/2. * Represented Robinhood for Ernst & Young FINRA, SOX, and ICOC audits * Wrote the technical standards documents for what software and languages we use in engineering * Moved to a monorepo. Removing git-lfs, submodules, and deployment version drift. * Migrated the company to bazel * Improved test pass rate from abysmally low to 99% * Built out the senior staff+ IC engineer group from 2 to 50. Created the interview loop for Sr. Staff+, trained others on it, ran the meetings amongst the senior-most engineers, etc. * Founded the Developer Infra org and grew it to 60 people * Insists on staying close to the code as the 9th highest code contributor, period. More than double the next highest Senior Staff+ engineer.

  • Principal Software Engineer at Stripe
    Jan 2016 - Jan 2020 · 4 yrs 1 mo

    * Founded Developer Productivity team to be responsible for Engineer velocity. Grew team from 4 of the most senior engineers to 50 across 3 offices and 2 layers of managers. * Coached Engineering Advisors and Engineering Review teams for company-wide senior engineering decisions. * Authored Stripe's Technical Architecture internal documentation about how we build our software. * Highest code contributor at Stripe. * Envisioned, staffed, and built Sorbet, a typechecker for Ruby.

  • Founder and CTO at Trimian
    Apr 2015 - Dec 2015 · 9 mos

    * Built the initial prototype, setup the development toolchain, infrastructure, release process, style guides, company culture, etc. Continued to be the largest code contributor. * Raised seed funding from prominent angels and VC firms. * Grew the team to ten members across two offices.

  • Senior Staff Software Engineer at Facebook
    Mar 2010 - Apr 2015 · 5 yrs 2 mos

    * #14 engineer by commits. #5 by reviews. Top 40 Tech Leadership. Engineer ~#200. * Created and led the Web Speed team. 30% improvement in E2E in 6 months for facebook.com. * Led the HHVM Open Source team. Worked with Wikipedia, Box, and Etsy to switch compilers. * Wrote many Product Infrastructure abstractions: ** Designed the DynamicYield abstraction to help migration from preparables to generator-based data fetching ** Wrote the GenXHP UI layer which forces efficient inline data fetching instead of overfetching ** Deleted the module system (3 million lines of code) and replaced it with an autoloader * Led Dublin Bootcamp * Founded the Open Graph Protocol 2.0 team to verb any noun on Facebook * Extended OAuth2 to have Signed Requests * Created the URL Debugger * Founded the College Hackathon program and MCed over 50 hackathons worldwide * Wrote the Registration Plugin