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  1. Meet a Duo: André Kenji Horie, Senior Software Engineer

    Meet André Kenji Horie, a Senior Software Engineer who has been at Duolingo for three years. André came all the way from Brazil to Pittsburgh, with a few years in Tokyo in between. We asked André about where he's from, what it's like to work at Duolingo and what he thinks about living in Pittsburgh.

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  2. Rewriting Duolingo's engine in Scala

    Recently, we profoundly refactored the engine that drives Duolingo lessons. This post talks about our engineering choices, experiences, and the pain points of rewriting a highly complex system.


    • Redesigned architecture
    • Refactored code from Python to Scala
    • Latency dropped from 750ms to 14ms
    • Engine uptime increased from 99.9% to …

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