Applied ML Engineer, LLM

About us

Our mission is to become the de facto way people learn foreign languages. We begin by teaching the next billion people English and Spanish.

English is the global language of business, culture, and communication, and over 1.5 billion people around the world are actively trying to learn right now. Others dream of communicating with the half-billion native Spanish speakers across the globe. The problem is that it's nearly impossible to learn to speak a language without constant access to a speaking partner. Grammar and vocab apps don't really help – you need to actually converse with someone.

Speak is on a journey to fix this. We're creating an AI-powered experience that replicates the flow of a conversation, without needing a human on the other end. The goal is to make it radically more accessible to be able to have conversations in a foreign language and eventually help hundreds of millions of people gain fluency who otherwise wouldn't be able to.

We started on this journey over five years ago and we've still got a long ways to go. We're thoughtfully adding new team members only when we think they can truly play a big role in our mission.

Speak launched first in South Korea where we have quickly grown to become the top grossing education app in the country. We have now delivered this winning product to more than 30 countries globally and are continuing to expand to more markets in the coming months. The company is well funded, raising a recent Series B backed by investors like OpenAI, Founders Fund, Y Combinator, Khosla Ventures, Lachy Groom, Josh Buckley, and others. We’re a team of 60 based primarily in SF, Seoul, Tokyo, and Ljubljana.

About this role

As an MLE at Speak, you'll play a pivotal role in developing the future of language learning and creating the most effective path to language fluency. Your primary responsibility will be to spearhead new proofs-of-concept and experiment creatively to help push the boundaries of truly personalized language learning.

Your tasks will span the entire ML lifecycle, from ideation and experimentation to implementation and deployment. You’ll bring the rigor of ML applied research to building out novel LLM product experiences to create new lesson types, to improve assessment/feedback, and to provide a continuously personalized learning experience to users.

We're constantly pushing the boundaries of what LLMs can do to provide an exceptional and unparalleled language learning experience to users in over 30 countries worldwide.

What you'll be doing

  • Collaborating with the Content team to build out a Knowledge Graph to measure and track learner progress over time in Vocab, Grammar, and Pronunciation
  • Building new types of dynamically-generated personalized lessons to teach to each individual learner’s strengths and weakness
  • Working closely with the Product team to enhance our AI-powered lessons and learning features
  • Improving the assessment and monitoring of our prompts via synthetic evaluators

What we're looking for

  • 3+ years experience as a machine learning engineer shipping ML systems into production

    • Proficiency in Python
    • Please apply if you have extensive experience building with LLMs, even if you’re more junior!
  • Experience working with LLMs and strong LLM intuition

    • Experience building and shipping complex LLM systems into production: evaluation, prompt engineering, prompt chaining, finetuning, etc.
    • You’ve probably done several LLM hackathons, built several side projects, tried out many types of models, and use ChatGPT daily.
    • Strong understanding of improving performance & output quality of LLM systems: i.e. prompting vs finetuning, evaluation, model selection, etc.
  • Strong product interest and sense - ability to think broadly/cross-functionally about novel LLM-powered capabilities and product experiences


  • San Francisco, CA

Why work at Speak

  1. Join a fantastic, tight-knit team at the right time: we're growing very quickly, we've raised our Series B and an additional extension from some of the top investors in the valley, and we've achieved product-market fit in our initial markets. You'd join at a magical time when a single person could significantly change the course of the company.
  2. Do your life's work with people you’ll love working with: we care strongly about our craft and want every person at Speak to feel like they're growing every day. We believe in the idea that working with people you both enjoy and have respect for makes everything better. We hire thoughtfully and only work with people we admire deeply.
  3. Global in nature: We're live in over 40 countries and launching in a number of new markets soon. We have dedicated offices in San Francisco, Ljubljana, Seoul, and Tokyo, and you’ll have the opportunity to talk to users in each of these regions on a regular basis as well as travel.
  4. Impact people's lives in a major way: Learning a language is one of the single most life-changing skills one can learn, and right now 99% of people never achieve their goal because the process is broken. We’re helping millions of people achieve their goals and improve their lives.

Speak does not discriminate based upon race, religion, color, national origin, gender (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, or other applicable legally protected characteristics.

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