ML Modeling Engineer - Extended Environment - Cortex

New York, NY

Who We Are:

Cortex is the central ML/AI team at Twitter with the goal to build an ML platform and provide deep ML expertise to support our internal customers, while advancing ML inside & outside Twitter.

Our team (ML Extended Environment) is building technologies that enable product teams to create that experience. We are a team of ML engineers and researchers, trying to push boundaries of ML and personalization at Twitter. We work closely with ML product teams across the company (timelines, ads, recommendations, safety etc) to define, design and develop the core components that would enable them to deliver the desired experience to Twitter users.

Example projects include:

- Approximate Nearest Neighbor algorithms and related infrastructure at Twitter scale,

- Embeddings models and algorithms

- Embedding infrastructure that allows teams to easily train, consume and share embeddings.

MLX Blog Post:

Who You Are:

- You have a passion for machine learning.

- You thrive on working in concert with other smart people, including from distributed offices.

- You communicate fluidly, at the level of your audience, and seek to understand and being understood.

- You have the ability to take on complex problems, learn quickly, iterate, and persist towards a good solution.

- You are adamant about studying customer needs and enabling their success through our products.

- You take pride in polishing and supporting our products.

- You welcome feedback on are constantly looking for ways to improve yourself.

What You’ll Do:

You will work with our team of experts in machine learning and software engineering to build powerful and scalable models and surface the most relevant content on Twitter. Come help us make Twitter the best place for finding what the world is saying, live!


- Masters’ or PhD in a Computer Science or Machine Learning related degree; or equivalent work experience in the field

- Good theoretical grounding in core Machine Learning concepts and techniques

- Ability to perform comprehensive literature reviews and provide critical feedback on state-of-the-art solutions and how they may fit to different operating constraints

- Ability to reason about and grasp the intuition behind fundamental principles of Linear Algebra, Statistics, Probability .

- Experience with a number of ML techniques and frameworks, e.g. data discretization, normalization, sampling, linear regression, decision trees, SVMs, deep neural networks, etc

- Familiarity with one or more DL software frameworks such as Tensorflow, PyTorch

- 1+ years experience with one or more DL software frameworks such as Tensorflow, PyTorch, Theano

- 3+ years experience leading and delivering effective ML solutions for large scale production use cases. 


- Experience with large-scale systems and data, e.g. Hadoop, distributed systems

- Familiarity with distributed systems.

- Publications in top conferences such as ICLR, NIPS, ICML, CVPR, ICCV, ECCV, etc

Engineering Hiring Process

Step 1

Once your application is received, a recruiter will reach out pending your qualifications are a match for the role.

Step 2

If your background is a match, you may have 1-2 technical phone interviews or be given the chance to provide a work sample depending on the role.

Step 3

If the phone interviews go well or your work sample is strong, the final step includes interviews with 5-6 people held onsite in our office.


Personal Information

Required field. PDFs only; max file size is 1MB.
Required field. PDFs only; max file size is 1MB.

U.S. Equal Employment Opportunity Information  (Disclosure is voluntary. If you do not wish to disclose, please select "Withold/Decline to Disclose")

At Twitter, we have a bold aspiration to reach every person on the planet. We believe that goal is more attainable with a team that understands and represents different cultures and backgrounds and we are committed to an inclusive and diverse Twitter.

This is where you come in! Please take a few minutes to provide us with your information. You are not required to provide this information and you may select “Decline to Disclose”. Your decision to provide information (or not) will not affect your employment or opportunities at Twitter.

Twitter is an equal opportunity employer. We do not discriminate based on race, color, ethnicity, ancestry, national origin, religion, sex, gender, gender identity, gender expression, sexual orientation, age, disability, veteran status, genetic information, marital status or any legally protected status.

You can view the ‘EEO is the Law’ poster here.

Twitter does not accept any unsolicited resumes from recruiting agencies and will not pay fees associated with any such resumes. Agencies, please do not send resumes to any Twitter location, employee, or email address.

Twitter, Inc. is committed to working with and providing access and reasonable accommodations to applicants with physical or mental disabilities. If you need an accommodation in order to apply for open job opportunities, please submit a description of your accommodation request to This email is only for accommodation requests related to the application process.

Twitter cares about your privacy and protecting your data.  Please click the privacy policy link and acknowledge you have read and understood how Twitter treats your privacy and your data.  

Would you like to receive email communication from Twitter about career opportunities? You may unsubscribe at any time.
Applicant Data - You have a choice. Can we keep your personal data for both the job you are applying for and any other Twitter jobs that we feel you may be a match for? If you choose yes we will retain your personal data for a period of twelve months to consider you for other job opportunities at Twitter.
Analytics - May we use personal data from your resume and application to analyze and improve the Twitter hiring experience.
Thanks for applying!
Submission failed. Please make sure all fields are correctly formatted.

Don't see the right fit?

Check out other opportunities at Twitter.