Machine Learning Engineer Intern (E-Commerce Recommendation Video) - 2027 Start (PhD)

InternHunt; Seattle, Northern (WA, KY); Hybrid; USD 65,000 - 92,000; Full time

Benefits offered by this job

Health insurance

Wellbeing benefits

Paid holidays

Housing allowance

Job summary

TikTok in Seattle is seeking a PhD internship candidate to contribute to our Global E‑Commerce Content Recommendation stack. You will help build and rewrite an industrial recommender serving billions of users, covering retrieval, ranking, and blending end‑to‑end, with production deployment at every iteration.

You will work on LLM‑based retrieval, large‑scale model scaling, and agent‑driven research, gaining hands‑on experience in cutting‑edge systems and bringing ideas from theory to production

Qualifications

• Pursuing a PhD in CS, EE, math, statistics or related discipline.
• Strong ML and engineering fundamentals with clean, reproducible code.
• Experience in LLMs / NLP / CV / RL / or recommendation / search / ads; able to justify choices.
• Genuine enthusiasm for LLM/LRM techniques and production-ready mindset.
• Strong problem definition and decomposition when facing ambiguous problems.

Responsibilities

• Help build and rewrite an industrial recommender for a billion-scale user base.
• Work on retrieval, ranking, and blending end-to-end with production deployments.
• Contribute to scalable model development, training and inference acceleration.

Skills

ML fundamentals

Algorithms & data structures

Clean code

Research mindset

Education

PhD in Computer Science, Electrical Engineering, Math, Statistics or related

Tools

CUDA / Triton kernels

DL frameworks

Job description

Seattle, WA

2026-10-08

Role Description

ResponsibilitiesGlobal E-Commerce (TikTok Shop) is one of TikTok's fastest-growing businesses and a core driver of the company's revenue growth. Our Global E-Commerce Content Recommendation team owns the end-to-end recommendation stack for e-commerce video and image-text content on TikTok worldwide — retrieval, ranking, and multi-queue blending; supply ecosystem and cold start; and the browsing-to-purchase experience for hundreds of millions of users.

We believe recommendation is being rewritten in the compute era. ID-based collaborative filtering and supervised learning built today's systems and still run most of the industry — but their returns are diminishing, and we are betting the next order of magnitude on rebuilding the stack on LLM foundations. Our ambition is to build the most advanced recommendation system in the world, and the next generation after that.

We are looking for talented individuals to join us for an internship. PhD internships at Our Company provide students with the opportunity to actively contribute to our products and research, as well as to the organization's future plans and emerging technologies.

Our dynamic internship experience blends hands‑on learning, enriching community‑building and professional development events, and collaboration with industry experts.

Responsibilities:You will help build — and rewrite — an industrial recommendation system serving a billion‑scale user base across short‑video, livestream, and product scenarios, covering retrieval, pre‑ranking, ranking, and blending end to end. Every iteration ships to production and directly moves user experience and GMV.

• Scale recommendation models like LLMs. Push ranking models from hundreds of millions to billions of parameters and chart the scaling laws of recommendation: behavior‑corpus pretraining; multi‑scenario, multi‑task, multi‑stage joint training; ultra‑long behavior‑sequence modeling (10K+ events) with KV caching, sequence compression, user/generation (U‑G) disaggregated serving, speculative decoding, and dynamic batching — raising MFU while holding a strict millisecond latency budget.
• Build one‑stage generative retrieval. Reframe retrieval as generation: tokenize the item space into semantic IDs (RQ‑VAE / SID) and train autoregressive models, grounded in MLLM semantics, to generate what a user wants next — collapsing the traditional “multi‑channel retrieval + ranking” funnel into a single generative stage. The open problems span the full stack: item tokenizers that balance semantic content against collaborative signal, and SIDs that stay stable while millions of new items arrive daily; post‑training the generator directly on live user feedback (preference optimization, GRPO‑style RL); and decoding under a millisecond budget — beam search, decoding constrained to the valid item space, and test‑time scaling that trades inference compute for better recommendations. The prize is a system freed from its path dependence on ID memorization, where cold‑start generalization comes from semantics rather than impression history.
• Inject world knowledge. Use large models' real‑world knowledge to mine latent user interests and semantic representations beyond what pure ID co‑occurrence can express; use reasoning models to run explicit chain‑of‑thought inference over long‑horizon user intent, making the system materially better at discovery and novelty.
• Push training and inference to the hardware limit. Custom CUDA / Triton fused kernels, memory and computation‑graph optimization, distributed training and inference acceleration, mixed precision and low‑bit quantization — engineered for what makes recommendation hard: sparse embeddings, variable‑length sequences, and many task heads.
• Rewrite R&D with agents. We are embedding coding agents deep into the algorithm‑development loop: automated feature mining and pipeline generation, experiment configuration and training orchestration, automated evaluation and online‑diagnosis attribution, bad‑case mining and patrol. You will be both a user and a builder of this system.
• Do original work on open problems. Long‑term value modeling, repurchase and retention, transaction attribution, fatigue modeling, new‑user recommendation, incremental value modeling, interest exploration, LLM4Rec — problems where industry has no standard answers. We expect, and support, original research: internal papers, patents, and publication at top external venues.

QualificationsMinimum Qualifications:

• Currently pursuing a PhD in Computer Science, Electrical Engineering, Mathematics, Statistics or a related discipline.
• Solid ML and engineering fundamentals: you understand the math behind the models, and you write clean, efficient, reproducible code with a strong command of algorithms and data structures.
• Deep research or engineering practice in at least one of: LLMs / foundation models, NLP, CV, RL, or recommendation / search / ads — and you can articulate why you made the choices you made, and where they fell short.
• Genuine enthusiasm for LLM / LRM techniques: you want frontier methods live in production, not parked at offline metrics.
• Strong problem definition and decomposition: faced with an ambiguous problem that has no standard answer, you find your own foothold.

Preferred Qualifications:

• Publications at KDD, SIGIR, RecSys, WWW, ACL, NeurIPS, ICML, ICLR, or comparable venues — or high‑quality open‑source work.
• CUDA / Triton kernel development, source‑level deep‑learning‑framework optimization, large‑scale distributed training, or high‑performance inference deployment.
• Hands‑on experience with LLM post‑training (SFT / RLHF / DPO / GRPO), agent‑system construction, or inference acceleration.
• Led or deeply contributed to a key project in search, ads, recommendation, or large models, with a complete problem‑to‑online‑impact loop.
• Awards in ACM‑ICPC, NOI, Kaggle, or comparable competitions.
• Heavy user of AI coding and agentic workflows for building systems and optimizing models.

Job Information

The hourly rate range for this position in the selected city is $57- $57.

Benefits may vary depending on the nature of employment and the country work location. Interns have day one access to health insurance, life insurance, wellbeing benefits and more. Interns also receive 10 paid holidays per year and paid sick time (56 hours if hired in first half of year, 40 if hired in second half of year). Interns who are not working 100% remote may also be eligible for housing allowance.

The Company reserves the right to modify or change these benefits programs at any time, with or without notice.

For Los Angeles County (unincorporated) Candidates:Qualified applicants with arrest or conviction records will be considered for employment in accordance with all federal, state, and local laws including the Los Angeles County Fair Chance Ordinance for Employers and the California Fair Chance Act. Our company believes that criminal history may have a direct, adverse and negative relationship on the following job duties, potentially resulting in the withdrawal of the conditional offer of employment:

• Interacting and occasionally having unsupervised contact with internal/external clients and/or colleagues;
• Appropriately handling and managing confidential information including proprietary and trade secret information and access to information technology systems; and
• Exercising sound judgment.

About TikTokTikTok is the leading destination for short‑form mobile video. At TikTok, our mission is to inspire creativity and bring joy. TikTok's global headquarters are in Los Angeles and Singapore, and we also have offices in New York City, London, Dublin, Paris, Berlin, Dubai, Jakarta, Seoul, and Tokyo.

Why Join Us

Inspiring creativity is at the core of TikTok's mission. Our innovative product is built to help people authentically express themselves, discover and connect – and our global, diverse teams make that possible. Together, we create value for our communities, inspire creativity and bring joy - a mission we work towards every day.

We strive to do great things with great people. We lead with curiosity, humility, and a desire to make impact in a rapidly growing tech company. Every challenge is an opportunity to learn and innovate as one team. We're resilient and embrace challenges as they come. By constantly iterating and fostering an "Always Day 1" mindset, we achieve meaningful breakthroughs for ourselves, our company, and our users. When we create and grow together, the possibilities are limitless. Join us.

Diversity & Inclusion

TikTok is committed to creating an inclusive space where employees are valued for their skills, experiences, and unique perspectives. Our platform connects people from across the globe and so does our workplace. At TikTok, our mission is to inspire creativity and bring joy. To achieve that goal, we are committed to celebrating our diverse voices and to creating an environment that reflects the many communities we reach. We are passionate about this and hope you are too.

TikTok Accommodation

TikTok is committed to providing reasonable accommodations in our recruitment processes for candidates with disabilities, pregnancy, sincerely held religious beliefs or other reasons protected by applicable laws. If you need assistance or a reasonable accommodation, please reach out to us at https://tinyurl.com/RA-request