Machine Learning Engineer - Ads Retrieval

reddit; London; On-site; GBP 70,000 - 90,000; Full time

Job summary

A leading social media company in London is hiring a Machine Learning Engineer for their Ads Retrieval team. The role focuses on building machine learning models for candidate sourcing and optimizing ad delivery. Candidates should have 5+ years of experience in applied ML, proficiency in programming languages, and knowledge in data pipeline orchestration. Benefits include a pension scheme and flexible vacation policies.

Benefits

Pension Scheme

Private Medical and Dental Scheme

Life Assurance

Income Protection

Workspace benefit for home office

Professional development funds

Family Planning Support

Commuter Benefits

Flexible Vacation

Global Days Off

Qualifications

• 5+ years of experience with applied machine learning models.
• 5+ years of end-to-end experience of training and deploying models.
• Proficiency in programming languages (Java, Python, Golang, C++).
• Experience with orchestrating data pipelines.

Responsibilities

• Build ads retrieval and early ranking systems.
• Research, implement, and launch model architectures.
• Work on large-scale data systems and backend services.
• Collaborate with product, engineering, and marketing teams.

Skills

Applied machine learning models (TensorFlow/PyTorch)

End-to-end machine learning experience

Programming languages (Java, Python, Golang, C++)

Statistical analysis

Data pipeline orchestration

Information retrieval

Recommendation systems

Job description

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Machine Learning Engineer - Ads Retrieval, London

Client: reddit

Location: London, United Kingdom

Job Category: Other

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EU work permit required: Yes

Job Reference: 1f8df558ea1d

Job Views: 19

Posted: 12.08.2025

Expiry Date: 26.09.2025

Job Description:

Reddit is a community of communities. It’s built on shared interests, passion, and trust and is home to the most open and authentic conversations on the internet. Every day, Reddit users submit, vote, and comment on the topics they care most about. With ,+ active communities and approximately M+ daily active unique visitors, Reddit is one of the internet’s largest sources of information. For more information, visit .

The Ads Retrieval team’s mission is to identify business opportunities, provide ML models and data-driven solutions on candidate sourcing, recommendation, early ranking, and filtering in Ads upper funnel. The team works on:

• Build and iterate on candidate sourcing and early ranking Machine Learning models and algorithms to find the most relevant, engaging, and diversified ads candidates for global optimization and various product use cases.
• Design and establish a large-scale candidate indexing system to enable efficient candidate retrieval at a scale of millions to billions, which powers ads recommendation and ranking with a good balance between quality and computation efficiency.

As a machine learning engineer in the ads retrieval team, you will research, formulate, and execute on our mission to build end-to-end ML solutions and deliver the right ad to the right user under the right context with data and ML-driven solutions.

Your Responsibilities:

• Build ads retrieval and early ranking systems for critical ML tasks with advanced industrial-level techniques.
• Research, implement, test, and launch new model architectures including information retrieval, ANN, recommendation systems, deep neural networks within high-dimensional information systems.
• Work on large-scale data systems, backend services, and product integration.
• Collaborate closely with multiple stakeholders across product, engineering, research, and marketing.

Who You Might Be:

• + years of experience with applied machine learning models with TensorFlow/PyTorch with large-scale ML systems.
• + years of end-to-end experience of training, evaluating, testing, and deploying machine learning models.
• Proficiency with programming languages (Java, Python, Golang, C++, or similar) and statistical analysis.
• Experience in orchestrating complicated data pipelines and system engineering on large-scale datasets.
• Prior experience with information retrieval and recommendation systems.
• Ads domain knowledge on product and ML solutions is a plus.

Benefits:

• Pension Scheme
• Private Medical and Dental Scheme
• Life Assurance, Income Protection
• Workspace benefit for your home office
• Personal & Professional development funds
• Family Planning Support
• Commuter Benefits
• Flexible Vacation & Reddit Global Days Off

Join us at Reddit, and help us build a community that is inclusive and empowering for everyone.