Character.AI

Software Engineer, Backend/Applied ML (Safety & Integrity)

Character.AI2 months ago
Location

Redwood City, CA

Type

Full Time

Salary

USD 150,000 – 300,000

Level

Senior

Role

Backend Engineer

Posted

Jan 7, 2026

Full TimeSenior

The role

Summary

Character.AI is seeking an experienced Senior Software Engineer specializing in Backend and Applied Machine Learning for Safety & Integrity. The ideal candidate will architect robust backend systems and develop innovative ML solutions to address complex safety challenges in human-to-AI interactions, driving technical leadership in an emerging and critical domain of generative AI technology.

What you'll do

Backend System Architecture: Design, develop, and maintain highly scalable, resilient, and performant backend systems that power integrity and safety features for AI interactions
Machine Learning Solutions: Conceptualize, develop, and deploy machine learning models for content classification, anomaly detection, risk scoring, and generative AI safeguards
Technical Leadership: Drive long-term technical vision for backend integrity systems, providing strategic guidance and mentorship to engineering team members
Cross-Functional Collaboration: Work closely with product managers, data scientists, AI researchers, and security teams to define requirements and develop innovative integrity solutions
System Optimization: Continuously analyze and improve performance, scalability, reliability, and cost-effectiveness of existing integrity platforms and ML models

What we look for

Technical

Backend ProgrammingExpert-level proficiency in backend programming languages such as Python, Go, Java, or C++
Machine LearningComprehensive understanding of ML lifecycle, including data preparation, feature engineering, model development, validation, and deployment
Distributed SystemsProven experience designing and operating complex, large-scale, and highly available distributed systems

Education

Academic BackgroundBachelor's, Master's, or PhD in Computer Science, Engineering, or related technical field

Experience

Professional ExperienceMinimum 8 years of professional software engineering experience, with strong emphasis on backend systems development
Trust & Safety ExperienceDemonstrated experience in addressing integrity, trust, or safety challenges, preferably in dedicated Trust & Safety or Integrity engineering teams

Skills

Required skills

Backend ProgrammingProficiency in Python, Go, Java, or C++
Machine LearningApplied ML techniques for content classification, anomaly detection, and risk assessment
Distributed SystemsDesign and implementation of scalable, high-performance backend architectures

Nice to have

Open Source ContributionsActive participation in open-source projects related to AI, safety, or machine learning
Research PublicationsAcademic publications in fields of AI safety, machine learning, or generative AI

Compensation & benefits

Salary

USD 150,000 – 300,000 (annual)

Benefits

Competitive Compensation

Salary range of $150K-$300K with meaningful equity compensation

Equity Participation

Stock options in a rapidly growing AI unicorn with significant market potential

Hybrid Work Model

Flexible work arrangement with options for remote and in-office collaboration

Professional Development

Opportunities for continuous learning, conference attendance, and cutting-edge AI research involvement

Innovation Environment

Work at the forefront of generative AI technology with a mission-driven, fast-growing startup

Interview process

  1. 1
    Initial Screening — Technical resume review and initial phone screening with recruiting team
  2. 2
    Technical Assessment — Comprehensive coding challenge focusing on backend systems and machine learning problem-solving
  3. 3
    Technical Interviews — Multiple rounds of in-depth technical interviews covering system design, ML techniques, and problem-solving skills
  4. 4
    Leadership and Culture Interview — Assessment of cross-functional collaboration, technical leadership, and alignment with company values
  5. 5
    Final Executive Interview — Discussion with senior technical leadership about long-term vision and potential impact
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Character.AI

Character.AI

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Character.AI is an artificial intelligence company that provides a platform for users to create and interact with customizable AI characters. These characters can simulate conversations with a wide range of personalities, from fictional figures to historical persons and original creations. The company's mission is to make advanced conversational AI accessible and engaging for everyone, fostering creativity and exploration through its innovative technology. It operates within the burgeoning market of AI-driven entertainment and interactive digital experiences, offering a unique blend of user-generated content and sophisticated AI models.

Menlo Park, USAFounded 2022character.ai

Tech Stack

Languages
PythonGoJavaC++
Frameworks
TensorFlowPyTorch
Databases
PostgreSQLMongoDB
Tools
KubernetesDocker
Other
MLOpsAI Safety Frameworks
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