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

**Company:** [character.ai](https://hotfix.jobs/companies/characterai)
**Location:** Redwood City, CA
**Role:** ML Engineering
**Salary:** $150k – $300k/yr
**Experience:** 8+ years
**Skills:** Python, Go, Java, C++, Machine Learning, Distributed Systems, Content Classification, Anomaly Detection, Feature Engineering, A/B Testing
**Posted:** 2026-01-07

> Designs and builds scalable backend systems and applies machine learning to address safety, integrity, and Generative AI risks. Requires 8+ years backend experience, ML expertise, and distributed systems knowledge.

## Job Description

## What you'll do
- **Architect & Build:** Design, develop, and maintain highly scalable, resilient, and performant backend systems that power our integrity and safety features.
- **Lead Complex Solutions:** Lead the technical design and implementation of sophisticated backend solutions for detecting, preventing, and mitigating integrity risks, including traditional issues and emerging Generative AI threats.
- **Apply Machine Learning:** Conceptualize, develop, deploy, and iterate on machine learning models for content classification, anomaly detection, risk scoring, behavior analysis, and Generative AI safeguards.
- **Cross-Functional Collaboration:** Work with product managers, data scientists, AI researchers, security teams, and operations to define requirements and deliver impactful systems.
- **Technical Strategy & Roadmap:** Drive the long-term technical vision for backend integrity systems and applied ML, aligned with company objectives.
- **Mentorship & Leadership:** Provide technical guidance and mentorship to engineers.
- **Champion Best Practices:** Implement best practices in software engineering, distributed systems, data engineering, and ML lifecycle with focus on Generative AI safety.
- **System Optimization:** Analyze and improve performance, scalability, reliability, and cost-effectiveness of platforms and models.
- **Stay Current:** Keep up with emerging threats, technologies, and advancements in backend engineering, ML for trust & safety, and Generative AI safety.

## Who you are
- 8+ years of professional software engineering experience, with strong emphasis on backend systems development.
- Bachelor's, Master's, or PhD degree in Computer Science, Engineering, or related technical field.
- Proven track record of designing, building, and operating complex, large-scale, highly available distributed systems.
- Expertise in one or more backend programming languages such as Python, Go, Java, or C++.
- Hands-on experience applying machine learning to real-world problems, especially integrity, trust, or safety challenges.
- Solid understanding of the machine learning lifecycle, including data gathering/cleaning, feature engineering, model selection, training, validation, A/B testing, deployment, and monitoring.
- Exceptional problem-solving abilities for ambiguous challenges.
- Proven ability to work in fast-paced environments and deliver timely results.
- Strong communication, interpersonal, and leadership skills.

**You will be a great fit if:**
- You care deeply about Trust & Safety.
- Prior experience in Trust & Safety, Integrity, or Risk engineering team.
- Contributions to open-source projects or publications.
- Experience leading large, cross-cutting technical projects.

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