---
title: 'Software Engineer, Backend/Applied ML (Safety & Integrity) at Character.AI'
canonical: 'https://feeny.ai/job/software-engineer-backend-applied-ml-safety-integrity-character-ai-redwood-city-4q5mdjeptsz5'
type: 'job'
last_seen: '2026-09-10'
---

# Software Engineer, Backend/Applied ML (Safety & Integrity) at Character.AI

- **Company:** Character.AI
- **Location:** Redwood City, CA
- **Compensation:** $150k–$300k
- **Employment:** full-time
- **Work type:** hybrid
- **Posted:** 2026-01-07
- **Last confirmed live:** 2026-09-10
- **Apply:** https://jobs.ashbyhq.com/character/690f5ec2-2d7b-4c28-9b4d-d710e7225851/application

**Skills:** Python, Go, Java, C++, Machine Learning, Distributed Systems, Backend Development, Data Engineering, Model Training and Validation, A/B Testing, Operational Monitoring, Open Source Contribution, Trust & Safety Engineering, Integrity Engineering, Risk Engineering

> Design, develop, and scale robust backend systems and apply machine learning to tackle integrity and safety challenges in human-to-AI interaction. The role involves architecting solutions for content classification, anomaly detection, and Generative AI mitigation while providing technical leadership and mentorship.

## Job description

## About the role

We’re looking for a talented and creative Software Engineer to join our Safety Engineering team at [Character.AI](http://Character.AI)! In this role, you will be at the forefront of designing, developing, and scaling robust backend systems and leveraging applied machine learning to tackle critical integrity and safety challenges. You will be architecting and implementing innovative solutions in a key role in addressing the unique safety challenges that come with human-to-AI interaction—bringing your technical expertise to the table as we define industry best practices in this emerging space. This is a high-impact role where you will provide technical leadership, drive innovation, and contribute to the core of our platform's trustworthiness.

## 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 a wide array of integrity risks. This includes traditional issues (e.g., content classification, spam, etc.) as well as emerging threats related to Generative AI (e.g., misuse of generative models, generation of harmful or biased content, etc).
- Apply Machine Learning: Conceptualize, develop, deploy, and iterate on machine learning models and algorithms to address complex integrity challenges. This includes areas like content classification (including AI-generated content), anomaly detection, risk scoring, behavior analysis, and developing safeguards for Generative AI systems (e.g., robust content filtering, bias mitigation techniques, and output monitoring).
- Cross-Functional Collaboration: Work closely with product managers, data scientists, AI researchers, security teams, and operations to define requirements, design innovative solutions, and deliver impactful integrity systems, especially for Generative AI products.
- Technical Strategy & Roadmap: Drive the long-term technical vision and roadmap for backend integrity systems and applied ML capabilities, with a keen eye on addressing Generative AI safety concerns with an alignment with company objectives.
- Mentorship & Leadership: Provide technical guidance and mentorship to other engineers on the team and across the organization, fostering a culture of engineering excellence.
- Champion Best Practices: Advocate for and implement best practices in software engineering, distributed systems design, data engineering, and the full lifecycle of ML model development, including specific considerations for the safety and ethics of Generative AI.
- System Optimization: Continuously analyze and improve the performance, scalability, reliability, and cost-effectiveness of existing integrity platforms and ML models.
- Stay Current: Keep abreast of emerging threats, new technologies, and advancements in backend engineering, distributed systems, the application of machine learning to trust and safety, and the evolving landscape of Generative AI safety research and mitigation techniques.

## Who you are

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

You will be a great fit if:

- You care deeply about Trust & Safety and see it as a value-add to the business
- Prior experience in a dedicated Trust & Safety, Integrity, or Risk engineering team.
- Contributions to open-source projects or publications in relevant fields.
- Experience leading large, cross-cutting technical projects.

## About Character.AI

[Character.AI](http://Character.AI) empowers people to connect, learn and tell stories through interactive entertainment. Over 20 million people visit [Character.AI](http://Character.AI) every month, using our technology to supercharge their creativity and imagination. Our platform lets users engage with tens of millions of characters, enjoy unlimited conversations, and embark on infinite adventures.

In just two years, we achieved unicorn status and were honored as Google Play's AI App of the Year—a testament to our innovative technology and visionary approach.

Join us and be a part of establishing this new entertainment paradigm while shaping the future of Consumer AI!

At Character, we value diversity and welcome applicants from all backgrounds. As an equal opportunity employer, we firmly uphold a non-discrimination policy based on race, religion, national origin, gender, sexual orientation, age, veteran status, or disability. Your unique perspectives are vital to our success.

## About Character.AI

## Company Overview
- **One-liner**: Character.AI builds a full-stack, direct-to-consumer platform where users interact with AI-powered "Characters" for open-ended conversation, storytelling, and entertainment.
- **Entity Type**: Private (Venture Capital-Backed)
- **Headquarters**: Menlo Park, California, United States
- **Founded**: 2021
- **Founders**: Noam Shazeer and Daniel De Freitas

## Core Business
- **Primary industry/industries**: Entertainment Software, Artificial Intelligence & Machine Learning, SaaS (B2C)
- **Target customers**: B2C — millions of monthly active users seeking virtual companions, creative storytelling, and interactive entertainment.
- **Mission or purpose statement**: "Empower people to connect, learn, and tell stories through interactive entertainment."

## Products & Services
- **Character.AI Platform**: A web and mobile application that allows users to create, discover, and converse with AI Characters. The platform supports user-generated content, enabling users to build heroes, settings, stories, and challenges. It sits at the intersection of storytelling, gaming, social connection, and creative expression.

## Market Standing
- **Valuation/Market Cap**: Not publicly disclosed (latest known round: Secondary Transaction - Private, completed at "Generating Revenue" stage per PitchBook).
- **Key Metric**: Total Funding raised — **$193M** (Series A: $43.1M in 2022; Series A extension/round: $150M in March 2023).
- **Notable Investors/Partners**: Andreessen Horowitz, Google, Greycroft, SV Angel, Elad Gil, and 8 total investors. [cbinsights.com](https://www.cbinsights.com/company/characterai)
- **Growth Signals**: 
    - Millions of monthly active users.
    - Headcount of ~130 employees as of 2026.
    - Offices in Silicon Valley (HQ), Seattle, and New York.
    - The company completed a "Reverse Acqui-Hire" transaction, signaling strong talent acquisition interest from larger players.

## Competitive Advantages
- **Deep Technical Talent**: Founded by AI pioneers Noam Shazeer and Daniel De Freitas, who bring deep expertise in machine learning and natural language processing.
- **Full-Stack AI Platform**: Unlike many chatbot APIs, Character.AI owns the entire stack from model inference to consumer interface, giving them control over user experience and data.
- **Strong User Engagement & Community**: The platform has built a passionate community of creators and users who generate and share content, creating a network effect moat.
- **Brand Recognition**: One of the leading independent consumer AI platforms globally, with a clear identity as an entertainment-first product.

## Strategic Focus
- **AI-driven Entertainment**: The company is focused on redefining entertainment through generative AI, moving beyond simple chatbots into immersive, interactive experiences.
- **User-Generated Content (UGC)**: Empowering users to create their own characters and worlds is a core strategic priority, differentiating them from single-purpose AI tools.
- **Monetization & Scale**: Moving from a free product toward a sustainable business model (subscription tiers like c.ai+) while scaling the platform to serve a global user base.
- **Talent Acquisition**: Actively hiring across ML research, engineering, and safety to build out the next generation of their product.

## Why Work Here
- **Mission-Driven Work**: Opportunity to work on cutting-edge generative AI and shape the future of entertainment for millions of users.
- **High-Impact Environment**: Described as a "small, passionate team" where individuals can have significant ownership and influence.
- **Strong Compensation**: Competitive salaries (e.g., Research Engineer, AI Safety & Alignment: $225K–$400K + equity). [jobs.ashbyhq.com](https://jobs.ashbyhq.com/character/)
- **Comprehensive Benefits**:
    - **Parental Leave**: 20 weeks paid for birthing parents, 12 weeks for non-birthing parents.
    - **Retirement**: 401(k) match up to $5,875/year (25% of contributions up to IRS cap).
    - **Time Off**: 20 days accrued PTO, 12 company-paid holidays, plus accrued sick time.
    - **Health**: 100% premium coverage for medical (PPO or HSA), dental, and vision for employees; 80% for dependents. Life, AD&D, and LTD insurance fully covered.
    - **Perks**: Daily lunch in all offices, monthly DoorDash credit, monthly commuter allowance ($50), and a quarterly wellness stipend.
- **Work Policy**: Hybrid (offices in Menlo Park, Seattle, New York).
- **Culture Values**: "Users First" (users > company > team), "Think Transformational," and a focus on collaboration and high performance.

## Sources
1. [character.ai/about](https://character.ai/about)
2. [character.ai/careers](https://character.ai/careers)
3. [jobs.ashbyhq.com/character/](https://jobs.ashbyhq.com/character/)
4. [cbinsights.com](https://www.cbinsights.com/company/characterai)
5. [pitchbook.com](https://pitchbook.com/profiles/company/512290-54)

## Other roles at Character.AI

- [Technical Program Manager, Product Experience](https://feeny.ai/job/technical-program-manager-product-experience-character-ai-redwood-city-m9zmhkmgt1qy) — Redwood City, CA
- [Principal Research Engineer, Post-Training](https://feeny.ai/job/principal-research-engineer-post-training-character-ai-redwood-city-92f6f7sk06h1) — Redwood City, CA
- [Technical Program Manager, Model Alignment and Deployment](https://feeny.ai/job/technical-program-manager-model-alignment-and-deployment-character-ai-redwood-brmkpc2gvra0) — Redwood City, CA
- [Staff Data Scientist, Monetization](https://feeny.ai/job/staff-data-scientist-monetization-character-ai-redwood-city-51hmwhgh6e2k) — Redwood City, CA
- [Technical Program Manager, AI Infrastructure](https://feeny.ai/job/technical-program-manager-ai-infrastructure-character-ai-redwood-city-3ty4trwmewr9) — Redwood City, CA
- [Software Engineer, Applied ML (Discovery, Recommendation & Search)](https://feeny.ai/job/software-engineer-applied-ml-discovery-recommendation-search-character-ai-5r4a2m0v7fzq) — Redwood City, CA
- [Software Engineer, Backend](https://feeny.ai/job/software-engineer-backend-character-ai-redwood-city-kx5x7rxznvz7) — Redwood City, CA
- [Software Engineer, Monetization](https://feeny.ai/job/software-engineer-monetization-character-ai-redwood-city-4wjqzcp5e490) — Redwood City, CA
- [Software Engineer, Core Product](https://feeny.ai/job/software-engineer-core-product-character-ai-redwood-city-h676pc9pz8k1) — Redwood City, CA
- [Research Engineer, AI Safety & Alignment](https://feeny.ai/job/research-engineer-ai-safety-alignment-character-ai-redwood-city-p2gtwtpvekg7) — Redwood City, CA