{"id":69732,"url":"https://alion.io/job/inflection-principal-research-engineer-model-training-post-training","title":"Principal Research Engineer, Model Training & Post-Training","company":{"id":31705,"name":"Inflection AI","domain":"inflection.ai","url":"https://alion.io/company/inflection-ai","size_band":"51-200","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Greenhouse","truth_index":{"grade":"B","score":75,"open_postings":4,"ghost_share":0,"stale_share":1,"repost_share":0,"time_to_fill_p50_days":null,"computed_at":"2026-10-17T05:46:00Z"}},"role":"AI/ML","role_family":"AI/ML","seniority":"lead","employment_type":null,"work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["Palo Alto, United States"],"countries":["US"],"hiring_countries":[],"hiring_countries_total":0,"salary":{"min":400000,"max":550000,"currency":"USD","period":"year","gross":null,"usd_annual":550000},"salary_estimate":null,"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":true,"technologies":[{"name":"AI Agents","optional":false},{"name":"DPO","optional":false},{"name":"Fine-tuning","optional":false},{"name":"Function Calling","optional":false},{"name":"GRPO","optional":false},{"name":"Human-in-the-Loop","optional":false},{"name":"Knowledge Distillation","optional":false},{"name":"LLM","optional":false},{"name":"Machine Learning","optional":false},{"name":"Model Distillation","optional":false},{"name":"Multimodal AI","optional":false},{"name":"Post-training","optional":false},{"name":"Reward Modeling","optional":false},{"name":"RLAIF","optional":false},{"name":"RLHF","optional":false},{"name":"SFT","optional":false},{"name":"Synthetic Data","optional":false},{"name":"Tool Use","optional":false}],"status":"live","first_seen_at":"2026-06-29T19:59:46Z","employer_posted_date":"2026-08-06","last_verified_at":"2026-10-17T16:18:06Z","board_verified":true,"closed_at":null,"days_open":109,"trust":{"level":"stale","repost_count":0,"flags":["stale"],"days_open":109},"description":"About Inflection AI\nInflection AI is a Public Benefit Corporation empowering people with human-centered, emotionally intelligent AI. We’re shaping the future of AI by combining emotional intelligence (EQ) and raw intelligence (IQ) to elevate people’s potential.\nInflection AI created Pi, the world’s first emotionally intelligent AI, to help people work through decisions, emotions, and challenges. Pi is a personal AI agent powered by Inflection AI’s foundation model, proving that AI can be personal, empathetic, and contextually aware.\nAbout the Role\nInflection’s models are central to our product and platform strategy, and we are looking for a hands-on technical leader to own the model-improvement loop from data and training through evals, post-training, release criteria, and production feedback. This person will sit at the intersection of research, production engineering, and model release, with a mandate to ship models that are measurably better for users. The ideal candidate has led serious model training or post-training work before, can make principled tradeoffs across data, compute, architecture, and quality, around a clear technical roadmap.\nWhat You’ll Do\nOwn the model-improvement roadmap across capability, reliability, emotional intelligence, tool use, safety, latency, cost, and enterprise readiness.\nLead training and post-training strategy, including supervised fine-tuning, RLHF, DPO, GRPO, RLAIF, reward modeling, preference optimization, tool-use fine-tuning, distillation, synthetic data, and related methods.\nDrive model architecture and optimization decisions across modern transformer-based and hybrid architectures, including both training-time and inference-time performance.\nLead large-scale training efforts on distributed GPU clusters, including systems operating at the scale of 1,000+ GPUs.\nDefine and execute data strategy across data curation, mixture design, deduplication, decontamination, human-in-the-loop pipelines, preference data, evaluation data, synthetic data, and production feedback loops.\nBuild and improve evaluation and release-quality systems, including model evals, quality gates, regression detection, release criteria, model-readiness reviews, and post-release monitoring.\nPartner closely with infrastructure and research engineering teams to improve distributed training reliability, checkpointing, fault tolerance, observability, reproducibility, and cost-performance tradeoffs.\nDebug and improve model behavior across the full stack: data, training, post-training, evaluation, infrastructure, product integration, and production feedback.\n\nWhat We’re Looking For\nExperience leading, or serving as a principal contributor to, large-scale LLM, multimodal, or foundation-model training or post-training programs.\nDeep experience with transformer-based models, hybrid architectures, modern deep-learning frameworks, and distributed training systems.\nStrong practical experience with post-training and alignment methods such as SFT, RLHF, DPO, GRPO, RLAIF, reward modeling, preference optimization, tool-use fine-tuning, or related approaches.\nExperience operating or partnering on large-scale training infrastructure, ideally including GPU clusters at the scale of 1,000+ GPUs.\nStrong systems instincts around throughput, cost, reliability, observability, debugging, checkpointing, reproducibility, and fault tolerance.\nExcellent judgment around data quality, evaluation design, model regressions, release readiness, and production model behavior.\nAbility to balance research ambition with product pragmatism, user impact, and operational discipline.\nExperience leading senior technical teams while continuing to contribute directly to technical decisions and implementation.\nPhD in Computer Science, Machine Learning, Artificial Intelligence, or a related field, or equivalent practical experience.\nEmployee Pay Disclosures\nAt Inflection AI, we aim to attract and retain the best employees and compensate them in a way that appropriately and fairly values their individual contributions to the company. For this role, Inflection AI estimates a starting annual base salary to fall within the range of $400,000 to $550,000, depending on a candidate’s qualifications and level of experience. This role also includes a meaningful equity component, allowing employees to share in the long-term success of the company.\nBenefits\nInflection AI values and supports our team’s mental, emotional, financial and physical health. We are focused on building a positive, safe, inclusive and inspiring place to work. Our benefits include: \nRobust medical, dental and vision options with employer contributions for HSA, FSA and DFSA\n401k matching program \nFlexible Time Off, 10 paid holidays, 5 days sick leave\nParental, Medical and Family care leave \nGenerous cell-phone, wellness and office set up stipends \nSupport of country-specific visa needs for international employees living in the Bay Area","description_format":"text","description_chars":4946,"description_truncated":false,"requirements":{"experience_years_min":null,"management_years_min":null,"team_size_min":null,"manages_managers":false,"education":{"level":"phd","optional":false},"security_clearance":false,"languages":[]},"benefits":["401k plan","Equity","Flexible time off"],"hiring_locations":[],"hiring_excludes":[],"relocation_offered":false,"industries":["LLM & Generative AI","Conversational AI"],"lifecycle":[{"event":"open","at":"2026-06-29T19:59:46Z"}],"visa":[{"country":"US","licensed_sponsor":true,"evidence":"H-1B filings in 12 months: 4","filings_12m":4,"filings_prev_12m":2,"green_card_filings_12m":0,"median_offered_wage_usd":247500,"route":null,"cap_exempt":false,"checked_at":"2026-10-15T11:24:14+00:00","sources":["US Department of Labor: LCA disclosure data (H-1B, H-1B1, E-3)"],"filings_for_role_12m":4}],"liveness":{"score":10,"band":"cold","label":"Long shot","p_open":1,"p_active":0.347,"p_room":0.28,"age_days":109,"expected_fill_days":30,"reasons":["conf:2","win:tail","crowd:"],"computed_at":"2026-10-17T05:46:00Z"},"pay":{"stated_usd_annual":550000,"is_top_pay":true},"html_url":"https://alion.io/job/inflection-principal-research-engineer-model-training-post-training","json_url":"https://alion.io/job/inflection-principal-research-engineer-model-training-post-training.json","meta":{"generated_at":"2026-10-17T17:53:47Z","cache_seconds":300,"methodology":"https://alion.io/methodology","terms":"https://alion.io/terms","contact":"https://alion.io/contact","api":"https://alion.io/developers","about":"Alion is a live layer of people, companies and AI agents: who they are, whether they are real and active right now, what they do and how to work with them, readable by people and by agents and paid per call.","catalog":"https://alion.io/catalog.json","usage":{"tier":"crawler_verified","counted_by":"address","units_charged":1,"used_today":475,"day_limit":null,"remaining_today":null,"minute_limit":300,"resets_at":"2026-10-18T00:00:00Z"}},"offers":[{"id":"company.slices","title":"One company in depth, by slice","status":"live","price":{"credits":0.02,"usd":0.002,"plus_per_slice":{"credits":0.05,"usd":0.005}},"unit":"per company, plus each slice with data","note":"the employer in depth","call":{"mcp_tool":"get_company","arguments":{"id":31705},"rest":"https://alion.io/mcp/rest/get_company?id=31705"},"human":"https://alion.io/catalog?offer=company.slices&for=job%2Finflection-principal-research-engineer-model-training-post-training"},{"id":"market.stats","title":"A market slice: pay, demand and time to fill","status":"live","price":{"credits":1,"usd":0.1},"unit":"per slice","note":"pay, demand and time to fill for this role and place","call":{"mcp_tool":"market_stats"},"human":"https://alion.io/catalog?offer=market.stats&for=job%2Finflection-principal-research-engineer-model-training-post-training"},{"id":"job.search","title":"Open jobs by role, technology, place, pay and visa","status":"live","price":{"credits":0.02,"usd":0.002},"unit":"per posting in a list","note":"similar open postings","call":{"mcp_tool":"search_jobs"},"human":"https://alion.io/catalog?offer=job.search&for=job%2Finflection-principal-research-engineer-model-training-post-training"},{"id":"company.verify","title":"Is this company real and active right now","status":"pilot","price":null,"unit":"per company","request":{"url":"https://alion.io/catalog/request","method":"POST","body":"{\"offer\": \"company.verify\", \"for\": \"job/inflection-principal-research-engineer-model-training-post-training\", \"note\": \"what you need it for\"}"},"human":"https://alion.io/catalog?offer=company.verify&for=job%2Finflection-principal-research-engineer-model-training-post-training"}]}