{"id":3339531,"url":"https://alion.io/job/refractal-senior-data-scientist-2","title":"Senior Data Scientist","company":{"id":4403779,"name":"Refractal","domain":"refractal-ai.com","url":"https://alion.io/company/refractal","size_band":"501-1000","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":null},"role":"Data Science","role_family":"Data Science","seniority":"senior","employment_type":"full_time","work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["London, United Kingdom"],"countries":["GB"],"hiring_countries":[],"hiring_countries_total":0,"salary":{"min":85000,"max":145000,"currency":"GBP","period":"year","gross":null,"usd_annual":193673},"salary_estimate":null,"experience_years_min":5,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"Embeddings","optional":false},{"name":"Fine-tuning","optional":false},{"name":"LLM","optional":false},{"name":"NLP","optional":false},{"name":"Python","optional":false},{"name":"PyTorch","optional":false}],"status":"live","first_seen_at":"2026-10-08T13:30:50Z","employer_posted_date":"2026-10-08","last_verified_at":"2026-10-29T11:19:17Z","board_verified":true,"closed_at":null,"days_open":21,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":21},"description":"About Refractal\nRefractal is an AI security company building the infrastructure organisations need to defend against autonomous AI threats. 2026 has shown that generally capable intelligence is here. The challenge now is modernising security to stop AI-enabled threats, whether they come from internal agents going rogue or from attackers using AI to become more dangerous.\nRefractal was founded on cybersecurity and AI expertise from MIT, Microsoft, NASA and the U.S. Navy. Our product lets organisations detect AI-enabled threats at low cost without sacrificing detection quality. We take a practical approach to AI risk, combining proven cybersecurity methods with frontier AI security research.\nToday, we work with governments and organisations that can't afford to get security wrong. We're backed by leading deep-tech and cybersecurity investors and are growing the team to deliver on this mission.\nThe role\nYou'll own the machine-learning models behind Refractal's detections in production, which decide in milliseconds whether an action is safe, and the analysis that shows how well they perform for each customer.\nWhat you'll do\nTrain, tune and ship classifiers for prompt injection, data exfiltration, policy violations and other risky AI activity.\n\nDesign low-latency models, including distilled and small models and rules-plus-ML ensembles.\n\nAnalyse production telemetry for drift, blind spots, false-positive cost and new attack patterns.\n\nBuild evaluations and benchmarks for our detection models, and work with security engineers to turn new attacks into training data.\n\nTurn company policies and regulatory requirements into measurable controls.\n\nSuccess in your first six months\nDetection models you own are in production, with quality metrics tracked per customer.\n\nYou've reduced false positives or latency measurably without losing detection quality.\n\nProduction data feeds a regular cycle of model improvements.\n\nAbout you: essential\n5+ years in applied ML or data science, with models shipped to production.\n\nStrong Python, PyTorch or similar, and solid statistics for evaluation.\n\nHands-on NLP and LLM work: fine-tuning, embeddings, classification and LLM-as-judge.\n\nExperience measuring fuzzy problems, including labelling, agreement and drift.\n\nClear communication of trade-offs to engineers and customers.\n\nNice to have\nExperience with adversarial ML, safety or content-moderation models.\n\nPublished work on evaluations or AI security.\n\nOur values\nRadical transparency. We believe the best work happens when everyone feels able to give and receive honest, constructive feedback.\nPublic service. We see AI security as a form of public service. Getting the AI transition right means putting the right infrastructure in place to manage the threats that come with it, and our work helps protect the institutions and services society depends on.\nFail fast. We test ideas early, seek feedback and learn quickly. We experiment rapidly and change course when something isn't working, without compromising on security.\nPragmatism, not dogmatism. We choose approaches based on how well they solve the problem. That means combining established cybersecurity methods with frontier AI research, questioning our assumptions, and changing our minds when the evidence changes.\nCompensation and benefits\nSalary: £85,000-£145,000\n\nCompetitive equity to share in Refractal's growth\n\nPension contribution\n\nPrivate medical and dental cover\n\nVisa and relocation support","description_format":"text","description_chars":3473,"description_truncated":false,"requirements":{"experience_years_min":5,"management_years_min":null,"team_size_min":null,"manages_managers":false,"education":null,"security_clearance":false,"languages":[]},"benefits":["Equity"],"hiring_locations":[],"hiring_excludes":[],"relocation_offered":true,"industries":["Artificial Intelligence","Cybersecurity","Information Security","Cybersecurity AI"],"lifecycle":[{"event":"open","at":"2026-10-27T15:00:00Z"}],"visa":[],"liveness":{"score":77,"band":"hot","label":"Hiring now","p_open":1,"p_active":0.859,"p_room":0.9,"age_days":20,"expected_fill_days":35,"reasons":["conf:2","velocity","win:mid"],"computed_at":"2026-10-29T05:49:05Z"},"pay":{"stated_usd_annual":193673,"is_top_pay":true},"html_url":"https://alion.io/job/refractal-senior-data-scientist-2","json_url":"https://alion.io/job/refractal-senior-data-scientist-2.json","meta":{"generated_at":"2026-10-29T13:42:18Z","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":20563,"day_limit":null,"remaining_today":null,"minute_limit":300,"resets_at":"2026-10-30T00:00:00Z"}},"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":4403779},"rest":"https://alion.io/mcp/rest/get_company?id=4403779"},"human":"https://alion.io/catalog?offer=company.slices&for=job%2Frefractal-senior-data-scientist-2"},{"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%2Frefractal-senior-data-scientist-2"},{"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%2Frefractal-senior-data-scientist-2"},{"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/refractal-senior-data-scientist-2\", \"note\": \"what you need it for\"}"},"human":"https://alion.io/catalog?offer=company.verify&for=job%2Frefractal-senior-data-scientist-2"}],"agent":{"mcp":"https://alion.io/mcp/jobs","mcp_open":"https://alion.io/mcp/open","next":[{"tool":"get_job","arguments":{"id":3339531}},{"tool":"search_jobs","arguments":{"company":"refractal-ai.com","detail":"compact"}},{"tool":"match_people","arguments":{"job_id":3339531},"note":"people open to offers who fit this vacancy"}],"note":"The same data through MCP tools: https://alion.io/mcp/open needs no sign-in (compact searches, postings, people); https://alion.io/mcp with an Alion account has everything. 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