{"id":3675625,"url":"https://alion.io/job/mason-ai-founding-ai-engineer","title":"Founding AI Engineer","company":{"id":4502449,"name":"Mason AI","domain":"withmason.ai","url":"https://alion.io/company/withmason","size_band":null,"is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":null},"role":"AI/ML","role_family":"AI/ML","seniority":"middle","employment_type":"full_time","work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["San Francisco, United States"],"countries":["US"],"hiring_countries":[],"hiring_countries_total":0,"salary":{"min":160000,"max":210000,"currency":"USD","period":"year","gross":null,"usd_annual":210000},"salary_estimate":null,"experience_years_min":3,"visa_sponsorship":true,"relocation_package":false,"has_equity":false,"technologies":[{"name":"AI Agents","optional":false},{"name":"Claude Code","optional":false},{"name":"Computer Vision","optional":false},{"name":"Multimodal AI","optional":false},{"name":"Post-training","optional":false}],"status":"live","first_seen_at":"2026-08-17T01:40:35Z","employer_posted_date":"2026-08-17","last_verified_at":"2026-11-04T01:44:28Z","board_verified":true,"closed_at":null,"days_open":79,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":79},"description":"Mason AI is on the frontier of agentic AI for the built world: we're the technical leaders at building AI that checks blueprints are buildable and safe.\nWe’re looking for a Founding AI Engineer to improve Mason's accuracy on our evals. You will go deep on the cutting edge of optimizing multimodal AI agents. We have similar technical problems as other agentic AI startups, stacked on top of AI for spatial reasoning and computer vision. Your work will directly affect the built environment of California within the first month of joining.\nYou will have a massive impact on the product, the company's future, and the country's, as we accelerate American construction. Join us.\nWho you are\nAn AI-pilled SWE with 3+ YoE. You know how to make mature architectural decisions for core modules, but you're AI-pilled enough to work with parallel workflows for lighter weight work.\n\nYou're mission-oriented and care about solving the housing crisis.\n\nYou love ownership and don't mind ambiguity or unblocking yourself.\n\nWhat you'll do\n50+% of your time will be spent improving the accuracy of our multimodal agents that check blueprints for building code compliance. Think post-training models and autoresearch.\n\nWear hats as needed on topics ranging from lightweight data engineering, setting up the team's coding agents for success, building internal tooling, improving the webapp, and more.\n\nBoil lakes by building new agents that extend our existing offering to commercial and multifamily housing across the country\n\nTalk to users weekly\n\nOur operating principles\nFail fast and cheap. Slugging percentage matters more than batting average.\n\nWe can make a lot of mistakes as long as we get a few things right.\n\nA written culture - we document our thinking on the few things that matter most.\n\nInternal tooling is a first-class use of time.\n\nIn-person work is a must.\n\nBenefits\nCompetitive salary ($160k-$210k).\n\nGenerous early-stage equity (0.75%-2%).\n\nFree lunch and dinner (ordered at 6 pm) at the office.\n\nFully paid health insurance with over $1000/year in employer contributions to an HSA.\n\nA 401(k) that accepts pre-tax and Roth contributions.\n\nA commuter benefits account and a monthly wellness benefit.\n\nOpportunity to shape the future of our country.\n\nInterview process\nOur interview process aims to be lightweight and respect candidates' time. We can fit it in 2 weeks.\nIntro call (30 min) - Informal chat on your interests and experience\n\nAI Coding & Technical Disagreement interviews (90 min)\nDesigned to mirror real work you'd do at Mason, you'll build a prototype for a slice of our product. AI coding tools (e.g. claude code, conductor, wsprflow) are strongly encouraged.\n\nGive us a play-by-play of a technical disagreement at work. We're looking for important disagreements with conflict.\n\nPaid work trial (3 days) - We'll set you up to run evals for our multimodal agent on our repo, and we'll ask you to generate hypotheses for experiments to run, run those experiments, and then analyze them. You'll be evaluated on your speed at running thoughtful experiments. We're flexible on scheduling, and usually run these over the weekend to minimize impact on your weekday schedule.\n\nFull-time offer\n\nNote: We are unable to offer visa support.","description_format":"text","description_chars":3250,"description_truncated":false,"requirements":{"experience_years_min":3,"management_years_min":null,"team_size_min":null,"manages_managers":false,"education":null,"security_clearance":false,"languages":[]},"benefits":["Equity","Health insurance"],"hiring_locations":[],"hiring_excludes":[],"relocation_offered":false,"industries":[],"lifecycle":[{"event":"open","at":"2026-11-03T10:56:58Z"}],"visa":[],"liveness":{"score":13,"band":"cold","label":"Long shot","p_open":1,"p_active":0.452,"p_room":0.28,"age_days":79,"expected_fill_days":25,"reasons":["conf:3","win:tail","crowd:"],"computed_at":"2026-11-04T05:01:04Z"},"pay":{"stated_usd_annual":210000,"is_top_pay":true},"html_url":"https://alion.io/job/mason-ai-founding-ai-engineer","json_url":"https://alion.io/job/mason-ai-founding-ai-engineer.json","meta":{"generated_at":"2026-11-04T05:01:04Z","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":7771,"day_limit":null,"remaining_today":null,"minute_limit":300,"resets_at":"2026-11-05T00:00:00Z"}},"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":4502449},"rest":"https://alion.io/mcp/rest/get_company?id=4502449"},"human":"https://alion.io/catalog?offer=company.slices&for=job%2Fmason-ai-founding-ai-engineer"},{"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%2Fmason-ai-founding-ai-engineer"},{"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%2Fmason-ai-founding-ai-engineer"},{"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/mason-ai-founding-ai-engineer\", \"note\": \"what you need it for\"}"},"human":"https://alion.io/catalog?offer=company.verify&for=job%2Fmason-ai-founding-ai-engineer"}],"agent":{"mcp":"https://alion.io/mcp/jobs","mcp_open":"https://alion.io/mcp/open","next":[{"tool":"get_job","arguments":{"id":3675625}},{"tool":"search_jobs","arguments":{"company":"withmason.ai","detail":"compact"}},{"tool":"match_people","arguments":{"job_id":3675625},"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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