{"id":2188869,"url":"https://alion.io/job/h-company-senior-full-stack-engineer","title":"Senior Full Stack Engineer","company":{"id":16683,"name":"H Company","domain":"hcompany.ai","url":"https://alion.io/company/hcompany","size_band":"201-500","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":{"grade":"A","score":87,"open_postings":17,"ghost_share":0,"stale_share":0.529,"repost_share":0,"time_to_fill_p50_days":42,"computed_at":"2026-10-12T06:55:09Z"}},"role":"Backend","role_family":"Backend","seniority":"senior","employment_type":"full_time","work_mode":"hybrid","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["London, United Kingdom","Paris, France"],"countries":["GB","FR"],"hiring_countries":[],"hiring_countries_total":0,"salary":null,"salary_estimate":{"min_usd":93000,"max_usd":180000,"period":"year","method":"role_seniority_country_remote_cell","sample_n":112},"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"Chrome DevTools","optional":false},{"name":"FastAPI","optional":false},{"name":"Preact","optional":false},{"name":"Python","optional":false},{"name":"TypeScript","optional":false},{"name":"WebSockets","optional":false},{"name":"JavaScript","optional":true}],"status":"live","first_seen_at":"2026-10-09T14:33:14Z","employer_posted_date":"2026-10-09","last_verified_at":"2026-10-12T14:10:46Z","board_verified":true,"closed_at":null,"days_open":3,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":3},"description":"You'll build the interfaces people use to run H's agents: the H Platform, where teams deploy an agent, follow it live and replay what it did step by step, and HoloTab, our Chrome extension that controls the browser on its user's behalf. The work is mostly front end, in React and TypeScript, with changes to the Python APIs behind it when a feature calls for them.\nH builds agents that use a computer the way a person does, in the browser and on the desktop.\nWhat you'll own\nHow people watch, steer and replay an agent while it acts on a computer, which has few established patterns yet. You'll decide how a live run appears and plays back, how live data gets to the screen, how a feature splits between front end and API, and which components become shared standards. We'll judge the work by what ships to users, by front-end quality held in CI, and by whether people can follow and control what an agent did.\nWhat you'll be doing\nBuilding the H Platform web app\n\nBuilding and improving the HoloTab extension\n\nDesigning the live run view and replay\n\nChanging the Python APIs behind a feature\n\nSetting shared component patterns\n\nMaking long-running workflows easier for FDEs and customers to deploy and watch\n\nThe first year\nWithin three months, a feature you built, API change included, is with users. Within six, one surface is yours, such as live runs and replay or the HoloTab interface, and the team comes to you about it. Within a year, you're working across several of our products, agreeing what to build with their owners and then building it.\nYour team and your users\nThe role sits in Product Engineering, with our VP of Engineering as hiring manager. You'll work closely with the owners of the H Platform and HoloTab. Your users are our Forward Deployed Engineers (FDEs), our technical customers and the people who use HoloTab every day.\nWhat we think it takes\nYou're likely a good fit if you:\nHave shipped a production product in React and TypeScript as a senior engineer\n\nMake the API change a feature needs as well as the UI\n\nWrite correct, concurrent code\n\nHandle live, async data in the UI correctly\n\nEnjoy working out what users actually need and designing the interface around it\n\nHave worked with Python\n\nStronger still if you have worked with:\nChrome extensions or the Chrome DevTools Protocol\n\nReal-time interfaces using streaming, SSE or WebSockets\n\nDesign systems or component libraries\n\nFastAPI or a similar Python API framework\n\nPreact and Vite\n\nYou do not need a background in Python backend development. If you match most of this but not every point, apply anyway.\nHow we hire\nFour stages: a 30-minute call with our Talent team, a 60-minute coding interview, a take-home front-end exercise of about 2 hours with a 45-minute review, and a closing 30-minute conversation. The take-home is built around the kind of interface you'll be working on.\nPracticalities\nThe role is hybrid, with three days a week in our Paris or London office and a visit to the other office every four to six weeks or so. We offer a competitive package.","description_format":"text","description_chars":3053,"description_truncated":false,"requirements":{"experience_years_min":null,"management_years_min":null,"team_size_min":null,"manages_managers":false,"education":null,"security_clearance":false,"languages":[]},"benefits":[],"hiring_locations":[{"name":"France","iso":"FR","kind":"country"},{"name":"United Kingdom","iso":"GB","kind":"country"}],"hiring_excludes":[],"relocation_offered":false,"industries":["AI Agents","Foundation Models","AI Research Labs"],"lifecycle":[{"event":"open","at":"2026-10-09T17:06:46Z"}],"visa":[],"liveness":{"score":63,"band":"ok","label":"Likely open","p_open":1,"p_active":0.632,"p_room":1,"age_days":2,"expected_fill_days":42,"reasons":["conf:0","stale_co","velocity","win:early"],"computed_at":"2026-10-12T06:55:09Z"},"pay":null,"html_url":"https://alion.io/job/h-company-senior-full-stack-engineer","json_url":"https://alion.io/job/h-company-senior-full-stack-engineer.json","meta":{"generated_at":"2026-10-12T15:48:33Z","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":24989,"day_limit":null,"remaining_today":null,"minute_limit":300,"resets_at":"2026-10-13T00:00:00Z"}},"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":16683},"rest":"https://alion.io/mcp/rest/get_company?id=16683"},"human":"https://alion.io/catalog?offer=company.slices&for=job%2Fh-company-senior-full-stack-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%2Fh-company-senior-full-stack-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%2Fh-company-senior-full-stack-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/h-company-senior-full-stack-engineer\", \"note\": \"what you need it for\"}"},"human":"https://alion.io/catalog?offer=company.verify&for=job%2Fh-company-senior-full-stack-engineer"}]}