---
title: 'Senior Full Stack Engineer at H Company'
canonical: 'https://feeny.ai/job/senior-full-stack-engineer-h-company-london-hpack26mhfaa'
type: 'job'
last_seen: '2026-10-17'
---

# Senior Full Stack Engineer at H Company

- **Company:** H Company
- **Location:** London, United Kingdom
- **Employment:** full-time
- **Work type:** hybrid
- **Posted:** 2026-10-09
- **Last confirmed live:** 2026-10-17
- **Apply:** https://jobs.ashbyhq.com/hcompany/c14ed750-6561-4daa-b75d-7a9bfb1d88f9

## Job description

You'll build the interfaces people use to run H's agents: the [H Platform](https://hcompany.ai/h-platform), where teams deploy an agent, follow it live and replay what it did step by step, and [HoloTab](https://hcompany.ai/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. H builds agents that use a computer the way a person does, in the browser and on the desktop.

## What you'll own

How 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.

## What you'll be doing

- Building the H Platform web app
- Building and improving the HoloTab extension
- Designing the live run view and replay
- Changing the Python APIs behind a feature
- Setting shared component patterns
- Making long-running workflows easier for FDEs and customers to deploy and watch

The first year Within 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.

## Your team and your users

The 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.

## What we think it takes

You're likely a good fit if you:

- Have shipped a production product in React and TypeScript as a senior engineer
- Make the API change a feature needs as well as the UI
- Write correct, concurrent code
- Handle live, async data in the UI correctly
- Enjoy working out what users actually need and designing the interface around it
- Have worked with Python

Stronger still if you have worked with:

- Chrome extensions or the Chrome DevTools Protocol
- Real-time interfaces using streaming, SSE or WebSockets
- Design systems or component libraries
- FastAPI or a similar Python API framework
- Preact and Vite

You do not need a background in Python backend development. If you match most of this but not every point, apply anyway.

## How we hire

Four 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.

Practicalities The 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.

## About H Company

## Company Overview
- **One-liner**: H Company builds a full-stack enterprise platform for deploying autonomous AI agents that can navigate digital workflows, fill forms, and complete tasks across browsers and enterprise systems.
- **Entity Type**: Private (Venture Capital-Backed; Seed stage)
- **Headquarters**: Paris, France (with a hub in London, UK)
- **Founded**: 2023
- **Founders**: Gautier Cloix (CEO), Laurent Sifre (Chair of the Scientific Committee); leadership team includes Maxime Defauw, Caroline Charra, Pierre-Louis Cedoz, and Géraldine Lafontaine [hcompany.ai/team](https://hcompany.ai/team)

## Core Business
- **Primary industry**: Business/Productivity Software; Artificial Intelligence & Machine Learning; Automation/Workflow Software [pitchbook.com](https://pitchbook.com/profiles/company/597244-24)
- **Target customers**: Global enterprises (B2B)
- **Mission**: Build AI systems that powerfully and reliably work in the real world, enabling teams to focus on what matters by letting AI do the rest [hcompany.ai](https://hcompany.ai/)

## Products & Services
- **Holo Models API (Holo3)**: Multimodal AI models designed to interpret content and operate across real-world digital workflows. Available via API for enterprise integration.
- **HoloTab**: A Chrome extension that deploys an AI agent inside the browser. It navigates websites, fills out forms, and completes tasks on behalf of the user. Users can create "Routines" to automate manual chores.
- **Autonomous Enterprise Operations Platform**: A full-stack enterprise platform combining models, advanced agents, scalable execution, and continuous learning for deploying "action-oriented AI" in production.

## Market Standing
- **Valuation**: Not publicly disclosed (Privately held)
- **Total Funding**: $220M raised (Seed Round completed May 2024) [pitchbook.com](https://pitchbook.com/profiles/company/597244-24)
- **Key Metric**: 90 employees (as of 2026); generating revenue [pitchbook.com](https://pitchbook.com/profiles/company/597244-24)
- **Notable Investors/Partners**: Accel, Aglaé Ventures, Amazon.com, Auriga Cyber Ventures, La French Tech (24 total investors) [pitchbook.com](https://pitchbook.com/profiles/company/597244-24)
- **Growth Signals**: Acquired Mithril Security (Jan 2024); maintains a wholly-owned subsidiary H.Ai Technology in London; active hiring across Research Lab, Forward Deployed Engineering, and Product Development teams

## Competitive Advantages
- **Full-stack approach**: Combines proprietary multimodal models, browser-based agents (HoloTab), and enterprise orchestration into a single platform rather than point solutions.
- **Deep research foundation**: Leadership includes former foundational AI researchers who have scaled products used by governments and the world’s largest enterprises [hcompany.ai/team](https://hcompany.ai/team)
- **First-mover in browser-based enterprise agents**: HoloTab competes in the emerging "AI agent doing work in your browser" category, differentiated by enterprise-grade reliability and routine automation.
- **Strong investor syndicate**: Backed by Accel, Aglaé Ventures, and Amazon.com — signaling confidence in enterprise AI deployment.

## Strategic Focus
- Scaling agentic AI from browser extensions (HoloTab) to full enterprise-wide autonomous operations
- Expanding the Holo Models API (Holo3) as a platform for third-party developers and enterprise integrations
- Growing the Forward Deployed Engineering (FDE) team to customize solutions for large enterprise clients
- Continuing research into reliable, action-oriented AI systems that can be trusted in production environments

## Why Work Here
- **Culture**: Described as "fast-moving, creative, and collaborative" with a "high-trust, multicultural environment." Values include integrity, curiosity, impact-first mentality, and "ship fast, learn faster" [hcompany.ai/careers](https://hcompany.ai/careers)
- **Work style**: Hackathons spark bold ideas, regular offsites, team celebrations. "Everyone’s empowered to take initiative, fix what’s broken, and own outcomes." [hcompany.ai/careers](https://hcompany.ai/careers)
- **Team composition**: A blend of deep research expertise and hands-on experience building and deploying mission-critical technology at global scale. Teams include Research Lab, Forward Deployed Engineering, and Product Development [hcompany.ai/team](https://hcompany.ai/team)
- **Locations**: Headquarters in Paris, hub in London. Roles likely span both offices with flexibility (policy not explicitly stated).
- **Role types actively hiring**: Research, Forward Deployed Engineering, Product Development [jobs.ashbyhq.com/hcompany](https://jobs.ashbyhq.com/hcompany)

## Sources
1. [hcompany.ai](https://hcompany.ai/) — Official website with product descriptions, mission, and platform overview
2. [hcompany.ai/team](https://hcompany.ai/team) — Leadership team, values, and team structure
3. [hcompany.ai/careers](https://hcompany.ai/careers) — Culture, values, and hiring philosophy
4. [jobs.ashbyhq.com/hcompany](https://jobs.ashbyhq.com/hcompany) — Active job openings
5. [pitchbook.com](https://pitchbook.com/profiles/company/597244-24) — Funding history, valuation, investors, employee count, and acquisition data

## Other roles at H Company

- [Digital Manager](https://feeny.ai/job/digital-manager-h-company-paris-cym5dpsb2ned) — Paris, France
- [Content Manager](https://feeny.ai/job/content-manager-h-company-paris-ksf7evcjs497) — Paris, France
- [Social Media and Content Strategist - Community](https://feeny.ai/job/social-media-and-content-strategist-community-h-company-paris-aq4wcyhgk9dm) — Paris, France
- [Business Partner / Executive assistant to CEO](https://feeny.ai/job/business-partner-executive-assistant-to-ceo-h-company-paris-fvv7y2xhvbg6) — Paris, France
- [Infrastructure Engineer (ML Compute) - London](https://feeny.ai/job/infrastructure-engineer-ml-compute-london-h-company-london-4ns334xrmxmc) — London, United Kingdom
- [Infrastructure Engineer (ML Compute) - Paris](https://feeny.ai/job/infrastructure-engineer-ml-compute-paris-h-company-paris-mnpet23ae537) — Paris, France
- [Product Designer - Paris](https://feeny.ai/job/product-designer-paris-h-company-paris-x0q7jf2tsexe) — Paris, France
- [Product Designer - London](https://feeny.ai/job/product-designer-london-h-company-london-88e2tsm70qwt) — London, United Kingdom
- [Technical Lead, Observability - Paris](https://feeny.ai/job/technical-lead-observability-paris-h-company-paris-53k7x9425fje) — Paris, France
- [Technical Lead, Observability - London](https://feeny.ai/job/technical-lead-observability-london-h-company-london-5dfj3p95nvqb) — London, United Kingdom