Senior Full Stack Engineer

Hcompany; Greater London; Hybrid; GBP 90,000 - 120,000; Full time

Job summary

H is seeking a senior frontend engineer to build the H Platform web app and the HoloTab extension. You’ll design live run views, replay capabilities, and determine how data flows from Python APIs to the UI.

You’ll work on cross-cutting UI patterns and shared components, ensuring a smooth end-user experience for FDEs and customers. You’ll join Product Engineering with the VP of Engineering as hiring manager, collaborating with product owners across platforms.

Qualifications

• Shipped a production product in React and TypeScript as a senior engineer.
• Able to implement API changes alongside UI.
• Write correct, concurrent UI code and handle live, async data.

Responsibilities

• Build the H Platform web app.
• Build and improve the HoloTab extension.
• Design the live run view and replay.
• Make API changes behind features.
• Set shared component patterns.
• Make long-running workflows easy to deploy and watch.

Skills

React

TypeScript

Frontend

Live data

UI design

Python

Tools

Chrome extensions

Chrome DevTools Protocol

FastAPI

WebSockets

Preact/Vite

Job 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.

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.