Senior Software Engineer

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

Benefits offered by this job

Equity

Direct impact on product direction

Work with world-class founders

Job summary

A YC-backed startup in London seeks a Senior Software Engineer to join their founding team. This role involves working closely with founders, shaping the product, and making key technical decisions. You'll directly impact product direction while working in a hybrid model, splitting time between the office and remote work. Ideal candidates have strong experience in Python and TypeScript and are eager to thrive in a fast-paced startup environment. Compensation ranges from £90K to £120K plus equity.

Qualifications

• Strong commercial experience with Python and TypeScript.
• Experience with React/Next.js or similar modern front-end frameworks.
• Ability to thrive in fast-paced, early-stage environments.
• A builder who desires ownership of projects.

Responsibilities

• Work directly with founders to build and scale the product.
• Take ownership of technical decisions and architecture.
• Shape the engineering culture and technical direction.
• Build features that impact paying customers.

Skills

Python

TypeScript

React/Next.js

Job description

Senior Software Engineer – YC‑Backed Startup

Located in London. This founding team role offers £90 K–£120 K plus equity.

I'm working with an exciting YC‑backed startup in London that's just closed a multi‑million‑pound funding round and is looking for a Senior Software Engineer to join their founding engineering team.

Despite being early‑stage, they're already punching well above their weight – with paying customers onboarded and serious traction in their market. This is a rare opportunity to get in at the ground floor of something special.

Responsibilities

• Working directly alongside the founders to build and scale the product
• Taking real ownership over technical decisions and architecture
• Shaping the engineering culture and technical direction from day one
• Building features that directly impact paying customers

Tech Stack

• Python
• TypeScript
• React/Next.js

Benefits

• 3 days per week in their London office (hybrid working)
• Direct impact on product and company direction
• Work with world‑class founders backed by Y Combinator

Qualifications

• Strong commercial experience with Python and TypeScript
• Experience with React/Next.js or similar modern front‑end frameworks
• Someone who thrives in fast‑paced, early‑stage environments
• A builder who wants ownership, not just tickets to complete

If you're a senior engineer looking to step into a founding team role at a startup with genuine momentum, let's talk.

Location & Employment

• London, United Kingdom
• Full‑time, Mid‑Senior level