Senior Fullstack Engineer (up to £140k)

Dex; Greater London; On-site; GBP 90,000 - 130,000; Full time

Job summary

Dex is partnering with a private equity backed tech team to hire a Senior Fullstack Engineer. You’ll own major product surfaces end‑to‑end, taking ideas from whiteboards to production and measuring real user impact.

You’ll work across Python (FastAPI), TypeScript, React and PostgreSQL to design interfaces tightly integrated with internal AI infrastructure, including streaming agent execution and multilingual document search.

Qualifications

• 4+ years building and shipping production software at a venture-backed startup or top-tier tech company.
• Strong fullstack fluency across Python (FastAPI), TypeScript, React, and PostgreSQL.
• Experience building user-facing products tightly coupled to LLMs and autonomous agents.

Responsibilities

• Own core product surfaces across the entire stack from architecture to post-launch telemetry.
• Build complex user workflows on top of internal AI infrastructure, including streaming agent execution and end-to-end citations.
• Design interfaces that integrate into daily tools used by investment teams, such as spreadsheets, presentations, and email.
• Uphold code quality and performance to sustain high shipping velocity.

Skills

Python (FastAPI)

TypeScript

React

PostgreSQL

Job description

This role is with one of Dex's trusted partner companies. We work closely with their teams to truly understand their culture, goals, and what they're looking for, so we can match you with the right opportunity and give you context about the role before you commit to a process.

The role

Private equity deal teams manage billions of dollars using fragmented knowledge bases and manual workflows across Word, Excel, and PowerPoint. This team built a dedicated agentic AI platform that automates sourcing, diligence, and document authoring for multi-billion-dollar buyout and private credit funds. Backed by leading enterprise investors and scaling ARR more than 10x over the past year, they have achieved rare product-market fit in a notoriously hard-to-penetrate enterprise market. You will join as a Senior Fullstack Engineer owning major product surfaces end-to-end, taking ideas from whiteboards to production and measuring real user impact. This is not about skinning third-party API wrappers with generic frontends. You will build user experiences tightly coupled to custom underlying infrastructure, including an in-house streaming agent harness, a resumable code execution framework, and multimodal document search engines.

The work

• Own core product surfaces across the entire stack using Python, FastAPI, TypeScript, React, and Postgres, from architecture to post-launch telemetry.
• Build complex user workflows directly on top of internal AI infrastructure, including streaming agent execution, end-to-end citations, and resumable code environments.
• Design interfaces and authoring experiences that integrate deeply into the daily tools investment teams live in, such as spreadsheets, presentations, and email.
• Uphold code quality, system performance, and architectural decisions that help a fast-moving engineering team sustain high shipping velocity.

What You Bring

• 4+ years building and shipping production software at a venture-backed startup or top-tier tech company, with demonstrated ownership of features from ideation to production.
• Strong fullstack fluency across Python (FastAPI), TypeScript, React, and PostgreSQL.
• Experience building user-facing products tightly coupled to LLMs and autonomous agents, rather than just consuming basic completion endpoints.
• An appetite for deep problem domains and a high bar for craft when building for demanding finance professionals.

As part of the recruitment process at Dex, we process your personal data in accordance with our Privacy Notice for Job Applicants. This notice explains how and why your data is collected and used, and how you can contact us if you have any concerns.