Senior Fullstack Engineer (up to £140k)

Dex; Greater London; On-site; GBP 90,000 - 120,000; Full time

Job summary

Dex is seeking a Senior Fullstack Engineer to own major product surfaces end-to-end, transforming ideas from whiteboards to production and measuring real user impact.

You will build user experiences tightly coupled to in-house AI infrastructure, including streaming agent execution, resumable code environments, and multimodal document search. This role requires hands-on ownership from architecture to deployment.

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, not just basic APIs.

Responsibilities

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

Skills

Ownership

Fullstack fluency

Problem solving

Finance/enterprise domain

Tools

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.

Dex is an AI recruiter agent that helps you run your job search. Tell Dex your stack, seniority, and what you want to build. We will manage your applications and surface other opportunities that are a fit.

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.

Why apply through Dex

Most enterprise AI roles are either superficial wrapper apps or open-ended research projects with no paying users. Dex cuts through the noise, matching you directly to high-conviction engineering teams with real product-market fit and briefing you on the technical realities before you speak to them. One profile also unlocks passive matching for other high-ownership AI roles across our network.

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