Lead Product Reliability Engineer

THE BASICS

This role pays up to £170k/year DOE + equity

Reporting to: Founding Engineer, Josh Harrison

Location: Chancery Lane, London — Mon–Thu in office, Fri WFH

WHAT ARE WE BUILDING

Fyxer is an AI Email and Meeting Assistant that eliminates admin burden for professionals in client-facing roles. Think sales, consultants, recruiters. We understand your inbox, draft replies in your own voice, and take crisp meeting notes.

We're a pure-play applied AI company, not a SaaS product with AI bolted on. We use fine-tuned open-source models, tool use, and retrieval-augmented generation. Users send 53% of the email drafts we generate.

Since launching in March 2024, we've grown from $0 to $30M+ ARR. We raised a $10M Series A and a $30M Series B in under 18 months. Our backers include Marc Benioff (Salesforce), Harry Stebbings (20VC), David Singleton (ex-CTO of Stripe), and Madrona (first investors in Amazon and Snowflake).

THE ROLE

We're hiring a Lead Product Reliability Engineer to sit within our platform team, a small, high-ownership group responsible for the infrastructure and services that keep Fyxer running as we scale, including taking ownership for billing, integrations with third-party apps, uptime and incident response.

This isn't a ticket-execution role. You'll own the reliability standard for the whole company: what good infrastructure looks like, what it takes to ship safely, and how incidents get resolved and don't repeat. You'll work across the full stack, from cloud architecture to database migrations, using deep technical knowledge and sound judgement to keep a fast-moving product on solid ground.

Some examples of what the team has achieved in the past months to get a taste:

- Migrated our billing structure in Stripe from a subscription model to usage-based billing, from technical specification through to implementation, with zero downtime.

- Redesigned the entire webhook architecture behind our Outlook integration to completely eliminate rat...