Senior Engineer

Duffel; Greater London; Hybrid; GBP 110,000 - 170,000; Full time

Benefits offered by this job

Equity

Work from anywhere

Private Healthcare

Travel allowance

Matched Family leave

Sabbatical

Office in Shoreditch

Job summary

Duffel in London is seeking a Senior Software Engineer to help shape both the product and the team building it. This is a hands-on role combining coding with technical leadership.

You will work on the core API powering travel bookings, design scalable systems, and mentor teammates while collaborating with product and design. This hybrid role carries a Shoreditch/Liverpool Street presence and a competitive package with equity and benefits.

Qualifications

• Experience designing and shipping APIs at scale.
• Ability to turn loosely defined problems into concrete technical plans.
• Strong systems thinking across the stack and tradeoffs.
• Hands-on coding with ownership of production systems.
• Experience mentoring engineers and raising the bar for the team.

Responsibilities

• Define and shape product and technical direction.
• Build and ship robust, scalable features in a hands-on role.
• Mentor engineers and help their professional growth.
• Collaborate across product, design, and other teams to align architecture.

Skills

API design

Systems thinking

Hands-on coding

Mentoring

Clear communication

Tools

Elixir

Phoenix

Kubernetes

Google Cloud Platform

Job description

Senior Software Engineer

London | Full-time | Hybrid | Shoreditch/Liverpool Street

Create the Future of Travel With Us

Whether it's visiting the people closest to us, starting an exciting adventure, or a career-defining business trip, travel is essential.

Yet we've all experienced the aches and pains of getting to our destination.

More than 4 billion airline passengers rely on technology that hasn't kept up with modern expectations. That's why we're rebuilding the infrastructure that underpins the travel industry - simplifying systems and building tools that will make the future of travel effortless.

We were part of Y Combinator S18's cohort and we're backed by Benchmark, Blossom, Index Ventures, and Kima Ventures - a fantastic set of investors that has helped build some of the world's largest companies.

Our London team is growing, and we're looking for a Senior Engineer to help shape both the product and the team building it.

Engineering at Duffel

We're building tools to simplify travel distribution, search, and booking through one seamless API. The technical challenge? Design a world class API, then integrate it with a vast number of travel providers - each with different systems and requirements - whilst delivering a fantastic developer experience.

We work with Elixir, Phoenix, Kubernetes, and Google Cloud Platform, but we value strong engineering fundamentals over specific tech experience.

As a Senior Engineer, you won't just execute against a spec - you'll help define what gets built and how. You'll take on ambiguous problems, shape technical decisions across teams, and set a bar for quality that others follow.

You'll Thrive Here If:

• You've designed and shipped APIs at scale, and have a clear point of view on what makes a great one


• You can take a loosely-defined problem and turn it into a clear technical plan, working independently - weighing technical rigour against business impact along the way


• You think in systems: you can trace how a decision in one part of the stack ripples into others, and design with those knock-on effects in mind


• You want to keep writing production code as a senior engineer, not move away from it - this role is hands-on for the long run, not just at the start


• You've mentored engineers or helped them do their best work, and take real satisfaction in others reaching the bar you hold yourself to


• You communicate clearly, articulating what you're working on, why, and the reasoning behind your tradeoffs, in a structured way, to a variety of internal and external stakeholders.


• You thrive collaboratively - you believe in your methods but stay open to feedback and suggestions, and know when to stand by your approach and when to compromise


• Bonus: Experience in travel, flights, hotels, or cars

What You'll Get:

• Competitive salary + equity (you'll own part of Duffel)


• Work from anywhere policy


• Private Healthcare


• Duffel travel allowance (use what we build)


• Matched Family leave


• Sabbatical programme (3 months full pay)


• Office in Shoreditch + regular team socials

Why Now Matters

You’ll work on the core API powering millions of travel bookings, with real influence over its direction. Early-stage role = outsized impact on how we build and scale, and a seat at the table for the technical decisions that will define the next phase.