Founding Backend Engineer

Build the infrastructure for the second life of Swiss fashion
Circlin is building a video-first, mobile-first secondhand marketplace designed to make buying and selling easier, safer, and more engaging.
The opportunity is simple: Swiss wardrobes are full of high-quality pieces, but today that supply is fragmented across generic marketplaces, donation bags, group chats, storage boxes and forgotten closet space. Circlin exists to make those pieces searchable, trustworthy, and desirable again.
Secondhand fashion is moving from niche behavior to mainstream commerce. Global secondhand clothing sales are forecast to reach $289B in 2026 and grow toward $393B over the next five years, with AI, better discovery, and social shopping expected to reduce friction for buyers and sellers. But most resale experiences still feel messy, generic, and transactional. We think the next generation of resale will be more local, more trusted, more brand-aware, and more engaging.
That is what we are building.

About the role
We’re looking for a Founding Backend Engineer to help build the systems at the core of the product.
This is an early, high-ownership role for someone who wants to do more than “join the backend team.” You will help define the backend foundations of the company: how we think about marketplace workflows, trust, payments, operational reliability, product velocity, and the engineering culture we build from day one.
You’ll work closely with a small founding team and help shape how Circlin handles orders, payouts, search, messaging, notifications, integrations, and the operational edge cases that matter in production.

Why this matters
Buying secondhand should feel as easy and engaging as buying new. Selling should not feel like admin work. Trust should not depend on endless back-and-forth messages. And great pieces from Swiss brands should not disappear into wardrobe dead space.
We are building the product layer that helps people buy Swiss fashion again – not by producing more, but by unlocking the value of what already exists.
If we get this right, Circlin becomes more than a marketplace. It becomes the circular commerce layer for Swiss fashion.

Compensation
This is a founding, equity-only role initially.
Before fundraising, there is no cash salary. Instead, we expect to offer 2.0%–3.0% equity, depending on experience, commitment level, scope of ownership, and final agreement.
We expect the equity to vest over a standard long-term schedule, with founder-stage terms that are fair for an initially unpaid role. Exact structure, vesting, cliff, instrument, and legal/tax treatment will be finalized as part of the agreement.
After fundraising, we expect the role to transition to salary + equity, subject to financing, role scope, and final agreement.
We want to be transparent: this is not a conventional salaried employee package today. It is for someone who is excited by early ownership, asymmetric upside, and helping build Circlin from an early but already released product into the one-stop shop for secondhand Swiss fashion.

What you’ll work on

• Design, build, and operate production backend services and workflows
• Own backend architecture decisions across APIs, workers, events, and external integrations
• Build resilient systems around payments, shipping, search, messaging, and marketplace workflows
• Define how we handle idempotency, retries, duplicate events, consistency, and payouts safely
• Help shape the engineering culture, quality bar, and long-term backend foundations of the company

You might be a fit if you

• Have strong TypeScript / Node.js backend fundamentals
• Have built and operated production backend systems from scratch
• Have hands-on AWS & Azure experience in real-world systems
• Care deeply about correctness, edge cases, and production behavior
• Communicate clearly and make sound technical tradeoffs
• Want real ownership in an early-stage company

Especially relevant experience

• Marketplace or e-commerce backends
• Event-driven systems
• Payment systems and webhooks
• Search infrastructure
• Recommendation, feed, or personalization systems

Why this role is interesting
This is a chance to be one of the first technical builders of Circlin.
You will not inherit layers of legacy systems, slow processes, or decisions made years ago. You will help make the foundational calls: how the backend is structured, how we ship safely, how we build for reliability, and how we balance speed with correctness.

You will have direct influence over:

• Core marketplace architecture
• Engineering standards and quality bar
• Product velocity
• Backend reliability and operational tooling
• The early technical culture of the company
• The way trust, payments, search, messaging and logistics work inside Circlin

This role is for someone who wants founding-level ownership and is excited by the messy, meaningful work of building a real marketplace from the ground up.

The kind of person we hope you are
You care about systems that behave correctly when things go wrong.
You think about duplicate webhooks, missing events, race conditions, retry storms, broken integrations, and user-facing edge cases before they become production incidents.
You are comfortable moving fast, but you do not confuse speed with sloppiness.
You want to build something with taste, discipline, and ambition.

Join us
Circlin is early. That means uncertainty, constraints, and a lot still to figure out.
It also means real ownership.
If you want to help build the backend of a video-first, mobile-first, secondhand marketplace from the beginning – and help create the one-stop shop for secondhand Swiss fashion brands – we’d love to talk.