Backend Engineer (Go)

About Prelude

Prelude is redefining how companies authenticate and onboard users - turning what's traditionally a cost center into a growth lever.

Our flagship product lets businesses send OTP codes with the best price-to-conversion ratio on the market, dynamically selecting the most effective channel in real time (optimised SMS, WhatsApp, and more) while actively blocking spam and fraud that legacy providers miss.

Founded in 2022 by former Zenly team members who lived the pain of broken SMS authentication firsthand, we’re already serving fast‑growing companies across Europe and are expanding into the US.

But authentication is only the starting point – we’re building the platform for trust at scale, with an ambitious roadmap of market‑defining products ahead.

Why join us

Today, we’re a team of 60 and growing, based in Paris, building products that power secure and high‑performance user onboarding for companies across the world. We believe small, highly skilled teams outperform large, fragmented organisations, and we are intentional about staying focused on impact, quality, and speed.

We operate with a flat org structure and value in‑person collaboration, which helps ideas move faster, decisions stay grounded, and teams take full ownership of what they build.

Our values

• Care – We care deeply about our customers, our teammates, and the quality and reliability of what we ship.
• Bias for Action – We move fast, test in the real world, and iterate quickly rather than over‑optimising in theory.
• Ownership – We take responsibility end to end, from identifying problems to delivering outcomes and learning from results.

What will you be doing?

• Building and scaling a distributed system using Go, DynamoDB, SQS, Redshift and Lambdas
• Building a snappy full‑stack app using cutting‑edge tech (including Next on Vercel, gRPC)
• Working on the next version of the Prelude API, which we strive to be industry‑leading in terms of usability, performance and functionality
• Ensuring that our services are scalable, extensible, reliable, and performant
• Helping deploy and scale our fraud‑prevention model to hundreds of large customers
• Developing and maintaining internal tools to improve developer efficiency
• Interacting with clients on a daily basis to assist them and build features around their needs
• Participating in on‑call rotations to guarantee the stability and reliability of our APIs

What are we looking for?

• Years of experience designing and engineering large‑scale systems
• Strong coding skills in Go – any experience with Rust, TypeScript or similar is a huge plus
• A preference for simplicity over complexity, with intuition for what will scale effectively
• A product‑led mindset, keen to code for output and impact
• Fluent/professional English given our international team
• Any experience building front‑ends with modern frameworks like React or Vue is another huge plus

What can we offer you?

• Competitive compensation package with BSPCEs
• 3 days in‑office in central Paris, with 2 days WFH, and 4 weeks of remote work per year
• 100% travel to the office subsidised
• Health insurance via Alan
• Urban Sports Club gym membership
• We will provide you with the gear you need for your role (a laptop and a phone, for on‑call rotations)
• Swile meal vouchers
• Free snacks and drinks in the office
• An annual offsite in a great location (last one was at La Pradet!)
• The opportunity to build something from 0‑1, and make an impact every day

Interview process

• Meet a member of the Talent team
• Technical assessment
• In‑person interview (system design, coding)
• Final meeting with CEO

We don’t expect you to ace all these stages; we will evaluate your creativity and how you approach difficult problems. You should consider applying even if you don’t meet all the criteria.