Full-Stack Engineer

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 (optimized 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 organizations, 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-optimizing 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 polished, high-performance user interfaces using React and Typescript, with a strong focus on usability, speed, and design quality

Owning features end to end — from the React frontend through the Go backend, APIs, and data layer

Working across the stack on our distributed system using Go, DynamoDB, SQS, Redshift, and Lambdas

Shaping and building the next version of the Prelude API , which we strive to be industry-leading in terms of usability, performance, and functionality

Designing and building internal tools and dashboards that improve developer and team efficiency

Helping deploy and scale our fraud prevention model to hundreds of large customers

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 services

What are we looking for?

Strong experience building frontends with modern frameworks : React is ideal, Vue or similar also welcome

Solid backend skills in Go or TypeScript, with the ability to design and build reliable APIs and services

Years of experience working across the full stack, from UI to infrastructure

A preference for simplicity vs complexity, with intuition for what will scale effectively

A keen eye for product and UX — you care about what the user sees and experiences, not just what the code does

A product-led mindset, keen to code for the output and the impact

Fluent/professional English given our international team

Any experience with Rust, gRPC, or AWS serverless (Lambda, DynamoDB, SQS) is a 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.