Senior Full Stack Developer

OnchainLabs AG; Madrid; Presencial; EUR 50.000 - 80.000; Jornada completa

Descripción de la vacante

A tech company specializing in blockchain solutions is looking for a Senior Full Stack Developer in Spain. You will work with the CTO and product teams to enhance infrastructure and develop backend services. Candidates must have strong experience in modern backend frameworks and CI/CD tools. The role offers 100% remote flexibility with occasional hybrid options. Join a well-funded startup and help redefine digital ownership.

Servicios

Family-friendly flexibility

Remote-first culture

Opportunity to work in a mission-driven team

Formación

• Proven experience as a backend or full stack developer.
• Strong knowledge of modern backend frameworks (Node.js, Python, or similar).
• Experience with Docker, CI/CD, and infrastructure-as-code tools.
• Familiarity with cloud platforms (AWS, GCP, or similar).
• Solid understanding of databases (SQL/NoSQL).
• Highly collaborative, proactive communicator (English is a must).

Responsabilidades

• Develop and maintain our backend services and deployment pipelines.
• Improve architecture, scalability, and performance across our stack.
• Analyze systems and processes to identify and track areas for improvement.
• Support the integration of APIs, SDKs, and 3rd party systems.
• Enable developers across the team with well-structured CI/CD pipelines.
• Drive documentation and transparency in all deployments.

Conocimientos

Backend development

Full stack development

Node.js

Python

Docker

CI/CD

AWS

GCP

SQL

NoSQL

English communication

Descripción del empleo

Help Shape the Future of Digital Ownership

Help Shape the Future of Digital Ownership

At OnchainLabs , we’re building WalletTwo — the invisible, intuitive wallet infrastructure powering the next generation of digital customer experiences. From loyalty systems and proof-of-authenticity to digital product passports, our plug-and-play solutions let brands integrate blockchain-backed tools without needing to speak “blockchain.”

We’ve already helped companies like Denario, zai, and CrowdTransfer launch secure, branded wallets — now we’re scaling fast. And that’s where you come in.

Your Role

We’re looking for a Senior Full Stack Developer to join us in the heart of our product engine. You’ll work closely with our CTO and collaborate across our product, design, and blockchain teams to ensure a robust, secure, and scalable infrastructure.

You’ll help us :

• Develop and maintain our backend services and deployment pipelines
• Improve architecture, scalability, and performance across our stack
• Analyze systems and processes to identify and track areas for improvement
• Support the integration of APIs, SDKs, and 3rd party systems
• Enable developers across the team with well-structured CI / CD pipelines
• Drive documentation and transparency in all deployments

What We’re Looking For

Proven experience as a backend or full stack developer

Strong knowledge of modern backend frameworks (Node.js, Python, or similar)

Experience with Docker, CI / CD, and infrastructure-as-code tools

Familiarity with cloud platforms (AWS, GCP, or similar)

Solid understanding of databases (SQL / NoSQL)

Highly collaborative, proactive communicator (English is a must)

Based in a European timezone

No need for prior blockchain dev experience — we’ve got experts for that. But curiosity about Web3 is always welcome.

Bonus Points If You

Are located in or near Spain and can occasionally work hybrid with our local team

Have experience with secure systems or fintech environments

Enjoy taking ownership of dev processes and mentoring junior engineers

What You Get

Modern, family-friendly flexibility — we believe great work happens when life works too

100% remote-first culture with optional hybrid setup if you are near our hub in Sanlúcar, Spain

Join a mission-driven team building real-world products with visible impact

Be part of a well-funded startup backed by CHF 5M and growing fast

Work alongside highly skilled, kind people who care about product, not ego

Ready to redefine the digital customer experience with us?

Send us your LinkedIn, GitHub, or whatever you’re proud of — we’ll take it from there.

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