Oferta sólo disponible en Inglés
Oferta cerrada el 20/03/2024

Senior SRE

🎯 Product🛸 Startup🏠 Hybrid⛓️ Blockchain🏝️ Unlimited holidays💂 English

Are you into the world of Web3, non-fungible tokens (NFTs), and blockchain?

In the digital universe of Crossmint, which is sort of like the Avengers of blockchain in Marvel language, they're on the hunt for their very own Iron SRE, a software genius who can wield technology like Tony Stark himself.

They're crafting APIs and tools as mighty as Thor's hammer and defending the network against spam and deepfakes, all in true "Team Rocket" style.

¿Qué harás?

You might have heard about NFTs. Digital collectibles (often with 🙊🙈 themes) that people trade for absurd amounts of money online. Pretty cool, right? NFTs are much more than that; they're the leading digital standard for representing ownership (what MP3s are for music, NFTs are for property titles) and are used for use cases ranging from digital collectibles and gaming to tickets, loyalty programs, and even boats and houses.

The standard has skyrocketed, and now it's being used by many of the world's leading companies and brands, like MasterCard, Red Bull, Air Baltic, Tomorrowland... all of them are Crossmint clients, of course.

But... what does this have to do with them? 🧐

Well, at Crossmint, they're experts at making digital assets accessible to everyone. How? They have the leading platform for creating, safeguarding, and selling NFTs, using traditional and easy-to-use REST APIs and JS SDKs.

Their goal is to make this technology accessible to developers without any prior knowledge of cryptography, as well as to their users. They enable anyone to create, sell, and distribute NFTs in minutes with their APIs, wallets, and trustless access without needing wallets or cryptocurrencies.

It's an enterprise-level leading platform for integrating blockchain assets into applications. Focusing on ease of use, Crossmint allows for end-to-end use cases to be created without requiring prior experience in blockchain or cryptocurrencies, while making blockchain invisible to end users.

They offer tools for creating, distributing, and selling digital assets, as well as custody and non-custody wallets to store them.

Over 30,000 companies and developers trust Crossmint, including Fortune 500 and major companies like Mastercard, Microsoft, Etihad Airways, Red Bull, Adidas, Asus, and many more.

Important web3 brands like Phantom, Manifold, Rarible, and creators like Refik Anadol also rely on Crossmint. While they don't only have these products, they are indeed the main ones: wallets, minting tools, and payment gateways for NFTs.

  • Wallets:

Crossmint offers a house-branded integrated wallet, trusted by developers like Mastercard and Red Bull, and a wallet accessible from, which aggregates user-integrated wallets. With this product, you can instantly add web3 capabilities to your website or application, creating wallets for existing users via API and for new users upon registration. You can also create quick plug-and-play activations that don't require interface work.

You can get all the infrastructure you need to get started in minutes, with enterprise-level reliability and support, eliminating RPC, indexers, aggregators, payers, and any other blockchain infrastructure.

  • Minting Tools:

Crossmint provides a set of APIs for creating, updating, deleting, and managing tokens, all accessible through REST APIs and a no-code panel, available on all major chains. You can create your first NFT in less than 5 minutes and have the same code scaled to millions of NFTs, without worrying about smart contracts, key security, or scaling hassles.

  • NFT Payment Gateway:

Crossmint helps clients increase their sales up to 3 times with a 10-minute integration by allowing people to buy their NFTs with a credit card or any cryptocurrency, even if they don't have wallets. Crossmint offers the most battle-tested NFT payment product on the market, powering most major launches, launch platforms, and markets on all chains, such as Manifold, Magic Eden, Tensor, and more.

As you can see, they have everything set up so well that the next step is to grow the team to give even more love to the product if possible.

Tu evolución

Tu primer día

En 1 mes

During the first few days, you'll have time to set up your environment, undergo various trainings, and familiarize yourself with our processes. Everything here runs smoothly, and since they'll trust in your abilities, you'll likely be assigned a task and have it deployed to production as early as the first week.

By the end of the first month, they trust that you'll have launched several impactful initiatives, benefiting both users and the business. It's a fantastic opportunity to become acquainted with what we have set up and to make meaningful contributions right from the start.

Tus responsabilidades

  • You'll lead projects from conceptualization to deployment, ensuring a comprehensive and successful approach to executing initiatives, and demonstrating your project management and technical leadership skills.

  • Maintain high-quality, robust, secure, and efficient code for the infrastructure, ensuring its correctness, security, efficiency, and maintainability, contributing to the success of the development team.

  • Design and build highly available, efficient, scalable, and flexible software for the backend, ensuring optimal performance and an exceptional user experience.

  • You'll be responsible for designing, implementing, maintaining, and optimizing the infrastructure. You'll primarily work on Azure, databases, Blockchain RPCs, etc., using IaC (Infrastructure as Code).

  • Ensure the smooth operation and stability of the architecture, including database performance, memory leaks, metrics, alarms, etc.

  • Ensure the continuous maintenance of the payment infrastructure, prioritizing security, performance, and site reliability to provide a seamless experience to users.

  • Automate your work and that of other colleagues through scripts and artificial intelligence.

  • Provide technical contributions to the formulation of strategies and architectures aligned with the company's payment-focused objectives.

  • Resolve complex technical challenges related to backend software engineering, cryptography, and blockchain infrastructure, contributing to the development of innovative solutions.

  • Participate in an agile work environment, actively engaging in implementing improvements in the infrastructure, driving efficiency, and innovation.

  • Mentor and support some team members, sharing your experience and knowledge to foster professional growth.

  • Develop documentation on architecture and design, both individually and collaboratively with the team, providing clear guidance for solution implementation.

  • Participate in paid on-call shifts (once or twice per quarter) as part of On-Call duties, ensuring system availability and stability.

¿Cómo lo harás?

Their flagship product (credit card payment for NFTs) has surpassed the product-market fit and processes millions of dollars in GMV. Their other offerings range from beta to on the path to product/market fit. The white-label solution is in beta, but the minting API is rapidly approaching product-market fit, as over 100,000 NFTs have been minted using it.

What will the day-to-day look like? 📅

You'll join the Developer Platform team, responsible for maintaining the development console, API infrastructure, and internal tools. Their daily process is agile, with two-week sprints and starting the week with sprint planning that aligns with the objectives and OKRs they aim to achieve each quarter.

You'll work on projects to expand and support these products, as well as launching others related to them. Therefore, among your main tasks will be:

  • The developer console, where all their products are installed and configured.
  • Hosted sales experiences, allowing project owners to set up websites to sell their NFTs without any coding knowledge.
  • Infrastructure for the team, including our comprehensive CI/CD pipeline, tested automation infrastructure, databases, etc.

They communicate using tools like Slack and Linear to resolve questions, issues, and stay in touch with each other.

The stack they work with is based on Node.js, React, Next.js on Vercel, TypeScript, Ethers.js, Solana (web3.js), MongoDB, AWS, Azure, Github Actions, and Cypress for CI/CD.

Straight to the point, what do they expect from me? 👩🏾‍🎤

As Lead SRE, they expect:

🦸🏾‍♀️ Strong technical leadership.

🏗️ Extensive knowledge of Design and Architecture.

🤔 A proactive and solution-oriented mindset.

⚖️ Exemplary quality and good documentation.

👨‍👩‍👧‍👦 Mentoring and teamwork.

🗣️ And, close collaboration with other departments.

You'll be at the forefront of software and infrastructure development to redefine Non-Fungible Tokens (NFTs) and other digital assets. You'll be leading projects, designing, building, maintaining, implementing, optimizing, providing ideas, mentoring, etc. Likewise, you know, the typical Lead stuff!

¿Cuándo trabajarás?

Be like water, my friend!

They don't have fixed hours, so you'll be free to organize your day as it suits you best. You can take the dog for a walk and take the cats to the vet to get their nails trimmed. No more excuses!

However, every Wednesday, the all-hands is meeting where all Crossmint members gather to catch up on everything related to the company. To ensure that the entire team, spread between the US and Spain, can attend the all-hands, they'll ask the Spanish team members to start their day a little later, and the US team members to start a little earlier. All for the sake of love and good communication! 🤍


22 días


On-Call Shifts:

Along with the rest of the team, you'll be part of a paid on-call shift for 8 consecutive days, each lasting 12 hours. Typically, these shifts occur every six to eight weeks. These shifts generally involve monitoring and responding to critical notifications impacting the platform or end users. Notifications are received through Squadcast and Slack. If there's something you can't resolve, no worries; fix what you can, and if needed, escalate to someone with more knowledge or experience.

¿Dónde trabajarás?



From your home, most of the time.

They have hacker-house-style offices located in Miami and New York, and a coworking space in Madrid. Even though Miami and New York may be a bit far, you'll always have París Madrid.

¿Con quién trabajarás?

You'll be part of the Engineering team, consisting of 7 people, which in turn is part of a larger group of 29 individuals including Developers, QAs, Designers, DevOps, Product Managers, and Security experts, all eagerly awaiting you with open arms. And a virtual and/or in-person coffee ☕.

Some of the people you'll interact with the most daily are:

Rodri Fernández Touza (Cofounder). Rodri sounds like quite the wild spirit! He's lived a life of randomness, from experiencing homelessness to training as a Zen monk, achieving a Guinness World Record, trekking through half of Korea without a penny, crashing a motorcycle in the jungle, and finding his way back to civilization five days later. And would you believe it? He even holds a Nigerian royal title! When it comes to conversation topics, you can pick Rodri's brain about meditation, extreme adventures, extensive reading, the exploration of silence, climate technology, and space. He's got a wealth of experiences and interests that make for some truly captivating discussions!

Alfonso Gómez - Jordana (Co-founder) Madrid-born, Alfonso has spent many years in Silicon Valley. At Google, he served as the Product lead behind the creation of the "I'm not a robot" widget (though, to be clear, it was someone else who later added the images of traffic lights), as well as Firebase Authentication. He also founded AI SDKs (Google Assistant SDK + Actions on Google). Alfonso was also among the earliest employees at WhatsApp (its third Product Manager), where he led teams of over 60 people, contributing to the app's growth from 1,000 to 2,000 million users. Outside of work, he's passionate about cooking paellas (hence the name of the parent company, Paella Inc.!). The highest-rated paella restaurant on Google Maps in San Francisco was his home for a while (and may still be to this day!).

Ángel Pina Canelles (Principal Software Engineer). Ángel loves building things and lives with three one-eyed cats. He changes the color of his hair every two months and is a three-time world champion of Jugger! He's passionate about aerial silks and hoops. There's no doubt he's full of interesting tidbits!

¿Qué piden?

In their wish list to "San Juanan," the Manfredian deity celebrated every June 2nd, they have requested a Lead SRE who meets a series of requirements. I won't lie to you, they are looking for a very top-notch profile, hence the salary range up to 100k.

So, if you're interested in participating in this selection process, you need to come prepared with...

  • They are looking for someone with extensive professional experience in developing production systems, with a focus on infrastructure and site reliability engineering. They're seeking a Principal, meaning someone with at least 7-8 years of experience and a solid track record.
  • A strong command of cloud infrastructure, especially on platforms like Azure, GCP, and AWS. You should know them like the back of your hand.
  • Experience with NoSQL databases like MongoDB and scaling tools for SQL databases like Planetscale, as well as cloud DB services like Upstash (Redis). 
  • Also, experience with state management and orchestration systems like
  • Advanced knowledge in a modern programming language, particularly in backend infrastructure development (e.g., JavaScript, Python, Java, Rust, Go, Solidity, Kotlin, etc.). They primarily work with the JavaScript ecosystem.
  • They're seeking the mindset of someone from an academic background, specifically in Computer Engineering or a similar field, as they need deep knowledge in specific areas.
  • A high level of English proficiency, fluent enough to make you comfortable in a fully English-speaking work environment.

If you want to aim for top grades...

  • Previous experience in security/cryptography,
  • Knowledge of blockchain/smart contracts,
  • Previous interaction with NFTs.



  • Azure
  • AWS
  • Google Cloud
  • Github Actions
  • JavaScript

Estaría bien

  • OpenApi
  • Go
  • Rust
  • Python
  • MongoDB
  • Redis

Suma puntos

  • Web3
  • Ethereum

Otras habilidades


  • Adaptabilidad al cambio
  • Liderazgo
  • Proactividad

Estaría bien

  • Aprendizaje Continuo
  • Tolerancia a la incertidumbre
  • Resistencia a la frustración

Suma puntos

  • Atención al detalle
  • Gestión de equipo
  • Capacidad de mentorización



¿Qué ofrecen?


Hasta 100K



🏖️ Unlimited vacation. Repeat after me: un-lim-it-ed.

Flexible working hours.

👩🏾‍💻 Necessary equipment for comfortable work (laptop) as well as a quarterly bonus of €135 for any additional equipment you may need (extra monitor, keyboard, mouse, etc.).

🛫 Company-paid trips for meetings and team building events. They have 2 trips per year, each to a different location around the world, and possibly some trips to Miami and/or NY depending on the team's needs.


Presupuesto para Conferencias
Ayuda con el transporte
Dinámicas y eventos de teambuilding
Vacaciones Extra
Pack de bienvenida
Retribución Flexible

Capacidad de transformar parte del salario en pagos en especie como: cheques-guardería o Tickets Restaurant.

Posibilidad de elegir equipo

What the FAQ?

Nope. Due to administrative reasons, they are focusing on profiles of individuals residing in Spain. In fact, the offer requires semi-presentiality in Madrid.

The selection process will consist of 4 phases:

  1. Coding challenge.
  2. Architecture interview.
  3. Coding interview.
  4. Founder interview with Alfonso 😉