Senior Core Technologies Engineer

United States Digital Space LLC; Dublin; On-site; EUR 120,000 - 150,000; Full time

Benefits offered by this job

Competitive salary and equity

Lunch provided weekdays

Regular compensation reviews

Cycle-to-Work Scheme

MacBooks provided

Flexible paid time off

Job summary

Fin is seeking a Senior Engineer to scale Elasticsearch in production and own low-level systems across our Rails monolith and adjacent data pipelines. You’ll design index strategies, improve observability, and collaborate across ingestion, databases, and build patterns to support billions of users.

You will partner with domain experts to shape technical direction, lead critical initiatives, and mentor other engineers while delivering high-impact features with reliability and speed.

Qualifications

• 5+ years experience in a production environment, with contributions to distributed systems design and architecture.
• Strong experience with at least one major datastore or search system (Elasticsearch is highly relevant).
• Good judgment around Elasticsearch in real-world systems: index design, cluster operations, migrations.

Responsibilities

• Own high-impact work on Elasticsearch at scale, including index design, shard strategy, and performance tuning.
• Collaborate with domain experts to shape technical direction and infrastructure as we scale.
• Own infrastructure aspects and autonomously execute high-impact projects across production, testing, and development.
• Contribute to all phases of software development, balancing hands-on work with strategic enablement.
• Play an active role in hiring, mentoring, and developing other engineers.
• Raise the bar for technical standards, reliability, and observability across Fin.

Skills

Elasticsearch

Backend engineering

System design

MySQL

Linux

Observability

Team leadership

Tools

Elasticsearch

Job description

What’s the opportunity?

We are looking for a Senior Engineer to join the team that enables the core technologies that Fin is built on. This role is especially compelling for engineers who enjoy scaling Elasticsearch in production and who also like working across adjacent systems such as MySQL, ingestion pipelines, and owning how they operate from low level systems engineering to all parts of our Rails and monolith.

Our team’s mission is to accelerate Fin’s growth and stability through educated and operationally excellent core technology usage. This means that we’re here to help product engineers and ML scientists build simpler, more performant product – faster. This can be through things like making low level database improvements that enhance everyone’s experience, building best in class Elasticsearch tooling, or partnering with teams that utilise any of Fin’s core technologies or our build patterns. Previous projects from the team include future-proofing our databases through sharding and building a mechanism to migrate Elasticsearch indexes for scale and profit.

We’re building a robust platform where your expertise will be applied to areas such as building a beautiful Messenger, an efficient teammate experience, a secure by default system, all while scaling the platform to billions of users and shipping two hundred new versions of the company to production every day.

Delve deeper into our engineering culture at Fin.engineering and explore our engineering values.

What will I be doing?

• Own high-impact work on Elasticsearch at scale, including index design, shard and partitioning strategy, cluster health, performance tuning, safe migrations, and operational excellence.
• Collaborate with world‑class domain experts to shape our technical direction and infrastructure as we grow.
• Deeply own aspects of our infrastructure at Fin and autonomously execute on high-impact projects – including writing application code, automating systems, improving observability and low‑level tuning of datastores used in production, test and development across Fin.
• Value agility and simplicity, just as you prioritise scalability and uptime. Our continuous deployment approach ensures focus on gradual improvements. Major accomplishments are introduced incrementally, staying under the radar with feature flags.
• Contribute to all phases of software development including ideation, prototyping, design and implementation. This role has a mix of both hands‑on development as well as strategic work and enablement.
• Play an active role in the hiring, mentoring, and career development of other engineers.
• Raise the bar for technical standards, performance, reliability, and operational excellence across Fin.

What skills do I need?

• Excellent pragmatic engineering skills.
• 5+ years experience in a production environment, with contributions to the design and architecture of distributed systems.
• Strong experience with at least one major production datastore or search system, with Elasticsearch being especially relevant for this role.
• Good judgment around Elasticsearch in real-world systems, such as index and mapping design, cluster operations, scaling patterns, performance tuning, or migrations.
• Expertise in backend technologies such as MySQL, Memcached, as well as Linux.
• Ideally, you’ve supported scaling a SaaS product in a previous role and loved the satisfaction that comes with knowing that people around the world are using something you’ve created.
• Significant, demonstrated impact that your work has had on the product and/or the teams you worked with.
• Proficient with standard software engineering methodologies, e.g. unit testing, object-oriented design, data structures, code reviews, design documentation, and utilising observability tooling.
• Understanding of modern web apps and distributed systems, along with an ability to articulate technical challenges and solutions.
• Experience as a technical lead for large multi-quarter projects and programs including defining the roadmap.
• Ability to learn quickly, iterate, unblock yourself, and persist until the right problem is solved.

Benefits

We are a well‑treated bunch, with awesome benefits! If there’s something important to you that’s not on this list, talk to us!

• Competitive salary and equity in a fast-growing start-up
• We serve lunch every weekday, plus a variety of snack foods and a fully stocked kitchen
• Regular compensation reviews – we reward great work!
• Unlimited access to Claude Code and best-in-class AI tools; experimentation & building is encouraged & celebrated.
• Pension scheme & match up to 4%
• Peace of mind with life assurance, as well as comprehensive health and dental insurance for you and your dependents
• Flexible paid time off policy
• Paid maternity leave, as well as 6 weeks paternity leave for fathers, to let you spend valuable time with your loved ones
• If you’re cycling, we’ve got you covered on the Cycle-to-Work Scheme. With secure bike storage too
• MacBooks are our standard, but we also offer Windows for certain roles when needed.

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