Full-Stack Engineer

Why TheirStack?

At TheirStack, we're building one of the world's best data products on top of worldwide jobs and company data. We have tens of thousands of unique users every month, and we're growing fast.

• Small team, big impact: We're a team of 3, and tens of thousands of users rely on us every month. Sales and marketing teams at companies like Grafana, Timescale or Confluent use our data directly, and salestech companies like Clay, Reo.dev or Genesy integrate it so that all their users can access it too.
• Bootstrapped and profitable: We don't have to 50x the money of any investor to succeed. Success means keeping helping customers, solving hard problems and building a sustainable business that let us live a good, healthy life. No weekends, no 996.
• Speed is key: everything boils down to it. The product needs to be fast and efficient, and we need to ship fast and often as well.

A bit on our history

At the end of 2024, our revenue was 10x what it was at the beginning of 2024. This was due to a very good work on SEO we did at the end of 2023, which set the pace for the growth we had in 2024 and that we're still benefitting from.

In 2025, most of our effort has gone into improving the product:

• We migrated job and company searches from Postgres to ClickHouse, which let us increase the speed of some queries by up to 10x.
• We reduced the cost of getting jobs via API by 3x
• We invested heavily in the quality and depth of our docs, so that the product is as self-serve as possible. And we still have lots of work to do here.
• We added enriched, structured locations to every job. And we added the option to filter by those from a catalog of 200k+ locations.
• We improved our CI pipelines so that multiple branches can be tested in parallel, without reading from a common search database. Independend tests databases are now created on each CI run, isolated from each other.
• We added new filters to our API & UI:
  • On job descriptions
  • On the existance of given properties
  • On job URLs
  • On employment statuses, which are now standardized as well.
• We created an affiliate program, that gives every user a 30% commission on the revenue we get from their referrals during the first year.

Why are we hiring?

There are lots of opportunities in the marketing and growth area that we haven't had the time to tackle yet, but we are confident that could add fuel to our growth and are likely to have a big impact. After working hard on the product side, we want to make those bets now, while also keeping improving the product. Here are some of the things you'll help us do:

• Build new pages in our landing page, which will expose part of our datasets programatically, to match searches that potential customers are doing on search engines and LLMs.
• Build AI agents that understand the needs of every person that signs up, checks their usage of our product, and reaches out to them with tips on how to get the most value out of TheirStack.
• Let users have multiple workspaces, with different API keys in each workspace. Now a user can join other workspaces, but a user can only be in one workspace at a time, and the API key is linked to a user, rather than a workspace.
• Build infrastructure that lets us analyze massive amounts of data from new sources such as Common Crawl to detect more technologies, intents and pains companies have and that our users could leverage.
• Identify ways to add new keywords and technologies to our catalog, without having to do it manually.
• Build tools to monitor how our biggest customers are using our API, detect if their usage is going up or down, and send us alerts if the risk of churn is increasing.
• Add natural language filters to our API with function calling + build evals for it, so that our users can use English to query our jobs and companies datasets.

Your responsibilities

• Frontend: develop new pages to expose part of our datasets so that we rank on relevant topics that people are searching for on search engines and LLMs.
• Scraping: improve the infrastructure we have that enables us to have hundreds of scrapers running concurrently, 24/7.
• Backend: develop new endpoints and improve existing ones. We use FastAPI and deploy it on Render.
• Data: design database and data migrations on hundreds of millions of records. We use Postgres and ClickHouse.

You will be a good fit if you...

• You are a curious person and can learn things on your own.
• You have experience building production-ready backend and frontend systems from scratch.
• You’re familiar with testing, value code quality and maintainability.
• You are a team player, like teaching what you know and helping others grow as well.
• Ideally, you don’t have to be managed and can think of the right tradeoffs to be made to find the right technical solutions given the business context.
• You don’t need to be fluent in English, but should be able to read and write in English, as most of our customers are international.

How we work

We normally work about 8h every day, and half days on Fridays. Normally starting at around 9, but very flexible on that, whether if it’s to start earlier and finish earlier or doing the same later.

We usually have a daily to sync on what we’re going to work on during the day, but most of the days we already know what’s important and what we need to do.

We’re big fans of the Getting Real and Let my people go surfing philosophies, we practice what we preach, and we think it’s compatible with hard work.

We use AI tools like Cursor every day and leveraging them it’s one of the things that let us go so fast this year. Not only we’re fine with you using them as well, we’d love if you’re already very familiar with AI tools and show us things we didn’t know yet that let us go even faster.

The team

As the second employee at TheirStack, you’ll work closely with the founders, helping to shape the company’s future:

• Xoel Lopez: Previously at Zara.com, Narrativa, and Tinybird, Xoel specializes in data and web scraping. He kickstarted TheirStack by developing the MVP and building the core data infrastructure, the scrapers and the API, from the ground up.
• Christian Palou: Previously at Manomano.com and Zara.com, Christian focuses on UX, front-end and backend development at TheirStack. Before TheirStack, he launched TrainerStudio.io, a SaaS for personal trainers that was acquired last year.
• Pablo Durán: Previously at Fever, Sngular. Pablo specializes in full stack development (data, backend, frontend, devops, etc). He joined TheirStack in June 2024.

Compensation

40-60k€/year

Location

A Coruña

Interview process

• One 30-min chat with us to get to know you, tell you a bit more about us and the position.
• A 30-min chat to learn more about your soft skills and your technical experience.
• A take-home test to spend 3-4h on. You can use AI on it, we care more about how you think and what production-ready means for you.
• Another 30-min short call to discuss the test.

One more thing

We’re flexible about many things (salary, profit share, location), and everything is pretty much negotiable. Nothing is written in stone.

Even if you don’t tick all boxes but still think this is an interesting position, are excited about the challenges we have and think you can help us make the pie larger, apply!

How to apply

Apply through this link