At Mosaic Conseil, we function as a specialized remote workshop dedicated to the reconstruction of business artifacts. We are currently working with a major Spanish financial services group to modernize their internal pricing and risk models. This is not a project about aesthetic updates or slide decks.

Instead, we are dismantling complex financial structures to rebuild them with better evidence and clearer logic. As a Junior React Developer, you will help us turn these refined models into functional, resilient tools that the client can use to make better decisions.

About Mosaic Conseil Mosaic Conseil is a boutique firm that operates entirely in a remote environment. We take apart business plans, pricing grids, and diligence files, then put them back together against the evidence of the invoice ledger. Our process is personal and focused. We do not work on standing retainers, and we do not produce decorative presentations. Instead, we return the same artifact you sent, redrawn by hand or rebuilt in code, and supported by a written argument.

We keep the workshop small on purpose to ensure that the people who do the work are the same people who answer the telephone when a client calls. We focus on four specific rooms: financial services, industrial networks, growing software companies, and healthcare systems. By remaining independent and remote, we stay focused on the evidence at the floor of the business.

What you would do In this role, your primary task is to translate complex financial logic into clean React components. You will not be building generic landing pages: you will be building tools that allow users to interact with deep data sets and risk models. Your work will directly support our engagement with the Spanish financial services group mentioned earlier.

- Building interactive dashboards and calculators that reflect real world financial constraints.




- Translating logic from Excel models and written arguments into functional React applications.
- Participating in our builder and challenger model, where you either build a component or argue against the logic of one built by a peer.
- Writing clear, concise documentation for every piece of code you produce.
- Testing assumptions within the code to ensure that a pricing grid or valuation tool remains accurate under stress.
- Collaborating with our analysts to ensure the front end correctly represents the underlying financial evidence.
- Maintaining a high standard of code readability so that our tools can be supported via telephone for ninety days after delivery.

Helpful background We are looking for someone at the beginning of their professional career who values intellectual honesty and precision. You do not need a decade of experience, but you do need a foundational understanding of how to build things that work. This position is fully remote, so strong written communication is essential.

- Basic proficiency in React and modern JavaScript.
- Familiarity with state management and how to handle data flow in complex interfaces.
- A genuine interest in how businesses work, particularly in the financial services sector.
- The ability to read a logic statement or a spreadsheet and understand the intended outcome.
- Comfort with receiving direct feedback and participating in rigorous peer reviews.
- Self discipline to manage your own schedule in a remote setting without constant supervision.




- A preference for simple, functional code over complex or clever solutions.

How we work Our workshop is built on deep work and autonomy. We do not have meetings that we did not schedule for a specific purpose. We communicate through written arguments and focused calls. Every file we produce carries two names: the builder and the challenger. This ensures that every assumption is tested before a file closes. Working here means you are responsible for your own output. There are no layers of management between you and the work. Because we are 100 percent remote, we rely on clarity and evidence rather than office presence. We value the time spent on the bench, getting the details of a model right, over the performance of looking busy.

What the role offers This is a full time, permanent position that offers a competitive salary for the market and the role. You will have the opportunity to work on high level financial problems for significant international clients, like our current Spanish partners, within a small and supportive team. The remote nature of the work provides genuine autonomy and a lack of corporate theater.

You will be given the space to focus on one problem at a time. We believe that professional growth comes from the discipline of rebuilding things until they are correct. You will learn to see the architecture of a business through its ledgers and artifacts, gaining a perspective on finance that few entry level roles provide.

Our commitment to a small workshop means that your contributions are visible and meaningful. We do not hire for the sake of growth, but for the sake of the work. When a file is closed and delivered, we stand behind it with a telephone number that answers for ninety days, ensuring that what we build actually lasts in the real world.

📌 Junior React Developer (Madrid)
🏢 Mosaic Conseil
📍 Madrid