A founding engineer is the first senior engineer a startup hires to build its product from scratch, usually before there is a CTO or an engineering team. It is not a legal category in Spain and it is not a cofounder: the founding engineer is an employee with a salary and, usually, equity. In Spain's product and startup segment, a senior engineer earns €58,000–72,000 gross a year and lead or staff engineers more than €80,000. To hire one, define the first year's scope, set salary and equity before the first interview, run a short technical process and choose how to employ the person: through a Spanish entity or, without one, through an employer of record.
What a founding engineer is
A founding engineer is an early employee, usually the first or one of the first two engineers, who builds the first version of a startup's product and makes its first technical decisions. The founding engineer writes production code every day and also chooses the stack, the architecture and the engineering practices that later hires will inherit.
The title describes a moment in the company, not a contract. Spanish employment law has no "founding engineer" category: the person signs an ordinary employment contract, normally open-ended, and the equity is granted separately through an option plan. Unlike a cofounder, the founding engineer joins after the company is founded and receives equity through an employee plan rather than as a founding shareholder.
Founding engineer vs CTO vs first engineering hire
A founding engineer sits between a senior engineer and a CTO. The founding engineer owns the code and the technical decisions of the first version; a CTO owns the technology strategy and, later, the engineering organisation; a first engineering hire in a company that already has a technical founder mostly adds delivery capacity.
| Attribute | Founding engineer | CTO | First engineering hire with a technical founder |
|---|---|---|---|
| Main job in year one | Build the first product and choose the stack | Set technology strategy, represent tech to investors | Ship features in an area of the product |
| Writes production code daily | Yes | Sometimes, less as the team grows | Yes |
| Owns architecture decisions | Yes, with the founders | Yes | No, the technical founder does |
| Manages engineers | Not at first; may grow into it | Yes, as the team grows | No |
| Typical stage | Pre-seed or seed, no technical founder or a stretched one | Any, usually once there is a team to lead | Pre-seed or seed with a technical founder |
When the founders are not technical, the founding engineer is often the person they will later consider for the CTO role. Kulturo's guide to what a fractional CTO costs covers the option of part-time technical leadership while the founding engineer builds.
When a startup in Spain needs a founding engineer
A startup in Spain needs a founding engineer when it has to build a product and nobody on the founding team can own the code full time. That is the case for non-technical founders, and also for technical founders who now spend most of their week on fundraising, sales and hiring.
A founding engineer is the wrong first hire when the product is still a prototype that an outside studio or freelancer can validate in a few weeks, or when the startup cannot yet commit to a full senior salary. For a team larger than one, Kulturo's guide to a startup's first engineering hires in Spain sets out the order of hires after the first.
What a founding engineer does in the first year
A founding engineer's first year at a startup in Spain usually covers four kinds of work, in this order of priority:
- Product build: the founding engineer ships the first version of the product and the features paying users ask for next.
- Technical foundations: the founding engineer picks the cloud provider, the stack, testing and deployment, and documents the decisions so the next engineers can follow them.
- Hiring: the founding engineer writes the technical test, joins every engineering interview and decides with the founders who joins next.
- Technical voice of the company: the founding engineer answers investors' and customers' technical questions on security, scalability and roadmap.
A candidate who has only done the first of the four in a large company may be an excellent senior engineer and still struggle as a founding engineer.
Founding engineer salary in Spain (2026)
A founding engineer in Spain is normally hired at senior or lead level. In Spain's product and startup segment, a senior engineer with 6+ years of experience earns €58,000–72,000 gross a year, and lead and staff engineers or scarce specialisations more than €80,000, according to Kulturo's salary analysis.
| Level, product and startup segment (2026) | Spain, gross per year | Madrid and Barcelona, gross per year |
|---|---|---|
| Senior engineer (6+ years) | €58,000–72,000 | €62,000–75,000 |
| Lead or staff engineer, scarce specialisation | More than €80,000 | Not published separately |
| Mid-level engineer (3–5 years), for reference | €42,000–55,000 | €48,000–58,000 |
Location moves the figure by 15–20%, according to the same analysis, with Madrid and Barcelona at the top. The bands by specialisation are in Kulturo's guide to developer salaries in Spain.
The employer pays social security on top of the gross salary. In 2026, the fixed employer rates add up to 30.65% of salary: 23.60% for common contingencies, 0.75% for the intergenerational equity mechanism, 5.50% for unemployment on an open-ended contract, 0.20% for the wage guarantee fund and 0.60% for vocational training, according to Spain's Social Security. A workplace-accident premium that depends on the company's activity is added, and contributions stop at a maximum base of €5,101.20 a month. The full calculation is in Kulturo's guide to the cost of employing a software engineer in Spain.
Founding engineer equity: vesting and cliff
Founding engineer equity in Spain is usually granted as stock options that vest over four years, with a one-year cliff. Index Ventures, in its stock option handbook for European founders, describes four-year vesting as standard practice in both the US and Europe, with no options vested during the first year and 25% vesting right after the cliff.
The size of the grant depends on the stage, the cash salary and how many engineers came before. Decide the founding engineer's grant at the same time as the option pool, so that later grants to engineers two to five keep a sensible relation to it. Stock options, RSUs and phantom shares are compared in Kulturo's guide to stock options for startup founders.
How to hire a founding engineer in Spain
Hiring a founding engineer in Spain takes six steps, and the first three happen before any candidate is contacted:
- Write the first-year scope. List what the founding engineer must ship in 12 months, which decisions they will own and whether they are expected to lead a team later.
- Set the full offer. Fix the salary band, the equity grant and the vesting schedule, and whether the role is on-site, hybrid or remote.
- Choose the employment setup. A startup with a Spanish company employs the founding engineer directly. A foreign startup without one can employ the engineer through an employer of record (EOR), which is the legal employer in Spain and runs payroll; Kulturo's guide to hiring in Spain without an entity compares an EOR, an entity and contractors.
- Search where founding engineers are. Target senior engineers who have already been early at a startup or built a product alone, not only seniors from large companies.
- Run a short technical process. Use one conversation with the founders, one practical exercise based on the product, and one session on architecture and trade-offs.
- Close with the founders. The founders present the vision, the runway and the equity in person, and answer questions about the cap table openly.
How long it takes to hire a founding engineer in Spain
Hiring a founding engineer in Spain usually takes about a month from the first call to a signed offer, plus the candidate's notice period. Kulturo's published target is 30 days from kick-off to signed offer, before the notice period, and a first batch of validated candidates in under 7 days.
Kulturo is a Barcelona tech recruitment agency through which more than 75 tech companies have hired, according to the agency. It recruits only technical and digital profiles, from software, data and AI engineers to technical leadership, and charges on a success-fee basis only. For companies without a Spanish entity, Kulturo employs the hire through its EOR partner Deel, which is the formal employer; Kulturo does not give tax advice.