About Fluidstack

Technology is the most important tool humans have found for improving the human condition, but it is not a default good. It is a lever for ideology.

Today the most powerful technology in history is being built: machines that solve problems better than humans can. The most important mission of our generation is to imbue AI with democratic values: error-correcting institutions, freedom of speech, individual liberties. AI trains and runs on massive compute clusters. Whichever ideology builds the infrastructure the fastest is the ideology that will endure. Democracy is delicate and won't survive this technology by default.

We hire people who care deeply about this problem space. If that is you, please apply!

How We Operate

Be a barrel. Full autonomy. Own things end to end, take on scope without being asked, no permission required to operate outside your core role.
Insane urgency. We drive everything forward as fast as possible.
Reason from first principles. Challenge every assumption. Zero analogy thinking, no egos, the best idea wins.
Love of the game. The frontier of AI is the most interesting problem of our time. We put in long hours at high intensity to push the frontier forward.
Build something that actually matters. If you're going to spend your time, spend it on something that matters to the world.

The Thermofluids R&D Team

Examples of key problems the team is working on

Reject more than 10 gigawatts of heat, starting now. Fluidstack is targeting 10 GW of compute in 2027 and 30 GW the year after. Every watt of it becomes heat that has to go somewhere, and no cooling team has ever been asked to open at that number rather than grow into it.
Design and build the machines, because nobody can supply them. The merchant compressor market cannot deliver at this rate, and the vendor base behind today’s chillers will not scale to gigawatts. We are taking compressor and chiller design in house, working on machine architectures nobody sells today, and going from blank sheet to production faster than this industry thinks is possible.
Own every thermofluids problem behind the fleet, not just the chiller. Working fluid and cycle architecture, heat exchangers at a scale that dominates the cost of the plant, two-phase heat transfer at the chip, and thermal energy storage. All of it is open, and whatever this team lands gets built thousands of times.

Role Scope

Define what the machine has to be, owning the cycle model that sets the working fluid and the pressures, temperatures and flows the compressor, turbine and exchangers are designed against.
Design heat exchangers with surface areas running into millions of square meters, among the largest single drivers of a data center’s physical footprint.
Design the fluid system around the machine: piping, valves, headers, relief and isolation, sized against the pressure-drop budget the cycle can afford and the pressures the fluid actually runs at.
Run the trades that decide the machine: air-side temperature rise, face velocity and subcooling. Derive the operating points from coupled exchanger ratings rather than asserted approach temperatures, so infeasible designs get caught in the model instead of in hardware.
Take the cycle predictions onto the test stand and reconcile them against measured COP, then say plainly where the model was wrong.

What We're Looking For

The below is a starting point. We always make space for exceptional people, so if you don't fit this role exactly, tell us where you would.

You’ve built a thermodynamic cycle model from fluid properties up and defended its assumptions to someone actively trying to break it.
You’ve sized real heat exchangers against published correlations, and you’ve caught a case where the correlation belonged to a different geometry than the one in front of you.
You’ve calibrated a model against a machine datasheet or test data and reported the gap honestly rather than tuning until it disappeared.
You’ve written the analysis that changed a design decision, in a form that people who never ran the code could read and act on.
You’ve sized a relief path and been the one who signed off that the system was protected.
You’ve held a result open when it was still open, instead of closing it early to be helpful.
Bonus: Vapor-compression and transcritical cycles (chillers, heat pumps, refrigeration). Propulsion and cryogenic fluid systems (feed systems, regenerative cooling, two-phase transport). Piping and relief design for high-pressure fluid systems. Real-gas properties and two-phase heat-transfer correlations (CoolProp, REFPROP, Cavallini, Gnielinski, Wang). Data center thermal architecture (CDUs, dry coolers, direct-to-chip).

We are committed to pay equity and transparency.

Fluidstack is an Equal Employment Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, national origin, sexual orientation, gender identity, disability and protected veterans’ status, or any other characteristic protected by law. Fluidstack will consider for employment qualified applicants with arrest and conviction records pursuant to applicable law.

You will receive a confirmation email once your application has successfully been accepted. If there is an error with your submission and you did not receive a confirmation email, please email careers@fluidstack.io with your resume/CV, the role you've applied for, and the date you submitted your application-- someone from our recruiting team will be in touch.