How much should a technical founder spend on marketing?
Short answer
Before product-market fit, close to nothing in cash and a great deal in time. Paid acquisition amplifies whatever your conversion already is, so buying traffic for a product nobody wants converts an unknown offer into a known loss. Spend money once you can state, from data, what a customer is worth to you.
The longer version
The useful way to think about this is not a budget but an order of operations. Money spent on distribution multiplies whatever your page already converts at. If a hundred visitors produce zero signups, spending until a thousand visitors arrive produces zero signups and an invoice. The multiplier works in both directions and most early products are multiplying by nothing.
What you should spend heavily is time, and specifically time in conversations rather than time on assets. A founder who spends a month rewriting their landing page in isolation has learned nothing. A founder who spends the same month showing the page to thirty people and asking what they thought it did has a rewritten page and knows why.
The threshold for spending real money is being able to finish this sentence with a number you got from data rather than a guess: a customer is worth £X to me over their first year. Until then you are not buying growth, you are buying a more expensive version of not knowing.
The full argument, with the rest of the picture around it:
Why Developers Can't Market Their Products (And What Actually Works)