Tech firms such as Google, Facebook, Amazon, Apple, Microsoft and Twitter all now have a big presence in the UK capital, and their influence is impacting the ambitions of London-based firms.
Oscar White, the CEO and founder of the travel start-up Beyonk, told CNBC: "Software developers are in higher demand than ever before, which is likely to worsen as more tech company campuses spring up around the city.
"For start-ups on tight budgets, who heavily rely on technology resource as the key enabler for growth, this presents a real challenge."
A similar sentiment has been echoed by Tom Richardson, CEO of the money management app Lumio.
He observed that it's becoming increasingly difficult to hire people for an up-and-coming company in London.
He said: "We are a start-up and with only a seed round and we cannot attract devs or great product managers. Starting salaries are mad."
Alice Bentinck, co-founder of start-up investment firm Entrepreneur First, observed that the US giants have helped to increase competition in London.
She added: "Long term I don’t think it’s a bad thing. It’s a sign London’s tech ecosystem is thriving."