It's possible the biggest future returns may come from smaller ASX shares that deliver excellent growth and execute on their potential.

Businesses that are expanding globally have a large growth runway because of how big the addressable market is. Australia is a great country, but it has a relatively small population. If a company can successfully expand overseas, then it has a bigger growth horizon.

I believe the two ASX shares below are exciting opportunities that could deliver significant returns over the next five years.

Step One Clothing Ltd (ASX: STP)

This company manufactures what it calls "high-quality organically grown and certified, sustainable and ethically manufactured underwear".

Step One's product range clearly resonates with customers, and its financial performance in FY24 was excellent. Revenue rose 29.7% to $84.5 million, and net profit increased by 43.9% to $12.4 million.

The company generated a majority of its revenue from Australia and grew sales within the country by 18.3% to $50.9 million. But, excitingly, it also has a rapidly growing presence in the larger markets of the United Kingdom and the United States.

UK revenue in FY24 rose 33.2% to $27.1 million, while US revenue jumped 261.5% to $6.5 million.

I am optimistic about the company's ability to grow in international markets in the coming years. Other countries like Canada could also make sense for future expansion. The ASX share has demonstrated the ability to grow profit faster than revenue, so long-term profit generation looks compelling.  

Siteminder Ltd (ASX: SDR)

Siteminder says it's the only software platform that unlocks hotels' full revenue potential, with its all-in-one hotel management software, Little Hotelier, making "the lives of small accommodation providers easier".

It's already a global business, with offices across Bangalore, Bangkok, Barcelona, Berlin, Dallas, Galway, London and Manila.

Siteminder is targeting 30% organic annual revenue growth in the medium term. FY24 revenue was solid, with total revenue rising by 26% to $190.7 million and annualised recurring revenue increasing by 20.8% to $209 million. Impressively, 44,500 properties are now using Siteminder, so lot of subscribers are liking its offering.

The company did make a net loss of $25.1 million in FY24, but it was a $24.2 million improvement from FY23. It made a positive underlying profit (EBITDA), with an improvement of $22.8 million to $0.9 million.

If this ASX share keeps boosting revenue at more than 20% per annum, it could grow into a significantly bigger business in the coming years. The nature of software means that its profit margins could increase significantly in the next few years and potentially surprise the market.