More Housing Board flat buyers and sellers are choosing not to use the services of property agents, while online portals that make such transactions easier have also sprung up.
Property agencies say the impact is limited for now - but are nonetheless seeking ways to stay relevant.
At events held by property firms recently, National Development Minister Lawrence Wong highlighted the issue.
"We have opportunities but we also have to be realistic about these disruptions which are happening around the world and in Singapore," he said, referring to online do-it-yourself portals.
In 2010, only 11 per cent of all HDB resale buyers and sellers went the DIY way. Since 2013, about a quarter of all buyers and sellers each year have done so.
The trend continues. From January till May this year, 3,860 buyers and sellers - 23 per cent of the total - chose not to engage an agent.
Shifting consumer preferences could be one factor.
In 2012, 66 per cent of consumers said they were likely to engage an agent for future transactions.
Last year, this fell to 60 per cent, according to a Council for Estate Agencies (CEA) survey.
Those who take the DIY route would save on the agent's commission - usually around 1 per cent of the transaction price for buyers and 2 per cent for sellers.
PropNex Realty key executive officer Lim Yong Hock suggests a possible historical explanation, too.
Prior to regulations introduced in late 2010 to stop conflict of interests, an agent could represent both seller and buyer in the same transaction, he noted.
"If a buyer responded to an ad on his own, the agent could offer to represent him."
On paper, that would be recorded as both sides having an agent. Since dual representation is no longer allowed, independent buyers now show up in the data, he theorised.
Indeed, in 2011 - the first year after the change - the proportion of buyers and sellers doing without agents jumped to 18 per cent.
HDB buyers and sellers now have more resources to handle transactions on their own.
Buyers have a wider range of options, as they can look at listings by agents on established websites such as STProperty and SRX Property.
On other websites, there are also listings by independent sellers who choose the DIY path.
Besides classifieds sites such as Gumtree, sellers can use property-specific listing sites or apps such as DirectHome and OhMyHome.
Then, there are websites that change the relationship between home owners and agents in other ways. For instance, Yotcha is a platform on which property agents bid to serve sellers.
"Property agencies should embrace technological changes to remain relevant and competitive," said CEA director of policy and licensing Heng Whoo Kiat.
Some are doing just that. In February, OrangeTee launched its Property Agent Bank site, with agents' profiles and customer reviews.
Today, agents, too, have more resources. ERA Realty agent Kenneth Lim points to the i-ERA app which gives him on-the-go access to latest transactions, listings and so on.
The competition is not limited to online portals - the HDB also has online guides for buyers and sellers, and it holds resale seminars for the public, too. Each seminar has a maximum capacity of 100. The monthly English seminars are usually full, while the quarterly Mandarin ones attract 60 to 80 participants.
The helpfulness of HDB officers was what assured Mr Bobby Ng, 43, that it was fine to go it alone. His first DIY transaction, in 2009, had the help of an HDB officer who went through the paperwork with him.
Mr Ng, who is self-employed, completed his second DIY deal in June. He sold his Tampines three-room flat to move into a Punggol four-roomer with his wife and two daughters.
It was as easy as listing his flat online with photos, he said. He found a buyer who also went agent-free.
Even though the final selling price was $2,000 lower than his asking price of $350,000, Mr Ng felt that it was worth it. If he had engaged an agent, he would have to pay 2 per cent in commission, which could come up to $7,000.
"By going through this ourselves, we save a lot of money," he said.