A BBC investigation has found the majority of adverts hosted on the websites say tenants on benefits will not be considered.
Landlords who use the platforms to rent out rooms are given the option to tick a box to exclude tenants who receive benefits. SpareRoom plans to remove the option.
The investigation found that more than 80 per cent of 59,000 listings were closed to tenants on benefits.
Analysis of other websites found that policies were in place to remove discriminatory language for adverts such as ‘no housing benefit’ or ‘professionals only’.
However, thousands of listings that appeared to be available to tenants on benefits were also advertised on OpenRent with the exclusion.
In July, landlords and letting agents were told they could no longer block prospective tenants in receipt of benefits from renting their properties after a landmark court ruling.
The judgment follows almost two years of progress in the housing industry which has seen the practice become less tolerated.
Mortgage Solutions backed a nationwide campaign led by landlord Helena McAleer to end discrimination from lenders that disallowed landlords letting to tenants claiming housing benefit in their mortgage offer terms and conditions.
As a result, NatWest and many others including The Mortgage Lender and Pepper Money changed policies to permit letting of properties to housing benefit tenants.
Speaking on the Mortgage Solutions podcast, Shelter head of partnerships Michael Stickland said the charity was still speaking to people who needed help because they had been locked out of the private rented sector by such clauses that amounted to ‘illegal discrimination’.
He added: “We’re now in position thankfully where 99 per cent of the buy-to-let mortgage market is no longer using No DSS clauses, so that’s absolutely no longer an excuse for letting agents and landlords.”
In response to the BBC’s investigation, OpenRent founder Adam Hyslop said: “We know that access to suitable properties for benefit claimants is a real and painful problem, and we want to solve the root causes of these issues.
“We’ve raised these issues in Parliament and with industry lobby groups and are working hard to address the root causes – as well as trying to combat prejudice by educating OpenRent users.
“OpenRent does not ban any group of tenants, and in the past year we have let over 25,000 properties where applications from benefit claimants were explicitly welcomed by the landlord.”
SpareRoom director Matt Hutchinson said: “After the July ruling we changed the way SpareRoom works, so landlords can only list rooms as unavailable to benefit claimants if their mortgage or insurance specifically forbid it.
“However, we’ve seen far more rooms still being listed as unavailable than the small number we expected.
“The reality is that there are almost no buy-to-let mortgages left with those clauses in them, so we’re currently in the process of removing the option to list as unavailable to benefit claimants completely.”