The Quick Answer
For UK renters, Rightmove has significantly more listings and remains the dominant portal by a wide margin. But OnTheMarket — especially since its acquisition by CoStar Group in late 2023 — is growing fast and offers something Rightmove doesn't: early access to certain listings through its "Only With Us" feature.
The honest recommendation? Use both. And ideally add OpenRent and Zoopla to the mix as well. No single portal lists every rental property in the UK, and the one you skip could be the one that had your next home.
Rightmove — The UK's Biggest Property Portal
Rightmove has been the dominant force in UK property search for over two decades. According to its 2024 annual results, the platform recorded 2.3 billion visits over the year and commands an estimated 80-90% coverage of agent-listed properties across the UK.
Rightmove's strengths for renters:
- By far the largest inventory — over 200,000 rental properties available at any given time
- Broadest agent coverage, with over 16,000 branches listing on the platform
- Three in four UK tenants report finding their rental home on Rightmove
- Detailed filters: price, bedrooms, property type, distance, keywords, added-since date
- Familiar interface that most renters already know how to use
- Both email alerts and app push notifications for saved searches
Rightmove's weaknesses for renters:
- Email alerts are batched and delayed — often arriving hours after a listing goes live, with a hidden 14-property cap per email
- No room-share or flatshare listings (that market belongs to SpareRoom)
- Some landlords and smaller agents list elsewhere due to Rightmove's high fees — agent subscriptions average £1,530 per month
- Properties from landlords using OpenRent's free tier never appear on Rightmove
Rightmove is an essential part of any rental search. But treating it as your only resource means assuming that every letting agent and landlord in the UK pays Rightmove's premium listing fees — and they don't.
OnTheMarket — The Fastest-Growing Challenger
OnTheMarket launched in January 2015, founded by a consortium of estate agents including Knight Frank, Savills, and Strutt & Parker. Its original pitch was controversial: member agents could only list on OnTheMarket and one other competing portal, effectively forcing them to choose between Rightmove and Zoopla.
That rule was dropped in 2018 when OnTheMarket floated on the London Stock Exchange's AIM market. Since then, it has competed on merit — and since December 2023, with serious financial backing.
The CoStar Acquisition
In December 2023, US property data giant CoStar Group acquired OnTheMarket for approximately £99 million. CoStar committed £46.5 million in marketing spend in the first year alone — roughly six times OnTheMarket's previous annual media budget and more than triple Rightmove's.
The results have been significant: traffic has increased over 200%, listing volumes are up nearly 50%, and in September 2024 OnTheMarket's monthly visits briefly surpassed Zoopla's for the first time. A major deal with the Connells Group in early 2026 brought listings from over 1,200 branches — including well-known names like Hamptons, William H Brown, and Bairstow Eves.
OnTheMarket's strengths for renters:
- "Only With Us" early access — participating agents list properties on OnTheMarket 24 hours or more before they appear on Rightmove or Zoopla. For renters in competitive areas, seeing a listing a full day before most people is a genuine advantage
- Rapidly growing listing inventory — now estimated at 500,000 to 700,000 properties
- Less competition per listing due to lower user traffic, meaning your enquiry is more likely to be noticed
- "Help Me Choose" guided matching and Keywords tool for filtering by specific features
OnTheMarket's weaknesses for renters:
- Significantly fewer total listings than Rightmove — roughly half the inventory
- Lower brand awareness means some renters forget to check it
- The "Only With Us" window is typically 24-48 hours — most listings end up on other portals eventually
- Coverage varies by region; stronger in areas where agents have actively partnered with the platform
OnTheMarket vs Rightmove — Side by Side
Here's how the two portals compare on the factors that matter most to renters:
Listing volume:
- Rightmove: 1.1-1.3 million total listings, 200,000+ rentals at any time
- OnTheMarket: 500,000-700,000 total listings and growing
- Winner: Rightmove, by a substantial margin
Alert speed:
- Rightmove: email alerts batched with delays of 2-8 hours; app push notifications faster but still not instant
- OnTheMarket: offers instant alerts; "Only With Us" listings appear 24+ hours before rival portals
- Winner: OnTheMarket for early access to participating listings; similar batch delays for standard alerts
Rental focus:
- Rightmove: dominant in lettings — three in four tenants find homes through Rightmove
- OnTheMarket: growing rental coverage but no published rental-specific figures
- Winner: Rightmove for overall rental volume
Agent coverage:
- Rightmove: 16,000+ branches, 90%+ retention rate
- OnTheMarket: growing significantly post-CoStar, boosted by the Connells deal adding 1,200+ branches
- Winner: Rightmove, but the gap is narrowing
Cost to search:
- Rightmove: free for renters
- OnTheMarket: free for renters
- Winner: tie
Mobile app:
- Rightmove: well-established app with push notifications, map search, saved searches
- OnTheMarket: functional app with alerts and search
- Winner: Rightmove on maturity and features
Exclusive listings:
- Rightmove: very few genuinely exclusive listings; most agents list on multiple portals
- OnTheMarket: "Only With Us" provides a genuine 24-hour exclusivity window; an estimated 50,000-100,000 properties are listed only on OnTheMarket
- Winner: OnTheMarket for early and exclusive access
Which Should You Use as a Renter?
Both. That's the straightforward answer.
Rightmove is where the most listings are. If you had to pick one portal, Rightmove gives you the broadest coverage. But if you only use Rightmove, you miss OnTheMarket's early-access listings, you miss OpenRent's landlord-direct properties, and you miss any agents who have chosen not to pay Rightmove's fees.
OnTheMarket is particularly valuable if you are searching in a competitive area where being first matters. The "Only With Us" window gives you a genuine head start on listings from participating agents — often a full day before those properties appear on Rightmove.
For a truly thorough rental search, the minimum set of portals is:
- Rightmove — for the largest overall inventory
- OnTheMarket — for early access to certain listings
- OpenRent — for landlord-direct properties that may not appear elsewhere
- Zoopla — for agents who list there first or exclusively
If you're open to shared housing, add SpareRoom — its flatshare inventory exists on no other portal.
We covered all of these portals in detail in our full guide to Rightmove alternatives.
How to Get Alerts From Both OnTheMarket and Rightmove
You can set up saved searches on each portal individually. OnTheMarket and Rightmove both offer email alerts and app notifications. The challenge is managing them: different alert timings, duplicate listings, and the overhead of maintaining parallel searches across multiple sites.
Dwellio solves this by monitoring both OnTheMarket and Rightmove — along with Zoopla, OpenRent, SpareRoom, and PrimeLocation — continuously in one place. You set your criteria once and receive a single deduplicated alert within minutes of a matching property appearing on any of the six portals.
This means you get OnTheMarket's early-access listings, Rightmove's broad inventory, and OpenRent's landlord-direct properties all in one alert stream — without checking each site separately. Dwellio offers a 14-day free trial with no card required, at £9.99 per month after that.
Frequently Asked Questions
Does OnTheMarket have listings not on Rightmove?
Yes. OnTheMarket's "Only With Us" feature means certain listings appear there 24 hours or more before they reach Rightmove or Zoopla. Additionally, an estimated 50,000 to 100,000 properties are listed exclusively on OnTheMarket by agents who do not use Rightmove.
Is OnTheMarket as good as Rightmove?
For overall listing volume and agent coverage, Rightmove is substantially larger. However, OnTheMarket's early-access feature, rapid growth since the CoStar acquisition, and lower competition per listing make it a valuable complement. Most renters benefit from using both rather than choosing one over the other.
Why do some agents only list on OnTheMarket?
Cost is the primary factor. Rightmove charges agents an average of £1,530 per month. OnTheMarket is cheaper, and some agents — particularly smaller independents — choose to list there exclusively to reduce overheads. Others have commercial agreements with OnTheMarket that include listing exclusivity incentives.
Which property site has the most rental listings in the UK?
Rightmove has the most rental listings overall, with over 200,000 available at any given time and an estimated three in four successful tenancies originating from its platform. Zoopla is second. OnTheMarket is third but growing rapidly. OpenRent handles the most landlord-direct lettings by volume.
Can I search Rightmove and OnTheMarket at the same time?
Not through either portal's native tools — they are separate websites with separate accounts and searches. To monitor both simultaneously, you can use a property aggregator like Dwellio, which checks Rightmove, OnTheMarket, and four other UK portals in one place and sends unified alerts when matching listings appear.