OnlyCat vs ZeroMOUSE (2026): Which AI Prey-Detection Cat Flap Actually Stops the Mouse?

Two companies now sell a cat flap that looks at what is in your cat's mouth and refuses entry if it sees a mouse. They solve the same problem in opposite ways. OnlyCat replaces your flap entirely. ZeroMOUSE clips a camera module onto the flap you already own.

Both advertise detection accuracy of about 99%. That number turns out to be the least useful thing either company publishes, and the gap between the two products is not really about accuracy at all. It is about what each one does when it is not sure.

Here is what the manufacturer documentation and the independent reports actually say, checked on 10 September 2026.

TL;DR — OnlyCat is a full replacement flap at £275, in stock, two-year warranty, and it pauses a single entry attempt when it sees prey. ZeroMOUSE is a ~£200 module that clips onto a flap you already own, was out of stock at both storefronts on the day we checked, carries a 60-day warranty, and lets the cat in whenever the camera cannot see its face clearly. If your cat does not hunt, buy neither and get a $108 microchip flap.

	OnlyCat	ZeroMOUSE 2.0
What it is	Complete microchip cat flap	Add-on module for a flap you own
Price	£275 base, up to £499 with accessories	~£200 UK · €199 EU · $249 US
Subscription option	~£8/mo, £299 buy-out	None advertised today
Stock (10 Sep 2026)	In stock, ships 2-3 working days	Out of stock (.com) · Sold out (.us)
Claimed accuracy	99.4%, unaudited	"Over 99%", unaudited
On an unclear read	Pauses that entry attempt	Allows entry (fails open)
Warranty	2 years	60 days
Works offline	Core door yes (lifetime tier)	Flap yes, prey detection no
Per-cat profiles	Yes, no stated limit	Inherited from host flap
On Amazon	No	No

What is the real difference between OnlyCat and ZeroMOUSE?

OnlyCat is a complete microchip cat flap with the camera and prey detection built in. It is made by a UK company, VirtualV Trading Ltd, run by brothers Martin and Tomas Rosinski in Northumberland. It reads standard ISO 11784/11785 FDX-B microchips, the same ones your vet implants, and it checks the chip on the way out as well as on the way in. Multi-cat households get a profile per cat with independent curfews.

ZeroMOUSE 2.0 is not a flap. It is a sensor module from Mousebouncer GmbH near Munich, and it mounts onto a microchip flap you must already own. It adds one thing: a camera that looks for prey. Every other rule about which cat may pass and when still belongs to the host flap. ZeroMOUSE does not add per-cat identity logic of its own, so it blocks entry when it sees prey no matter which of your cats is carrying it.

That distinction drives everything else, including the price you actually pay.

What do they cost once you add everything up?

OnlyCat sells two ways with identical hardware. The one-time purchase is £275 for the base unit, confirmed in the store page's own structured pricing data. Add the accessories most installs need, such as mounting adaptors, tunnel extenders, a weather hood or spare microchip tags, and a full bundle reaches £499. The alternative is a subscription from ~£8 a month, with a buy-out to the lifetime version at £299 that drops by £50 for each year you have already paid.

ZeroMOUSE 2.0 is ~£200 in the UK, €199 in the EU on a discount from ~€230, and $249 in the US on its separate US storefront. Worth being clear about a number in circulation: one search aggregator lists £219, but the site's own price metadata says ~£200.

Neither figure includes the host flap for ZeroMOUSE. If you do not already own a compatible microchip flap, you are buying two products.

Which one can you actually buy right now?

This is the most practical difference and it is easy to miss. On the day we checked, OnlyCat was in stock and shipping in two to three working days.

Both ZeroMOUSE storefronts were not. The EU site showed "out of stock" with an estimated restock of 12 to 15 August 2026, a date that had already passed without the page being updated. The US site said simply "sold out."

Stock moves, so re-check before you commit. But a small company with a stale restock date on its own product page is a signal worth weighing, especially against the 60-day warranty ZeroMOUSE offers versus OnlyCat's two years.

What happens when the AI is not sure?

Here is the finding that matters more than either accuracy claim.

ZeroMOUSE fails open. Its own support documentation says that if the camera cannot clearly see the cat's face, the system allows entry. Ambiguous reads are filtered out and not saved, which also means they never count against the published accuracy figure. Owner reports aggregated by podfeet.com describe that inconclusive outcome occurring around half the time in some installs, with the cat let in each time. When prey is detected, though, the flap stays locked through up to 12 verification cycles across 60 seconds.

OnlyCat handles uncertainty differently. On a positive detection, that single entry attempt pauses, and the cat can return without the prey and be admitted straight away, per its prey-detection troubleshooting guide. The cat is never stranded outside. OnlyCat says it manually reviews every detection event and feeds false positives back into training, though it has not published a split between false positives and false negatives either.

So the honest comparison is not 99.4% against "over 99%." It is a system that pauses one attempt against a system that waves the cat through whenever the view is poor.

Will ZeroMOUSE fit the flap you already own?

ZeroMOUSE claims to fit around 99% of common microchip flaps with a tunnel, and names SureFlap, SureFlap DualScan, standard PetSafe and CloserPet models.

Two exclusions are firm. The PetSafe PetPorte and the PetSafe SmartDoor use a hooded RFID reading method the module cannot replicate. And any flap with a rigid fixed roof and no tunnel has nowhere for the module to mount. Check your flap against those two before ordering, because neither is a soft limitation.

OnlyCat's install story is different because it replaces the flap. It is dimensioned to match the most popular flap on the market so it retrofits into wood, composite and uPVC doors with standard adaptors, something an independent UK installer confirms. Rectangular cutouts are 165 by 172mm, and glass installs use circular cutouts of 212 to 260mm, per OnlyCat's own FAQ.

Glass doors carry a real catch. An independent reviewer at thatcatflapcompany.co.uk points out that existing tempered glass cannot be retrofitted, because toughened glass cannot be cut after tempering. A new pane has to be ordered with the hole cut before it is toughened. That is a cost and a lead time OnlyCat's own marketing does not foreground.

For the wider category and how these sit against ordinary smart doors, our guide to the best microchip cat flaps and smart pet doors covers the non-AI options in more depth.

What do owners actually report?

Both products are reported as effective at stopping prey once installed and tuned. The friction differs.

On two Mumsnet threads about AI cat doors, one ZeroMOUSE owner reported no attempts to bring prey in during the first four days after installing, and described tagging app photos as "prey" or "no prey" to help the model learn. Another owner said their ZeroMOUSE 1.0 was brilliant at stopping live prey and the 2.0 upgrade was better still. The recurring complaints about ZeroMOUSE are not about whether it works: they are about slow support responses and a look that one poster described as flimsy or 3D printed. Both threads returned a bot challenge to direct fetching, so these themes come from indexed snippets rather than a full read.

OnlyCat owners on the same threads described the product as slicker precisely because it is integrated rather than bolted on, with a responsive UK team. Readers reporting to podfeet.com described no animals brought in after about six weeks. OnlyCat's own returns policy claims fewer than one unit in a hundred is returned during its 30-day trial.

One more piece of context. catoutofglass.com places both alongside a third entrant, the Swiss product Flappie, and declines to recommend any of them, citing limited long-term support, warranty service and replacement part availability across the whole category. This is an early market, not a settled one.

Who should not buy either of these?

Skip both if your cat does not hunt. A plain microchip flap costs two to five times less and does the job you actually need, which is keeping other animals out. Both independent retailers we read give the same advice.

Skip OnlyCat specifically if you have a tempered glass door you do not want to replace, if you need a battery-only install, since mains power is required and the backup battery only covers a safe shutdown, or if you need a documented IP weatherproofing rating. Neither company publishes one, and OnlyCat's own safety guidance says to keep the electronics out of direct weather exposure.

Skip ZeroMOUSE specifically if your flap is incompatible, if you do not already own a host flap, if you need it working this week, or if you have no stable Wi-Fi at the door. Offline, the prey detection simply stops.

There is also a company-risk question worth asking of both. OnlyCat took a £200,000 investment for 10% equity from Steven Bartlett on Dragons' Den in February 2026, on top of over £2m in cumulative revenue, so it has traction, but it is still young. ZeroMOUSE is listed as unfunded by Tracxn and runs an eight-person team near Munich. On this axis OnlyCat's one-time hardware tier is the safer pick, because its core door function continues without a subscription or a connection. The subscription tier explicitly needs connectivity to verify the subscription is live.

What should you buy if you just want a working cat flap today?

Neither of these products is sold on Amazon, and that is worth stating plainly rather than pretending otherwise. If you want prey detection, you buy direct from the manufacturer.

If what you actually need is microchip-gated entry, two flaps were in stock on Amazon when we checked. The SureFlap Microchip Cat Flap in white was ~$130, and the PetSafe Microchip Cat Door with a multi-pet 4-way lock was ~$110. Both do exactly one thing: they check the chip. A cat can still walk straight in with a mouse in its mouth, which is the entire reason the products above exist.

SureFlap's connected line, the middle tier that adds app notifications without any prey detection, showed as currently unavailable on all three Amazon listings we checked. If you want that tier, buy from surepetcare.com directly.

The verdict

Buy OnlyCat if you want one integrated product with a two-year warranty, you can pay up front or accept the subscription, and your door is not existing tempered glass. It is the better-supported option and it handles uncertainty in the way you would want: it pauses an attempt rather than waving the cat through.

Buy ZeroMOUSE only if you already own a compatible microchip flap, you want the prey layer for roughly £200 instead of replacing everything, and it is genuinely back in stock. Go in expecting a real inconclusive rate rather than the 99% headline.

Buy neither if your cat does not hunt. That is most cats, and a $108 microchip flap is the honest answer. If you are still weighing which smart pet gear earns its price at all, our breakdown of which smart pet gadgets are worth it and which are gimmicks is the better place to start.

Prices, stock and accuracy claims were all read from manufacturer pages on 10 September 2026 and move often. Check the current figures before you buy, and treat any accuracy percentage from either company as unaudited until one of them publishes a method.