TwentyCi and Chimnie both work with UK property data, but they've built their platforms around fundamentally different questions. TwentyCi asks "who is moving, and how do we reach them?" Chimnie asks "what do we know about this property, and how confident are we?" That distinction matters when you're choosing a supplier - the overlap is narrower than it first appears.
This comparison draws on publicly available information and product documentation. It's written to help data and procurement teams understand where each platform fits rather than to pick a winner.
Who is TwentyCi?
TwentyCi is a UK-based data and marketing services company that has built what it calls the "most comprehensive property database in the UK." The company aggregates over 450 core data sources, processing roughly 30 billion factual data points per year to track property market activity and consumer behaviour.
TwentyCi's core strength is homemover data - identifying who is moving home, when they're moving, and what they're likely to spend. The company tracks the full property lifecycle from listing through to completion, building consumer profiles that power targeted marketing campaigns. Its research suggests homemovers spend £21.4 billion annually, and TwentyCi claims its campaigns deliver a £21:1 return on investment for clients.
The client base spans homeware retailers, estate agents, valuers, mortgage lenders, and financial services firms. TwentyCi's real-time property listings data feeds into market analytics products, and its consumer targeting capabilities let clients reach movers at specific stages of the moving journey - from just-listed through to recently moved.
TwentyCi is strong where marketing meets property data. It isn't, however, a property enrichment platform in the traditional sense - it doesn't offer AVMs, rebuild cost estimates, or standalone APIs for per-property risk assessment.
TwentyCi website homepage
Who is Chimnie?
Chimnie was founded by Jon Francis, a former data scientist from Google's innovation team, with the goal of making UK property data more transparent and accessible. The company operates two platforms: chimnie.com, a B2B property data bureau serving insurers, lenders, and property services firms; and chimnie.co.uk, a free consumer research site with over 150,000 users whose feedback validates the underlying data at scale.
Chimnie processes around 30 million virtual property assessments each month, drawing on hundreds of geospatial, environmental, and proprietary datasets. Its product range includes the UK Residential Property Database, the UK Commercial Property Database, a free AVM, rebuild cost estimates, address autocomplete, risk scoring, and AI training data. Delivery is via API or flat file, with published pricing starting from less than one penny per lookup.
Feature comparison
Property data depth
TwentyCi tracks property listings and transactions to build a picture of market activity - what's listed, what's sold, and at what price. It's good at the "flow" of the market. Chimnie goes deeper on individual properties - 500+ attributes per address covering physical characteristics, planning history, outbuildings, environmental risk factors, energy performance, and more. If you need to know that a property has had a rear extension approved in 2023 and sits in a flood zone 3 area, that's Chimnie's territory.
Automated valuation model (AVM)
TwentyCi doesn't offer an AVM. Chimnie provides a free AVM built on Bayesian hierarchical methods with calibrated confidence intervals. It produces separate listing and sale price estimates at micro-postcode granularity, and it's the only UK AVM that ingests a full national dataset of planning permissions - accounting for extensions, conversions, and outbuildings that haven't yet triggered a new transaction or EPC.
Homemover and marketing data
This is TwentyCi's home ground. Its platform identifies consumers at each stage of the moving process and builds targetable profiles for direct mail, digital advertising, and campaign management. The depth of behavioural data - what movers buy, when they buy it, and through which channels - is genuinely strong. Chimnie doesn't operate in this space. It's a property data supplier, not a marketing platform.
Rebuild cost estimates
Chimnie provides rebuild cost estimates with confidence intervals, finish-quality segmentation, and decomposed materials and labour costs at regional level. TwentyCi doesn't offer rebuild cost data - it isn't part of their product scope.
Risk and environmental data
Chimnie covers flood, subsidence, crime, pollution, traffic, energy performance, roof condition (via satellite imagery), tree-fall risk, solar panel detection, garden boundaries, and listed building status. TwentyCi's datasets are built around market activity and consumer behaviour rather than environmental or property-level risk. If you're pricing insurance or assessing climate exposure, TwentyCi's data won't get you there.
Commercial property data
data
Chimnie offers a dedicated commercial property database covering offices, retail, warehouses, and mixed-use properties. TwentyCi's focus is residential market activity.
Market analytics
TwentyCi provides real-time market analytics drawn from its listings data - tracking supply, demand, price movements, and regional trends. Its HomeMover Index and related products give clients a view of market momentum that's useful for strategy and planning. Chimnie provides sales history and local market statistics but doesn't track live listings or market flow in the same way.
API access and integration
Chimnie offers documented REST APIs for all its products, with a free AVM endpoint, free address autocomplete, and full API documentation available without a sales call. TwentyCi's data is typically delivered through managed campaigns, reports, or bespoke data feeds rather than a self-service API. If you need to call a property data endpoint from your own systems in real time, Chimnie is built for that; TwentyCi isn't.
Pricing
and access
Chimnie publishes its pricing - lookups from less than one penny per property, with the full residential database starting at around four thousand pounds per month. TwentyCi doesn't publish pricing. Its engagements are typically structured as campaign or data-licensing agreements, negotiated on a client-by-client basis. For teams that want to test quickly and scale on their own terms, Chimnie's transparency is a practical advantage.
AI training data
Chimnie property data API homepage
Chimnie offers a UK Property Images database with over one billion property images for generative AI training. TwentyCi doesn't offer a comparable product.
Where TwentyCi is stronger
TwentyCi is the better choice when your goal is reaching consumers who are moving home.
Its homemover identification and targeting capabilities are purpose-built for marketing. If you're a homeware retailer, a removals company, a broadband provider, or any business that profits from catching people at the point of a house move, TwentyCi's data and campaign services are directly relevant. The £21:1 ROI claim is backed by campaign case studies across retail, financial services, and home improvement sectors.
TwentyCi's real-time listings data also gives it an edge in market analytics - tracking what's coming to market, how long it sits, and how prices are shifting across regions. For estate agents, portals, and property analysts tracking market momentum, this is valuable.
The managed-service model suits organisations that want a data partner to run campaigns on their behalf rather than building in-house data pipelines. TwentyCi handles the targeting, the creative, and the delivery.
Where Chimnie is stronger
Chimnie is the stronger choice when you need to know about properties rather than people.
For insurance use cases - underwriting, pricing, claims validation, fraud detection - Chimnie's data is purpose-built. Rebuild cost estimates with confidence intervals, risk scoring across dozens of perils, and pre-fill APIs are designed around insurance workflows. TwentyCi doesn't play in this space at all.
For mortgage brokers and sourcing platforms, Chimnie's free AVM makes it practical to run a valuation on every case rather than reserving it for edge cases. The planning data and outbuilding mapping catch property changes that other valuation models miss - extensions, loft conversions, and garden buildings that haven't yet appeared in transaction data.
Chimnie's API-first approach means you can integrate property data into your own systems in hours, not months. The documentation is open, the pricing is published, and the free tier lets you evaluate without a procurement cycle.
The consumer platform (chimnie.co.uk) creates an unusual feedback loop - over 150,000 homeowners checking and correcting data about their own properties, which feeds back into the B2B datasets. TwentyCi doesn't have an equivalent mechanism for ground-truth validation.
Who should choose which
Retailers, home services, and consumer brands targeting people who are moving home should look at TwentyCi. Its homemover identification, behavioural profiling, and campaign management are built for exactly this purpose. Chimnie won't help here.
Insurers, MGAs, and reinsurers should look at Chimnie. The property risk data, rebuild cost modelling, and insurance-specific APIs are directly relevant to underwriting and pricing. TwentyCi's marketing-focused data isn't built for these workflows.
Mortgage lenders and brokers will likely find Chimnie more useful for property-level enrichment and valuation, though TwentyCi's market analytics could supplement strategic planning and customer acquisition.
Estate agents and property portals might find value in both - TwentyCi for market intelligence and lead generation, Chimnie for detailed property reports and valuations to share with clients.
Proptech firms and data science teams building property-related products will find Chimnie's APIs, training data, and per-lookup pricing more practical for integration. TwentyCi's managed-service model is less suited to self-service product development.
Conclusion
TwentyCi and Chimnie aren't competitors in any meaningful sense. TwentyCi is a marketing data and campaign business built around the UK property market. Chimnie is a property data bureau built for technical integration into insurance, lending, and property services workflows. The question isn't which is better - it's which problem you're solving.
If you need to reach people who are moving home, TwentyCi is purpose-built for that. If you need to understand properties - their value, their risk, their physical characteristics - Chimnie is where that data lives. Some organisations will use both, and that's a perfectly reasonable outcome.
Chimnie's pricing is published, the free AVM is live, and the API documentation is open - so working out whether it fits your needs takes minutes, not months.
