Chimnie and Ordnance Survey occupy different layers of the UK property data stack, and for good reason - Chimnie is a partner that builds on top of OS data to deliver property intelligence. Ordnance Survey provides the foundational geospatial and address data that underpins much of the UK's property ecosystem. Chimnie takes that foundation and adds property attributes, risk scoring, valuations, and environmental data on top.
This comparison explains where each provider sits, what they deliver, and why many buyers will use both.
Who is Ordnance Survey?
Ordnance Survey is Britain's national mapping agency, established in 1791 and now operating as a government-owned company. It maintains the definitive geospatial record of Great Britain, including the master address database (AddressBase), topographic mapping (OS MasterMap), terrain models, and the national grid reference system.
For developers and businesses, the primary access point is the OS Data Hub, which provides APIs for address lookup (OS Places API), mapping (OS Maps API), feature data (OS Features API), and linked identifiers. The OS Places API draws on AddressBase Premium, which contains every known address in Great Britain along with its UPRN, classification, geolocation, and lifecycle status.
OS Data Hub offers a free tier worth up to £1,000 per month in API transactions, which is generous enough for development and low-volume production use. Beyond that, pricing moves to a premium plan with per-transaction charges. Licensing for larger volumes or offline use of datasets like AddressBase requires a commercial licence agreement, typically negotiated with the OS sales team.
Ordnance Survey's data is the authoritative source for geographic coordinates, address matching, and property classification in the UK. Over 90% of UK address lookup services, including Chimnie's own, use OS or PAF data as their starting point.
PropertyData property market analytics website screenshot
Who is Chimnie?
Chimnie was founded by Jon Francis, formerly of Google's innovation team, to make UK property data more accessible. The company operates chimnie.com as a B2B property data bureau for insurers, lenders, and proptech firms, alongside chimnie.co.uk, a free consumer research site with over 150,000 users.
Chimnie integrates Ordnance Survey data - including UPRN-based addressing and geospatial referencing - as part of its data infrastructure. On top of this foundation, Chimnie adds over 500 property attributes per address, spanning EPC data, flood risk, subsidence, conservation areas, listed buildings, rebuild cost estimates, automated valuations, planning permissions, and structural characteristics.
Pricing is published: residential lookups from £0.05 to £0.15 per property, commercial at £0.45, with volume discounts via ratecard.
What OS provides versus what Chimnie adds
The distinction is straightforward. OS provides the "where" - accurate coordinates, validated addresses, property classifications, boundary data, and topographic context. Chimnie provides the "what" - what the property is like, what risks it faces, what it's worth, what's been built or modified, and what environmental factors affect it.
Address lookup and geocoding
OS Places API is the gold standard for UK address lookup. It supports postcode search, UPRN lookup, partial address matching, and radius-based geosearch. Results include the full AddressBase Premium record with classification codes, coordinates, and lifecycle status.
Chimnie offers address autocomplete and UPRN-based lookup through its own API, built on top of OS and PAF data. The difference is what comes back with the address. An OS Places call returns the address record and its location. A Chimnie call returns the address plus 500+ property attributes, risk scores, valuations, and environmental data in a single response.
Mapping and geospatial data
Ordnance Survey's mapping products are unmatched in the UK. OS Maps API provides detailed topographic mapping at multiple scales, OS Features API gives access to individual geographic features from OS MasterMap, and OS NGD (National Geographic Database) is the next-generation integrated dataset. For any application that needs to display maps, calculate distances, or work with land parcels and boundaries, OS is the source.
Chimnie does not provide mapping or topographic data. It uses OS geospatial references internally but does not expose mapping services through its API. If you need to display a map or work with land boundaries, you need OS directly.
Property characteristics and risk
This is where Chimnie adds value that OS does not attempt to provide. OS data tells you a property exists at a specific location with a specific classification. Chimnie tells you its energy rating, flood risk level, subsidence exposure, whether it's listed, whether it's in a conservation area, its estimated rebuild cost, its automated valuation, its roof condition, whether it has solar panels, and what planning permissions have been applied for or granted.
OS does carry some property-adjacent information in AddressBase - the classification codes distinguish residential from commercial, and there are flags for properties under construction or demolished. But attribute-level property intelligence - the kind that feeds insurance pricing, lending decisions, and risk models - is not what OS is built to deliver.
Planning permission data
Chimnie has been completing a two-year national ingestion of planning permission records from every UK local authority, standardised into a consistent schema. This dataset is launching imminently. OS provides some planning-related data through its partnership with the Planning Data platform (planning.data.gov.uk), but this covers policy designations and boundaries rather than individual planning application records.
Pricing comparison
OS Data Hub's free tier (up to £1,000/month in transactions) is excellent for development and testing. Beyond that, OS Places API transactions are priced per call, with costs that vary by volume and licence type. For large-scale commercial use, AddressBase Premium is licensed through annual agreements that can run to tens of thousands of pounds depending on volume and use case.
Chimnie's pricing is simpler and cheaper per lookup for property-enriched data. A premium residential lookup at £0.15 returns the address plus all 500+ attributes, valuations, risk scores, and environmental data. Doing the equivalent by combining OS Places (for the address) with separate providers for EPC, flood, subsidence, AVM, rebuild costs, and planning data would cost significantly more per property and require multiple integrations.
Where OS is essential
OS data is the foundation. You cannot build a serious UK property or address product without it. The coordinate accuracy, address authority, and classification system that OS maintains are used by every serious player in the market, including Chimnie.
For applications that are primarily about geography - mapping, routing, spatial analysis, land parcel identification, emergency services location - OS products are irreplaceable. No other provider in the UK can match the accuracy and completeness of OS geospatial data.
OS also provides data that Chimnie does not: topographic features, terrain models, road networks, points of interest, and boundary data at the land parcel level. If your application needs to know the shape of a property's boundary, the gradient of the land, or the distance to the nearest road junction, OS is where that data lives.
Where Chimnie adds value on top
For any use case that goes beyond "where is this property?" to "what is this property like?", Chimnie picks up where OS leaves off. Insurance underwriting, mortgage risk assessment, property valuation, portfolio analysis, and planning intelligence all require property-level attributes that OS does not provide.
The free AVM, rebuild cost estimates, EPC data, flood and subsidence scoring, satellite-derived roof analysis, and planning permission records are all products that sit on top of OS addressing data rather than competing with it.
Chimnie's value proposition for most buyers is that it bundles the address resolution (using OS and PAF data under the hood) with the property intelligence layer in a single API call. Instead of querying OS for the address, then a flood provider for risk, then an EPC database for energy data, then a valuation provider for an AVM, Chimnie returns everything in one response.
The consumer platform at chimnie.co.uk also provides a data quality feedback loop. Over 150,000 homeowners checking their own property data and flagging inaccuracies creates ground-truth validation that improves the dataset in ways that purely algorithmic approaches miss.
Chimnie website homepage screenshot
Who should choose which
If you need mapping, boundary data, topographic features, or authoritative address matching as the core of your product, start with Ordnance Survey. There's no substitute for OS geospatial data in the UK.
If you need property intelligence - attributes, risk scores, valuations, rebuild costs, planning data - for insurance, lending, or property analytics, Chimnie delivers that in a single API with transparent pricing. Chimnie already integrates OS data as part of its infrastructure, so you get the addressing foundation included.
For most property data buyers, the question isn't Chimnie or OS - it's whether you need to access OS data directly (for mapping and spatial analysis) in addition to Chimnie's property intelligence API. The two are complementary layers of the same stack, and Chimnie's partnership with OS reflects exactly that relationship.
Conclusion
Ordnance Survey provides the geospatial foundation of UK property data - addresses, coordinates, classifications, mapping, and boundaries. Chimnie builds the property intelligence layer on top - attributes, risk, valuations, rebuild costs, and planning data. They are partners, not competitors, and most serious property data operations will use elements of both. The choice is about which layer your use case primarily sits in, and whether you need direct OS access or whether Chimnie's integrated API gives you the addressing foundation alongside the property intelligence you actually need.
