Chimnie and Ideal Postcodes both offer APIs that return UK address data, but they serve fundamentally different purposes. Ideal Postcodes is a specialist address lookup and validation service built for checkout forms, CRM systems, and any application that needs to capture a clean UK address. Chimnie is a property data platform that includes address lookup but goes far beyond it, returning over 500 attributes per property covering risk, value, planning, and structural characteristics.
This comparison is based on publicly available product and pricing information. It's written for developers, product teams, and data buyers evaluating UK address and property data options.
Who is Ideal Postcodes?
Ideal Postcodes is a UK-based address validation provider that has built a strong reputation among developers for clean documentation, transparent pricing, and reliable service. The company focuses on making address capture simple and accurate, with pre-built integrations for over 30 platforms including Shopify, WooCommerce, Magento, Salesforce, HubSpot, and Gravity Forms.
The core product is a REST API that provides postcode lookup, address autocomplete, and address cleansing. For UK addresses, Ideal Postcodes licenses Royal Mail's Postcode Address File (PAF) and Ordnance Survey AddressBase data, returning formatted addresses with UPRNs and rooftop-level geocodes included at no additional charge. This is a genuine differentiator among address lookup providers, many of whom charge extra for UPRN and coordinate data.
Ideal Postcodes also covers international addresses through partnerships with local postal authorities and HERE data, supporting over 240 countries. Additional services include email validation and phone number validation, making it a broader contact data verification platform rather than just a UK postcode lookup.
Pricing is pay-as-you-go with credit bundles. The smallest bundle is 200 lookups for £9 (£0.045 per lookup), scaling down to around £0.028 per lookup at the 32,100 credit tier (£900). Credits last 12 months from first use, there are no monthly fees, and a free trial gives 50 credits to test with. The pricing is transparent, published on the website, and genuinely competitive for pure address lookup.
The company also maintains postcodes.io, a free open-source UK postcode API that serves ONS Postcode Directory and Ordnance Survey Open Names data. This community contribution has earned Ideal Postcodes goodwill among the developer community.
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 transparent and 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 property research site with over 150,000 users.
Chimnie's REST API covers 35 million UK residential properties and returns over 500 attributes per property. These span EPC data, flood risk, subsidence indicators, conservation areas, listed buildings, rebuild cost estimates, automated valuations, planning permissions, and structural characteristics. The company is completing a two-year ingestion of planning permission data from every UK local authority, launching imminently as the only full national planning dataset from a single provider.
Chimnie offers free address autocomplete as part of its API, with property data lookups priced from £0.05 to £0.15 per residential property on PAYG, and £0.45 for commercial properties. Volume discounts are available through a published ratecard.
Feature comparison
Address lookup and autocomplete
Ideal Postcodes delivers a polished address capture experience. The autocomplete API returns suggestions as users type, with fuzzy matching that handles common typos and abbreviations. Postcode lookup returns all addresses at a given postcode with formatted address lines, coordinates, and UPRNs. The 30+ platform integrations mean many businesses can add address capture without writing code.
Chimnie offers free address autocomplete that returns similar address data, built on the same PAF and OS foundations. The difference isn't in the address capture itself but in what happens next. An Ideal Postcodes call returns the address. A Chimnie call can return the address plus everything known about the property at that address.
For a checkout form or contact form where the goal is simply to capture a clean address quickly, both work. Ideal Postcodes has more pre-built integrations for common e-commerce and CRM platforms. Chimnie's strength is what comes after the address capture.
Property data beyond the address
This is where the comparison diverges. Once you have an address, Ideal Postcodes stops. The data returned is the address itself: formatted lines, postcode, UPRN, coordinates, and classification. There is no information about the property at that address.
Chimnie returns over 500 attributes per property. EPC data including current and potential energy ratings, heating type, wall construction, and insulation. Flood risk from multiple sources. Subsidence exposure. Conservation area and listed building status. Rebuild cost estimates with confidence intervals and finish-quality segmentation. Automated valuations with separate listing and sale price models. Planning permission records. Satellite-derived features including roof condition, solar panel detection, and garden boundaries.
If your application needs to know anything about the property beyond its address, Chimnie provides it. Ideal Postcodes does not attempt to.
International coverage
Ideal Postcodes covers over 240 countries through partnerships with local postal authorities and HERE data. This is a genuine strength for businesses with international customers. Chimnie focuses exclusively on UK properties. If you need global address validation, Ideal Postcodes has broader geographic reach.
Automated valuations
Chimnie provides the UK's only free AVM, with UPRN-based lookups at zero cost. Ideal Postcodes does not offer property valuations.
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 captures extensions, conversions, and changes of use that affect property risk and value. Ideal Postcodes does not cover planning data.
Rebuild cost estimates
Chimnie provides rebuild cost estimates with confidence intervals and regional breakdowns. Ideal Postcodes does not offer this.
Email and phone validation
Ideal Postcodes offers email validation and phone number validation alongside address lookup, making it a broader contact data verification tool. Chimnie does not offer email or phone validation. Its focus is property data, not contact data.
Pricing comparison
Ideal Postcodes pricing for pure address lookup is competitive. At the 200-credit tier, each lookup costs £0.045. At the 32,100-credit tier, it drops to £0.028. Credits last 12 months. The free UPRN and geocode inclusion is a genuine differentiator among address providers.
Chimnie's address autocomplete is free. Property data lookups cost £0.05 to £0.15 per residential property depending on the data tier, and £0.45 for commercial. If you only need addresses, Chimnie's free autocomplete may be all you need.
The comparison gets interesting when your application needs more than just the address. If you need address capture followed by flood risk, EPC data, a valuation, or rebuild costs, using Ideal Postcodes for the address and then sourcing property data from separate providers will cost more per property and require multiple integrations. Chimnie returns everything from one API.
For pure address lookup at scale, Ideal Postcodes is cheaper per lookup and purpose-built for the job. For address lookup plus property intelligence, Chimnie is more cost-effective overall because the address capture is free and the property data comes bundled.
Where Ideal Postcodes is stronger
Ideal Postcodes wins on developer experience for address capture. The documentation is excellent, the 30+ platform integrations cover most common use cases without code, and the API is designed specifically for the address lookup workflow. The fuzzy matching, autocomplete suggestions, and address formatting are polished.
International coverage is a clear advantage. If your business serves customers globally and needs address validation across multiple countries, Ideal Postcodes handles this from a single API. Chimnie is UK-only.
The pricing model for pure address lookup is hard to beat. Pay-as-you-go with 12-month credit validity, no monthly fees, and free UPRNs and geocodes make it one of the most transparent and cost-effective address lookup services in the UK market.
Ideal Postcodes' contribution to the developer community through postcodes.io and its open-source projects is worth noting. The company has built genuine trust among developers through transparency and community engagement.
Email and phone validation as additional services mean businesses can verify multiple types of contact data from one provider, which simplifies vendor management for customer onboarding workflows.
Where Chimnie is stronger
For any use case that goes beyond address capture to property intelligence, Chimnie is the stronger platform. Over 500 property attributes per lookup versus an address record is a different order of magnitude of data.
The free AVM, rebuild cost estimates, planning permission data, flood and subsidence scoring, EPC data, and satellite-derived property characteristics are products that no address lookup provider offers. These are the data feeds that power insurance underwriting, mortgage risk assessment, property analytics, and portfolio enrichment.
Chimnie's free address autocomplete means you get address capture at no cost, with the option to pull property data for the same address in the same API ecosystem. For businesses that need both address capture and property intelligence, this eliminates the need for two separate providers.
The consumer platform at chimnie.co.uk, with over 150,000 users checking their own property data, creates a ground-truth validation loop that improves data quality in ways that address-only providers cannot match.
For property-focused applications, starting with Chimnie means one integration point for both addressing and property data. Starting with Ideal Postcodes for address capture and then adding separate property data providers means multiple integrations, multiple contracts, and higher total cost per property.
Chimnie website homepage screenshot
Who should choose which
E-commerce businesses needing checkout address capture should use Ideal Postcodes. The integrations with Shopify, WooCommerce, and other platforms make it simple, and you don't need property data for a checkout form.
CRM and contact management systems where the goal is clean address and contact data will find Ideal Postcodes more suitable, especially with the added email and phone validation.
Businesses with international customers needing global address validation should use Ideal Postcodes for its multi-country coverage.
Insurance platforms should choose Chimnie. Address autocomplete gets you started at no cost, and property risk data, rebuild estimates, and valuations are all available from the same integration.
Mortgage and lending platforms need Chimnie. Address capture followed by automated valuation and property risk assessment from one provider reduces both cost and complexity.
Proptech firms and property analytics teams building property-focused products will find more value in Chimnie's depth. One integration for addresses and 500+ property attributes beats stitching together an address provider and multiple data suppliers.
For some businesses, using both makes practical sense. Ideal Postcodes for international address validation on customer-facing forms, Chimnie for UK property intelligence in back-end workflows. The two serve different purposes and complement each other well.
Conclusion
Ideal Postcodes is an excellent address lookup and validation service with transparent pricing, strong developer tools, and broad international coverage. Chimnie is a property data platform where address lookup is the entry point to over 500 property attributes, valuations, risk scores, and planning data.
For pure address capture, Ideal Postcodes is purpose-built and hard to fault. For any application where the address is a starting point for understanding the property itself, Chimnie delivers the depth that address lookup providers were never designed to offer. The choice depends on whether your application stops at the address or needs to know what's behind the front door.
