
Ideal postcodes
Fetchify
Loqate
Data8 UK
Data8 UK PredictiveAddress
Email Verification API
Google Maps API
Fast UK address, email & phone validation APIs for developers. Official Royal Mail PAF data. Pay as you go, 100 free lookups.

StackSource
AI-native commercial mortgage brokerage. One submission, lender matching, and human support through closing. No upfront fees.

Which is more popular?
Website, pricing, platforms and company facts side by side.
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| Website | postio.co.uk | yieldstack.ai |
| Pricing | ||
| Platforms | — | |
| Company | Startup from the United Kingdom · 1 - 9 employees | Startup from the United States · 1 - 9 employees · 2025 |
| Listed in |
In their own words, as submitted to SaaSHub.


Postio (postio.co.uk) is a developer-focused data validation platform providing real-time UK address lookup, email verification, and phone validation via plain REST APIs and drop-in SDKs. As an official Royal Mail PAF Solutions Provider, Postio synchronises 30M+ UK addresses daily for accurate...
YieldStack helps real estate investors, developers, and brokers find commercial mortgage financing from third-party lenders. Borrowers submit a financing request through one platform. AI supports deal preparation and lender-program matching, while YieldStack’s brokerage team helps compare offers,...
What each product offers, as listed by its team.


An editorial look at what each product does well and who it suits.


No analysis of Postio.co.uk yet.
Overall verdict
Why this product is good
Recommended for
How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing Postio.co.uk and YieldStack.
Postio.co.uk's answer
Serving a huge range of customers across the world looking for a blazing fast UK Address AIP product. From bootsrapped entrepreuners to FTSE 250 companies. We serve them all.
YieldStack's answer:
The largest CRE Lenders in the USA
Postio.co.uk's answer
A REST API served from edge locations, with official SDKs for JavaScript/Node, Python, Go, PHP, Ruby and .NET, all open source on GitHub. The API is documented by a public OpenAPI specification.
YieldStack's answer:
AI integrations supporting the platform’s workflows.
Postio.co.uk's answer
Postio charges only when a lookup returns a result — searching is free. Address, email and phone validation sit behind one API with a single JSON response envelope, so you integrate once rather than stitching three vendors together. Address data comes from Royal Mail's Postcode Address File under a direct licence, not scraped or resold sources. There are no tiers, contracts or minimum spend, and the first 100 lookups need no card.
YieldStack's answer:
YieldStack combines AI-assisted lender matching with hands-on commercial mortgage brokerage. Borrowers submit once, compare financing options, and work with a team that handles structuring, negotiation, and closing coordination. Borrowers approve lender outreach, with no upfront fees and a broker fee paid only at closing.
Postio.co.uk's answer
Pricing is published and pay-as-you-go: 2.2p per address, 1p per email, 1p per phone, billed only on a result. No sales call, no annual contract, no minimum commitment. You can be live in a few minutes with 100 free lookups and no card, and the same API covers all three validation types. For UK addresses specifically, the data is licensed directly from Royal Mail rather than obtained second-hand — which matters after the 2025 High Court ruling on database rights in this market.
YieldStack's answer:
YieldStack helps borrowers evaluate the whole financing offer: rate, leverage, fees, reserves, prepayment terms, and closing requirements. Its platform organizes the process, while its brokerage team helps borrowers find suitable lenders and move the deal forward. One submission gives borrowers a coordinated financing process without an upfront brokerage fee.
Postio.co.uk's answer
Developers and technical teams building UK-facing forms — ecommerce checkouts, signup flows, CRM and logistics systems. Typically small to mid-sized product teams, agencies building for UK clients, and software vendors embedding address lookup in their own product. It suits anyone who wants a UK-accurate API without an enterprise procurement process.
YieldStack's answer:
Commercial real estate investors, developers, operators, and mortgage brokers seeking bridge, DSCR, fix-and-flip, construction, multifamily, and permanent financing across the United States.
Postio.co.uk's answer
Postio is a trading name of Onno Group Limited, registered in England & Wales (company no. 08622799). It was built to make Royal Mail PAF-accurate UK validation available on straightforward pay-as-you-go pricing, rather than the contracts and minimum commitments that have been standard in this market. Address, email and phone validation were brought together behind one consistent API so a team can solve all three at once.
YieldStack's answer:
Rommin Adl and Daniel Chesney founded YieldStack to simplify commercial real estate financing. The platform brings deal preparation, lender matching, offer comparison, and closing coordination into one workflow, combining AI-assisted analysis with human brokerage expertise.
Share your experience with using Postio.co.uk and YieldStack. For example, how are they different and which one is better?
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