My flat wouldn't sell. So I built a tool to find out why — and the data was brutal

Sharing my experience selling my flat. Listed for nearly two years since September 2024 — two agents, very few viewings, and a painful series of price reductions from above £900k all the way down to £750k.

After the second agent went quiet, I started doing my own research on Zoopla and Rightmove. What struck me was how fragmented everything was. There was no single place to see a simple sold price trend at street or postcode level. No clear picture of what properties actually sold for over the years.

So I vibe-coded a site. It pulls sold prices from the HM Land Registry and aggregates them by postcode — giving a clear view of YoY change and 3-year rolling average prices for that exact area with sold volume each year.

What I found was a reality check. Sales in my block were strong in 2022–23, with 12 and 14 transactions respectively. I should have listed when we moved out in 2021. Instead, I overestimated the market — and I'm now selling at the 2025 median price. Offer agreed at £715k.

Onwards, planning to use this site to find the right street/area to buy for investment.

Here's where I think it could be useful, (happy to share the link in comments if anyone's interested, it's relatively new - google takes time to index)

• Sellers — benchmark your asking price against actual sold data, not estimates. Know when to accept an offer.
• Buyers/ Investors — narrow your search before diving into listings. Especially useful if you're not local and want to shortlist areas by price trend and volume. also know what a fair offer looks like.
• Agents (interesting insight I learnt recently) — could use the data to have honest conversations with vendors about realistic pricing and when to move.

Cross-reference with Rightmove and Zoopla as always — but this gives you a grounded starting point.

Would love any feedback, and to hear what data points you'd find useful.