H3 density
GET /v1/h3/density/{area_id}Hex-binned stock and transaction density for map layers, at H3 resolution 8.
Same call over MCP
Hex-binned density for mapsh3_densityAuthenticate with an API key from the API & MCP Hub. The same call is available as an MCP tool at the same price.
Reference
What GET /v1/h3/density/{area_id} returns
DENSITY ONLY. There is no usable price per cell — the hex cube's price column is populated on about 2% of rows and its rental, EPC and per-m2 columns are empty. The response lists what is and is not available; do not offer a price heatmap from this.
tx_n is the transaction COUNT and tx_value is the total in pounds.
UK only.
Inputs
Before you call it
- area_id
- The area id is the analytics area identifier, not a name or a GSS code. Call area_resolve with a place name or code ("Hackney", "E5") first; it is free and returns the id with the area's hierarchy. Where it gives both
area_idandanalytics_area_id, passanalytics_area_id.
Request
Calling GET /v1/h3/density/{area_id}
curl "https://api.marketcode.ai/v1/h3/density/c0694b59-04d1-48ab-9a4c-c4f9d7b74f60?limit=3" \
-H "Authorization: Bearer $MARKETCODE_API_KEY"Send your API key as a Bearer token. Every response carries credits_charged and credits_remaining.
Inputs
Parameters
| Name | In | Type | Required | Description |
|---|---|---|---|---|
| area_id | Path | string | Yes | Marts area id from /areas/resolve |
| limit | Query | integer | No | Default: 2000 |
Response
What GET /v1/h3/density/{area_id} returns for a real request
curl "https://api.marketcode.ai/v1/h3/density/c0694b59-04d1-48ab-9a4c-c4f9d7b74f60?limit=3" \
-H "Authorization: Bearer $MARKETCODE_API_KEY"{
"area_id": "c0694b59-04d1-48ab-9a4c-c4f9d7b74f60",
"resolution": null,
"cells": [],
"count": 0,
"available": [
"stock_count",
"tx_n",
"tx_value"
],
"not_available": "price per cell — h3_facts.tx_price_median is populated on ~2% of rows and the psm, rental, EPC and AVM columns are empty",
"credits_charged": 0
}A real response, captured from production and trimmed: arrays to three items, long strings shortened, volatile keys dropped.
Response
Response fields
| Field | Type | Example |
|---|---|---|
| area_id | string | c0694b59-04d1-48ab-9a4c-c4f9d7b74f60 |
| resolution | null | |
| cells | array | |
| count | integer | 0 |
| available | array | |
| not_available | string | price per cell — h3_facts.tx_price_median is pop |
| credits_charged | integer | 0 |
Fields observed in the example response above; a field the example did not exercise is not listed.
Price and licence
What it costs, and where the data comes from
H3 density is free over MCP and over REST, and the two surfaces share one credit balance. Free calls need a signed-in account or an API key and appear in your usage, but they never touch your balance.
Credits are granted on sign-up and bought in packs; the pricing page lists every call.
Sources
- HM Land Registry
Price Paid Data
Open Government Licence v3 · England and Wales
- Ordnance Survey
National Geographic Database (buildings, land and sites)
Used under licence from Ordnance Survey · Great Britain
Related
Endpoints used with H3 density
- Built-stock profile of an areaFree
area_stock_profileComposition of the built stock in an area: unit counts, HMO share, mixed-use share, median building height and footprint, solar penetration.Same category - Physical form of buildings3 credits
building_physicalPhysical form of the buildings a set of UPRNs sit in: height, volume, footprint area, floor count, construction and roof material, basement, green roof, solar panels, and the residential/commercial unit mix.Same category - Mixed-use buildings in an area6 credits
mixed_use_buildingsBuildings holding BOTH residential and commercial units — the conversion and permitted-development cohort.Same category - Plot utilisation of land parcels6 credits
plot_utilisationLand parcels by size and how much of them is built on. Set `max_built_coverage` to 0.2 to find largely undeveloped plots.Same category
FAQ
Questions about H3 density
How much does `h3_density` cost?
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H3 density is free over MCP and over REST, and the two surfaces share one credit balance. Free calls need a signed-in account or an API key and appear in your usage, but they never touch your balance.
Where do I get the area id?
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From area_resolve, which is free: give it a place name or postcode district and it returns the area id, centroid and hierarchy. h3_density then takes that id.
How do I authenticate?
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Send your API key as a Bearer token in the Authorization header. Keys are created in the API & MCP Hub, shown once and revocable. Every response carries the credits charged and your remaining balance.
Is there an MCP version?
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Yes. The h3_density tool on the MarketCode MCP server is the same call at the same price, signed in with OAuth rather than a key, so Claude, ChatGPT, Codex and Cursor can run it in a conversation.
Where does the data come from?
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Read from HM Land Registry price paid data and Ordnance Survey NGD. Coverage is the UK.
Does `h3_density` change anything?
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No. The tool is annotated read-only on the server, so it never writes to your data or ours and an assistant can call it without a confirmation step.
Try H3 density on a real address.
30-minute call. We'll provision a key and walk through the endpoint on your use case.