> For the complete documentation index, see [llms.txt](https://docs.os.uk/os-apis/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.os.uk/os-apis/accessing-os-apis/os-vector-tile-api/technical-specification.md).

# Technical specification

This technical specification explains the content of the OS Vector Tile API and the methods that you can use to call it.

{% hint style="info" %}
If you are not familiar with the OS Vector Tile API, please read the [overview documentation ](/os-apis/accessing-os-apis/os-vector-tile-api.md)before proceeding.
{% endhint %}

## Core concepts

This specification does not cover core concepts that apply to all Ordnance Survey APIs.

Please read the following pages to learn more about OS API core concepts:

* [Authentication](/os-apis/core-concepts/authentication.md)
* [Error codes](/os-apis/core-concepts/error-codes.md)
* [Rate-limiting policy](/os-apis/core-concepts/rate-limiting-policy.md)

## API reference

OS Vector Tile API is currently available as EPSG:27700 (British National Grid which is applicable just for GB) and EPSG:3857 (Web Mercator which is a global coordinate system). The maps are available as raw information presented using compressed packets of geographic data using the Protocolbuffer Binary Format (.pbf). This provides users optimised maps which render quickly on the web and offer a slick mapping experience.

OS Vector Tile API is currently available as EPSG:27700 (British National Grid which is applicable just for GB) and EPSG:3857 (Web Mercator which is a global coordinate system). The maps are available as raw information presented using compressed packets of geographic data using the Protocolbuffer Binary Format (.pbf). This provides users optimised maps which render quickly on the web and offer a slick mapping experience.

OS Vector Tile API has three main endpoints:

<table data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>Service metadata</strong></td><td>Service metadata for the OS Vector Tiles API.</td><td><a href="/pages/pviAej4x7HbZGjDxCV3Y">/pages/pviAej4x7HbZGjDxCV3Y</a></td></tr><tr><td><strong>Stylesheet</strong></td><td>Discover compatible stylesheet.</td><td><a href="/pages/VxZ1a7w8a61q55b7zEG0">/pages/VxZ1a7w8a61q55b7zEG0</a></td></tr><tr><td><strong>Tile request</strong></td><td>Access vector tiles.</td><td><a href="/pages/MB3AGeG1uxTnBmfKEXcg">/pages/MB3AGeG1uxTnBmfKEXcg</a></td></tr></tbody></table>


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