> 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-maps-api/technical-specification.md).

# Technical specification

This technical specification explains the content of the OS Maps API, and the methods that you can use to call it. If you are not familiar with the OS Maps API you may want to read the getting started guide before proceeding.

{% hint style="info" %}
If you are not familiar with the OS Maps API, please read the [overview documentation ](/os-apis/accessing-os-apis/os-maps-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 Maps API is available using the Open Geospatial Consortium Web Map Tile Service (OGC WMTS) standard and as ZXY.

<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>WMTS</strong></td><td>Access raster tiles in a WMTS format.</td><td><a href="/os-apis/accessing-os-apis/os-maps-api/technical-specification/wmts.md">WMTS</a></td></tr><tr><td><strong>ZXY</strong></td><td>Access raster tiles in a ZXY format.</td><td><a href="/os-apis/accessing-os-apis/os-maps-api/technical-specification/zxy.md">ZXY</a></td></tr></tbody></table>


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