# Building an optimized site

Material for MkDocs, by default, allows to build optimized sites that rank great
on search engines, load fast (even on slow networks), and work perfectly without
JavaScript. Additionally, the [built-in optimize plugin] adds support for
further useful automatic optimization techniques.

  [built-in optimize plugin]: #built-in-optimize-plugin

## Configuration

### Built-in optimize plugin :material-alert-decagram:{ .mdx-pulse title="Added on January 21, 2023" }

[:octicons-heart-fill-24:{ .mdx-heart } Sponsors only][Insiders]{ .mdx-insiders } ·
[:octicons-tag-24: insiders-4.29.0][Insiders] ·
:octicons-cpu-24: Plugin ·
:octicons-beaker-24: Experimental

The built-in optimize plugin automatically identifies and optimizes all media
files as part of the build using compression and conversion techniques. Add
the following lines to `mkdocs.yml`:

``` yaml
plugins:
  - optimize # (1)!
```

1.  Please ensure that all [dependencies for image processing] are installed,
    or the plugin will not work properly.

> If you need to be able to build your documentation with and without
> [Insiders], please refer to the [built-in plugins] section to learn how
> shared configurations help to achieve this.

The following configuration options are available:

[`enabled`](#+optimize.enabled){ #+optimize.enabled }

:   :octicons-milestone-24: Default: `true` – This option specifies whether
    the plugin is enabled when building your project. If you want to speed up
    local builds, you can use an [environment variable]:

    ``` yaml
    plugins:
      - optimize:
          enabled: !ENV [CI, false]
    ```

[`concurrency`](#+optimize.concurrency){ #+optimize.concurrency }

:   :octicons-milestone-24: Default: _number of CPUs_ – This option specifies
    how many CPUs the plugin is allowed to use when optimizing media files.
    With more CPUs, the plugin can do more work in the same time, thus complete
    optimization faster. Concurrent processing can be disabled with:

    ``` yaml
    plugins:
      - optimize:
          concurrency: 1
    ```

#### Optimization

Technical documentation often includes screenshots or diagrams, both of which
are prime candidates for compression. The [built-in optimize plugin] allows to
automatically compress images using [pngquant] (for PNGs), and [Pillow]
(for JPGs).

The following configuration options are available for optimization:

[`optimize_png`](#+optimize.optimize_png){ #+optimize.optimize_png }

:   :octicons-milestone-24: Default: `true` – This option specifies whether
    the plugin should optimize PNG files using [pngquant], which must be
    installed on the system. PNG optimization can be disabled with:

    ``` yaml
    plugins:
      - optimize:
          optimize_png: false
    ```

[`optimize_png_speed`](#+optimize.optimize_png_speed){ #+optimize.optimize_png_speed }

:   :octicons-milestone-24: Default: `4` of `[1,10]` – This option specifies the
    speed/quality tradeoff that [pngquant] applies when compressing. The lower
    the number, the more time will be spent optimizing:

    === "Slower <small>small</small>"

        ``` yaml
        plugins:
          - optimize:
              optimize_png_speed: 1
        ```

    === "Faster <small>rough</small>"

        ``` yaml
        plugins:
          - optimize:
              optimize_png_speed: 10
        ```

    A factor of `10` has 5% lower quality, but is 8x faster than the default `4`.

[`optimize_png_strip`](#+optimize.optimize_png_strip){ #+optimize.optimize_png_strip }

:   :octicons-milestone-24: Default: `true` – This option specifies whether
    [pngquant] should remove all non-optional metadata that is not necessary
    for rendering images in a browser:

    ``` yaml
    plugins:
      - optimize:
          optimize_png_strip: false
    ```

[`optimize_jpg`](#+optimize.optimize_jpg){ #+optimize.optimize_jpg }

:   :octicons-milestone-24: Default: `true` – This option specifies whether
    the plugin should optimize JPG files using [Pillow], a Python image
    processing library. JPG optimization can be disabled with:

    ``` yaml
    plugins:
      - optimize:
          optimize_jpg: false
    ```

[`optimize_jpg_quality`](#+optimize.optimize_jpg_quality){ #+optimize.optimize_jpg_quality }

:   :octicons-milestone-24: Default: `60` of `[0,100]` – This option specifies
    the image quality that [Pillow] uses when compressing. If the images look
    blurry, it's a good idea to tune and change this setting:

    ``` yaml
    plugins:
      - optimize:
          optimize_jpg_quality: 75
    ```

[`optimize_jpg_progressive`](#+optimize.optimize_jpg_progressive){ #+optimize.optimize_jpg_progressive }

:   :octicons-milestone-24: Default: `true` – This option specifies whether
    [Pillow] should use [progressive encoding] (faster rendering) when
    compressing JPGs. Progressive encoding can be disabled with:

    ``` yaml
    plugins:
      - optimize:
          optimize_jpg_progressive: false
    ```

  [Insiders]: ../insiders/index.md
  [built-in plugins]: ../insiders/getting-started.md#built-in-plugins
  [dependencies for image processing]: dependencies/image-processing.md
  [environment variable]: https://www.mkdocs.org/user-guide/configuration/#environment-variables
  [pngquant]: https://pngquant.org/
  [Pillow]: https://pillow.readthedocs.io/
  [progressive encoding]: https://medium.com/hd-pro/jpeg-formats-progressive-vs-baseline-73b3938c2339

#### Caching

The [built-in optimize plugin] implements an intelligent caching mechanism,
ensuring that media files are only pushed through the optimization pipeline when
their contents change. If you swap out or update an image, the plugin will
detect it and update the optimized version.

The following configuration options are available for caching:

[`cache`](#+optimize.cache){ #+optimize.cache }

:   :octicons-milestone-24: Default: `true` – This option specifies whether
    the plugin queries its cache for an existing artifact before starting an
    optimization job. It's normally not necessary to change this setting,
    except for when debugging the plugin itself. Caching can be disabled with:

    ``` yaml
    plugins:
      - optimize:
          cache: false
    ```

[`cache_dir`](#+optimize.cache_dir){ #+optimize.cache_dir }

:   :octicons-milestone-24: Default: `.cache/plugins/optimize` – This option
    specifies the file system location of the plugin's cache. It's normally not
    necessary to change this setting, except for when debugging the plugin
    itself. The cache directory can be changed with:

    ``` yaml
    plugins:
      - optimize:
          cache_dir: .cache/plugins/optimize
    ```

    By default, all built-in plugins that implement caching will create a
    `.cache` directory in the same folder your `mkdocs.yml` resides, and create
    subfolders to not interfere with each other. If you use multiple instances
    of this plugin, it could be necessary to change this setting.