> For the complete documentation index, see [llms.txt](https://docs.fluentd.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fluentd.org/formatter.md).

# Formatter Plugins

Fluentd has nine (9) types of plugins:

* [Input](/input.md)
* [Parser](/parser.md)
* [Filter](/filter.md)
* [Output](/output.md)
* [Formatter](/formatter.md)
* [Storage](/storage.md)
* [Service Discovery](/service_discovery.md)
* [Buffer](/buffer.md)
* [Metrics](/metrics.md)

This article gives an overview of the Formatter Plugin.

## Overview

Sometimes, the output format for an output plugin does not meet one's needs. Fluentd has a pluggable system called Formatter that lets the user extend and reuse custom output formats.

## How To Use

For an output plugin that supports Formatter, the `<format>` directive can be used to change the output format.

For example, by default, [`out_file`](/output/file.md) plugin outputs data as

```
2014-08-25 00:00:00 +0000<TAB>foo.bar<TAB>{"k1":"v1", "k2":"v2"}
```

However, if you set `@type json` in `<format>` like this:

```
<match foo.bar>
  @type file
  path /path/to/file
  <format>
    @type json
  </format>
</match>
```

The output changes to

```javascript
{"k1":"v1", "k2":"v2"}
```

i.e., each line is a single JSON object without "time" and "tag" fields. If you want to include "time" and "tag", use [Inject section](/configuration/inject-section.md).

See [this section](/plugin-development.md#text-formatter-plugins) to learn how to develop a custom formatter.

## List of Built-in Formatters

* [`out_file`](/formatter/out_file.md)
* [`json`](/formatter/json.md)
* [`ltsv`](/formatter/ltsv.md)
* [`csv`](/formatter/csv.md)
* [`msgpack`](/formatter/msgpack.md)
* [`hash`](/formatter/hash.md)
* [`single_value`](/formatter/single_value.md)
* [`tsv`](/formatter/tsv.md)

## List of Output/Filter Plugins with Formatter Support

* [`filter_stdout`](/filter/stdout.md)
* [`out_file`](/output/file.md)
* [`out_s3`](/output/s3.md)

If this article is incorrect or outdated, or omits critical information, please [let us know](https://github.com/fluent/fluentd-docs-gitbook/issues?state=open). [Fluentd](http://www.fluentd.org/) is an open-source project under [Cloud Native Computing Foundation (CNCF)](https://cncf.io/). All components are available under the Apache 2 License.