摘自:Arnaud Lauret的书《Web api的设计》。”:

JSON数据格式

JSON是一种基于JavaScript编程语言描述数据的文本数据格式，尽管它的名字是JSON，但它完全独立于语言(参见https://www.json.org/)。使用JSON，可以描述包含无序名称/值对的对象，也可以描述包含有序值的数组或列表，如图所示。

An object is delimited by curly braces ({}). A name is a quoted string ("name") and is sep- arated from its value by a colon (:). A value can be a string like "value", a number like 1.23, a Boolean (true or false), the null value null, an object, or an array. An array is delimited by brackets ([]), and its values are separated by commas (,). The JSON format is easily parsed using any programming language. It is also relatively easy to read and write. It is widely adopted for many uses such as databases, configura- tion files, and, of course, APIs.

YAML

YAML (YAML Ain 't Markup Language)是一种人性化的数据序列化格式。和JSON一样，YAML (http://yaml.org)也是一种键/值数据格式。该图显示了两者的比较。

注意以下几点:

在YAML中，属性名和值周围没有双引号(“”)。 JSON的结构花括号({})和逗号(，)被换行符和取代 YAML的压痕。 数组中的括号([])和逗号(，)被破折号(-)和换行符取代 YAML。 与JSON不同，YAML允许以#开头的注释。 将其中一种格式转换为另一种格式相对容易。不过要预先警告，在将YAML文档转换为JSON时会丢失注释。

绕过深奥的理论

这回答了标题，而不是细节，因为大多数人只是从谷歌上的搜索结果中阅读标题，就像我一样，所以我觉得有必要从web开发人员的角度解释。

YAML uses space indentation, which is familiar territory for Python developers. JavaScript developers love JSON because it is a subset of JavaScript and can be directly interpreted and written inside JavaScript, along with using a shorthand way to declare JSON, requiring no double quotes in keys when using typical variable names without spaces. There are a plethora of parsers that work very well in all languages for both YAML and JSON. YAML's space format can be much easier to look at in many cases because the formatting requires a more human-readable approach. YAML's form while being more compact and easier to look at can be deceptively difficult to hand edit if you don't have space formatting visible in your editor. Tabs are not spaces so that further confuses if you don't have an editor to interpret your keystrokes into spaces. JSON is much faster to serialize and deserialize because of significantly less features than YAML to check for, which enables smaller and lighter code to process JSON. A common misconception is that YAML needs less punctuation and is more compact than JSON but this is completely false. Whitespace is invisible so it seems like there are less characters, but if you count the actual whitespace which is necessary to be there for YAML to be interpreted properly along with proper indentation, you will find YAML actually requires more characters than JSON. JSON doesn't use whitespace to represent hierarchy or grouping and can be easily flattened with unnecessary whitespace removed for more compact transport.

房间里的大象:互联网本身

JavaScript显然以巨大的优势统治着网络，JavaScript开发人员更喜欢使用JSON作为数据格式，以及流行的web api，因此在进行一般意义上的web编程时，很难争论使用YAML还是JSON，因为在团队环境中你可能会被压倒。事实上，大多数web程序员甚至不知道YAML的存在，更不用说考虑使用它了。

如果你正在做任何web编程，JSON是默认的方式，因为使用JavaScript时不需要翻译步骤，所以在这种情况下，你必须提出一个更好的参数来使用YAML而不是JSON。

有时候你不需要在两者之间做出选择。

例如，在围棋中，你可以同时拥有这两者:

type Person struct {
    Name string `json:"name" yaml:"name"`
    Age int `json:"age" yaml:"age"`
}

由于这个问题现在在搜索YAML和JSON时非常突出，值得注意的是两者之间一个很少被引用的区别:许可证。JSON声称拥有一个JSON用户必须遵守的许可(包括法律上模棱两可的“应使用代表善，而不是恶”)。YAML没有这样的许可声明，这可能是一个重要的区别(对您的律师来说，如果不是对您来说)。

差异:

YAML, depending on how you use it, can be more readable than JSON JSON is often faster and is probably still interoperable with more systems It's possible to write a "good enough" JSON parser very quickly Duplicate keys, which are potentially valid JSON, are definitely invalid YAML. YAML has a ton of features, including comments and relational anchors. YAML syntax is accordingly quite complex, and can be hard to understand. It is possible to write recursive structures in yaml: {a: &b [*b]}, which will loop infinitely in some converters. Even with circular detection, a "yaml bomb" is still possible (see xml bomb). Because there are no references, it is impossible to serialize complex structures with object references in JSON. YAML serialization can therefore be more efficient. In some coding environments, the use of YAML can allow an attacker to execute arbitrary code.

观察:

Python programmers are generally big fans of YAML, because of the use of indentation, rather than bracketed syntax, to indicate levels. Many programmers consider the attachment of "meaning" to indentation a poor choice. If the data format will be leaving an application's environment, parsed within a UI, or sent in a messaging layer, JSON might be a better choice. YAML can be used, directly, for complex tasks like grammar definitions, and is often a better choice than inventing a new language.

JSON编码六种数据类型:对象(映射)、数组、字符串数字、布尔值和Null。对于机器来说，它非常容易解析，并且提供很少的灵活性。说明书大约有一页半。

YAML allows the encoding of arbitrary Python data and other crazy crap (which leads to vulnerabilities when decoding it). It is hard to parse because it offers so much flexibility. The specification for YAML was 86 pages, the last time I checked. YAML syntax is obviously influenced by Python, but maybe they should have been a little more influenced by the Python philosophy on a few points: e.g. “there should be one—and preferably only one—obvious way to do it” and “simple is better than complex.”

与JSON相比，YAML的主要优点是更容易阅读和编辑，这使它成为配置文件的自然选择。

最近，我倾向于使用TOML作为配置文件。它不像YAML那样漂亮或灵活，但对机器和人类来说都更容易解析。该语法(几乎)是INI语法的超集，但它解析为类似json的数据结构，只添加了一种额外类型:日期类型。