What is the difference between YAML and JSON?

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What are the differences between YAML and JSON, specifically considering the following things?

  • Performance (encode/decode time)
  • Memory consumption
  • Expression clarity
  • Library availability, ease of use (I prefer C)

I was planning to use one of these two in our embedded system to store configure files.

Related:

Should I use YAML or JSON to store my Perl data?

yaml json
14 Answers

Benchmark results

Below are the results of a benchmark to compare YAML vs JSON loading times, on Python and Perl

JSON is much faster, at the expense of some readability, and features such as comments

Test method

Results

Python 3.8.3 timeit
    JSON:            0.108
    YAML CLoader:    3.684
    YAML:           29.763

Perl 5.26.2 Benchmark::cmpthese
    JSON XS:         0.107
    YAML XS:         0.574
    YAML Syck:       1.050

Perl 5.26.2 Dumbbench (Brian D Foy, excludes outliers)
    JSON XS:         0.102
    YAML XS:         0.514
    YAML Syck:       1.027
user_2519470

From: Arnaud Lauret Book “The Design of Web APIs.” :

The JSON data format

JSON is a text data format based on how the JavaScript programming language describes data but is, despite its name, completely language-independent (see https://www.json.org/). Using JSON, you can describe objects containing unordered name/value pairs and also arrays or lists containing ordered values, as shown in this figure.

enter image description here

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) is a human-friendly, data serialization format. Like JSON, YAML (http://yaml.org) is a key/value data format. The figure shows a comparison of the two.

enter image description here

Note the following points:

  • There are no double quotes (" ") around property names and values in YAML.

  • JSON’s structural curly braces ({}) and commas (,) are replaced by newlines and indentation in YAML.

  • Array brackets ([]) and commas (,) are replaced by dashes (-) and newlines in YAML.

  • Unlike JSON, YAML allows comments beginning with a hash mark (#). It is relatively easy to convert one of those formats into the other. Be forewarned though, you will lose comments when converting a YAML document to JSON.

user_85849040

If you are concerned about better parsing speed then storing the data in JSON is the option. I had to parse the data from a location where the file was subject to modification from other users and hence I used YAML as it provides better readability compared to JSON. And you can also add comments in the YAML file which can't be done in a JSON file.

user_129241140
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