JSON has a simple spec. Learn it.

The spec has some useful terminology. Objects have pairs and Arrays have elements.

1. Key Names

   • Know the different word separation styles. Common ones include lowerCamelCase, snake_case, dash-case, and UpperCamelCase.
   • lowerCamelCase is a good choice, since it's the default in JavaScript, and other popular client-side languages, like Android and Objective C. It's better to have server-side developers handle differences in word separation styles than to leave that job up to client-side developers.
   • Don't mix different word separation styles in the same document. If you are working on an existing application and want to change the word separation style, change it quickly or not at all.
   • If you need to use json keys in urls and xml tags and attribute names, find a library that converts from lowerCamelCase to dash-case, and from dash-case to lowerCamelCase. If you do this a lot, consider using dash-case.
   • Use the same id key across an application (id and _id are popular choices for key names)

2. Extra Types

   • JSON comes with a few simple types. Often applications need other types, like dates and symbols. It's also useful to note
   • Types for the most part should be contextually defined. If you need to store values of two different types, consider using different key names.
   • When you need to have a mix of things of different types, have a clear and obvious way of differentiating between types.
   • If the rules for types are complex, specify the types explicitly in the JSON, by wrapping values in objects, and using a pair to specify the type. For instance, if you had an array with dollars and pounds as strings, you might convert them from ["£8", "$15"] to [{"type": "pounds", "value": 8}, {"type": "dollars", value: 15}].

3. Dates

   • Use ISO dates or UNIX timestamps for dates
   • Avoid unusual formats like the ASP.net AJAX format.

4. Sets

   • A set is like a JSON object (also called a hash) but with no values; only the keys.
   • There is no set type in JSON.
   • Arrays and objects are commonly used as sets. Be consistent in which you use. If you use objects, be consistent in what you use for the values.
   • If you're building an API and want it to be quick to read, a list may be the most intuitive. An example is tags for a blog post. ["programming", "json"] reads easier than {"programming": true, "json": true}.
   • The object is more efficient when you're actually doing something with a set, but sometimes sets are moved around unmodified. For this a list will be more efficient.

5. Complex Types

   • A complex type is something like a location (latitude and longitude) or a link (text and url) that might take up two pairs in an object.

• JSON validator
• JSON Schema