edckwt

This plugin enables you to fetch the contents of your site in JSON format by REST API 
Such as sections, articles and search results 
and return it as json 
To be able to use it in your applications or other sites
Endpoints
<ol>
<li>recent posts</li>
<li>posts</li>
<li>search</li>
<li>categories</li>
<li>category</li>
</ol>
For develpoers
<ul>
<li>/api/get_category_posts?type={string}&slug={string}&id={int}&count={int}&page={int}</li>
<li>/api/get_category_index</li>
<li>/api/get_search_results?type={string}&count={int}&page={int}</li>
<li>/api/get_recent_posts?type={string}</li>
<li>/api/get_posts?type={string}&cat={int}&count={int}&page={int}</li>
</ul>
Parameters
<ol>
<li>slug : {string} default: empty post slug</li>
<li>id : {int} default: empty post id</li>
<li>count: {int} default: 5 data display limit</li>
<li>page : {int} default: 1 data display offset</li>
<li>type : {string} default: post post_type</li>
</ol>

EDC REST API

Fetch the content of the sections and articles and search them through the API

svrooij

Since wordpress version 4.9.? wordpress includes the functionality provided by this plugin in the core of wordpress.
Checkout https://developer.wordpress.org/rest-api/using-the-rest-api/global-parameters/#_fields for functionality included in the wordpress core, 
they made it even better by filtering the amount of data pulled from the database.
This plugin will no longer be maintained since it has been superseded by the core functionality.
The <a href="https://wordpress.org/plugins/rest-api/" rel="ugc">wp-rest-api-v2</a> returns a lot of properties. 
It could be very useful (or mobile-data-friendly) to only return the properties needed by the application.
If you only want titles and links of some articles it doesn’t make sense to return the content or the excerpt.
This isn’t limited to posts, it also works on custom posttypes, categories, pages, terms, taxonomies and comments.
Instead of returning:
<pre><code>{
 "id": 2138,
 "date": "2015-10-25T15:31:03",
 "guid": {
 "rendered": "http://worldofict.nl/?p=2138"
 },
 "modified": "2015-10-25T15:31:03",
 "modified_gmt": "2015-10-25T14:31:03",
 "slug": "rechtenvrije-fotos",
 "type": "post",
 "link": "http://worldofict.nl/tip/2138-rechtenvrije-fotos/",
 "title": {
 "rendered": "Rechtenvrije foto’s"
 },
 "content": {
 "rendered": ".. A lot of content .. "
 },
 "excerpt": {
 "rendered": " .. A lot of content ..."
 },
 "author": 2,
 "featured_image": 2139,
 "comment_status": "open",
 "ping_status": "open",
 "sticky": false,
 "format": "standard",
 //.. even more tags ....
}
</code></pre>
It can return (with <code>fields=id,title.rendered,link</code> as GET parameter)
<pre><code>{
 "id": 2138,
 "link": "http://worldofict.nl/tip/2138-rechtenvrije-fotos/",
 "title": {
 "rendered": "Rechtenvrije foto’s"
 }
}
</code></pre>
<h4>Notes</h4>
<ol>
<li>If you specify fields so it wouldn’t return data the default response is send back to the client.</li>
<li>(for developers) something wrong with this plugin? <a href="https://github.com/svrooij/rest-api-filter-fields/" rel="nofollow ugc">Github</a></li>
<li>If you liked the plugin <a href="https://github.com/sponsors/svrooij" rel="nofollow ugc">consider sponsoring me</a></li>
</ol>

REST API – Filter Fields

This is hands-down the best REST API extension available.

Best REST API plugin

Filter the properties returned by the Wordpress rest api V2 (only needed until wordpress 4.9)

EDC REST API vs REST API – Filter Fields