Start with installing a plugin WordPress REST API on your wordpress site

Second, install Chrome Plugin called “POSTMAN” on your PC

To access the JSon
Open Postman with GET
type : http://your-site-name/wp-json/wp/v2/

To view all posts
GET http://your-site-name/wp-json/wp/v2/posts/

To view specific posts/pages, use its id

GET http://your-site-name/wp-json/wp/v2/posts/<post id>

GET http://your-site-name/wp-json/wp/v2/pages/<page id>

Example :

GET http://your-site-name/wp-json/wp/v2/posts/30

GET http://your-site-name/wp-json/wp/v2/pages/10

For view 10 available categories

GET http://your-site-name/wp-json/wp/v2/categories

To view specific category id

GET http://your-site-name/wp-json/wp/v2/categories/<category id>

Example

GET http://your-site-name/wp-json/wp/v2/categories/3

Filter specific category name will bring all slugs under that category

GET http://your-site-name/wp-json/wp/v2/posts?filter[category name]=categoryname

example
GET http://yoursitename/wp-json/wp/v2/posts?filter[category_name]=wordpress

Filter specific category id

GET http://your-site-name/wp-json/wp/v2/posts?filter[cat]=<categoryid>

example

GET http://your-site-name/wp-json/wp/v2/posts?filter[cat]=4

Tags behave the same way as category

GET http://your-site-name/wp-json/wp/v2/terms/tag

To display all available tags

http://your-site-name/wp-json/wp/v2/terms/tag?per_page=0

Tags based on id

GET http://your-site-name/wp-json/wp/v2/terms/tag/

Filters based on slug

GET http://your-site-name/wp-json/wp/v2/posts?filter[tag]=<tagid>

Filters based on tag id

GET http://your-site-name/wp-json/wp/v2/posts?filter[tag_id]=<tagid>

Common Routes for Users

GET http://your-site-name/wp-json/wp/v2/users

Current logged in user

GET http://your-site-name/wp-json/wp/v2/users/me

Users based on id

GET http://your-site-name/wp-json/wp/v2/users/

example

GET http://your-site-name/wp-json/wp/v2/users/<user id>

Example

GET http://your-site-name/wp-json/wp/v2/users/2

Common Routes for comments

GET http://your-site-name/wp-json/wp/v2/comments

Comments based on id [will return 10 latest comment on that post]

GET http://your-site-name/wp-json/wp/v2/comments?post=<comment id>

example

GET http://your-site-name/wp-json/wp/v2/comments?post=3

For all comments on specific posts

GET http://your-site-name/wp-json/wp/v2/comments?post=3&per_page=0