Hi Ajit – what are you using to POST – ? – Insomnia, Postman or another testing client, or are you writing code in a language – ?
There are instructions for Insomnia posted at the end of the PDF documentation.
If you’re working in a language, check out the resources for PHP, Python and R linked in the list of free resources on the XBRL Data Community. Briefly, you need to POST body, and encoding to the token URL, then use the access_token as “Bearer $token” with your query.
If you’re still having an issue, post back and share the code you have and language you’re using.
David