"Invalid Client Id " while retrieving access token

I get Invalid Client when I try to get access token via token url
I have checked all my configs and everything is set

Are you going through an authorization code grant?

Yes. The thing is I can connect via API access link which you have provided by specifying clientid and secret. However when I try via code it doesnt work.

So you are first requesting a new authorization code from https://accounts.infusionsoft.com/app/oauth/authorize then attempting to get a token via an authorization_code grant using the returned code? If so need to know what the request for the token looks like (body and headers, but redact sensitive info like the secret.)

Ok now invalid client id isnt aparing. However I dont get the access token

What does the response look like. Also make sure you are sending the exact same redirect_uri that you used to get the original authorization code. Also it looks like you are manually creating these requests. You might want to try the built in OAuth 2.0 Authorization in Postman (it can save you a little work).

Response shows me what i showed you in screenshot above and Yes am sending the same redirect_url

The screenshot is showing the body of the request. I need the body of the response (further down in postman).

Something I just noticed in your Postman screenshot that I didn’t see before is the wrong Content-Type. It should be x-www-form-urlencoded.