Hello,
We apologize for the issue you are facing with the API Error: HTTP 400 while trying to use the SEO analyzer on your website. This error typically indicates that the server is unable to process your API request due to a client error. Here are some common reasons and potential fixes:
-
Website Under Maintenance: Ensure that your website is not in maintenance mode. If it is, switch it back to normal mode.

-
Check Website Status: Verify that your website is returning a 200 status code. You can check the status of your website here. Enter your URL and click Check Status.

-
API Timeout: If your website takes more than 30 seconds to load, this could result in a timeout error.
-
API Requests Blocked by Firewall: Your server’s firewall may be blocking our API requests. If this is the case, you will need to whitelist the IP 46.30.211.100
and the user-agent RankMathApi/2.0.2; https://rankmath.com
.
-
Locally Hosted Website: The SEO Analyzer module only works on live sites that return a 200 OK status when crawled from an external site. If your site is hosted locally, the SEO Analyzer will not function properly.

Please check these points and see if any apply to your situation. If you continue to experience issues, please reply to this ticket, and a human agent from the Rank Math Support team will assist you further.
Sources:
Why Am I Getting "API Error: HTTP 400" Error » Rank Math
Why Am I Getting "API Error: HTTP 400" Error » Rank Math
This is an automated reply from Rank Math Support Bot. If you need further assistance, please reply to this topic and a human support agent will reply to you shortly.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.