This is a conversation API site, so please visit SimSimi's official blog.
SimSimi official blog : http://blog.simsimi.com
No. SimSimi API is not free. You can purchase paid key on http://developer.simsimi.com/pricing
But You can Trial 7 day for Testkey. It's limited 100 calls/day
Signup on Simsimi developer site for free. http://developer.simsimi.com/signUp
If you want to have more daily quota or commercial use,
You should purchase Simsimi AICR API package. for more details on http://developer.simsimi.com/pricing
Did you use Trial-key's request URL? paid-key and trial-key are different request URL. You used a paid-key URL but it does not work normally, please send the URL to firstname.lastname@example.org
You can use simsimi's default filtering function. (check "ft" parmater in request paremeter) It's just optional function. Its performance is not good except in Korean. SimSimi Inc. DO NOT gurantee the quality of the function.
If there are keywords you should not include, please let me know it by email email@example.com. If it is obviously an inappropriate word, I will modify our DB to ensure it is not included in the answers.
Extra Function are available only to conversaion API buyers and will require payment of additional fees. Procedure for applying for extra Function is as follows.
1) Purchase a conversation API.
2) On the API Configuration page, click the [Apply for extra function] button, and write the application form.
3) Reply to the confirmation email you received.
4) After receiving the invoice for the applied extra features, pay with PayPal.
You can not sign up on the Chinese network because of the Great Fire Wall issue.