Some models on our website are free to run without having to create an account. However, more advanced features are marked as “pro”. To be able to use those features you need to be signed in (creating an account is free) and have sufficient number of credits on your account.
When any “pro” feature is activated, the note next to the “Calculate” button shows how many credits are required to run the calculation. If you need more credits, please contact us at [email protected] . While our service is in the pre-release stage we will add credits without any charge. In the future you will be able to buy credits.