I am looking for alternatives to stripe's per-user pricing subscription : I need :
to charge my user a recurring payment which depends on the number of user accounts he has
to be able to change the number of users via an API, with customer validation is ok, but ideally without changing a plan nor creating a new type of plan. Check status, cancel, etc. via the API too.
Ideally with no up-front charge = fee + percentage of transaction
I found out that stripe might be a good option (see per-user pricing here https://stripe.com/docs/subscriptions) and unfortunately Paypal does not seem to offer this kind of feature (plans can only be increased by 20% each 180 days or you need to cancel previous profile and create a new one). Or am I mistaking about Paypal ?
What alternatives would exist for such needs?
What you want are Reference Transactions, in which case you run an original authorization or sale transaction, and then in the future you'd run DoReferenceTransaction with the original transaction ID and any new amount you need to process. It will process immediately without any redirection or additional authorization required at that point.
If you use reference transactions with Payments Pro (direct credit cards) then all you need to do is save the original auth or sale transaction ID to your database so that you can pull it out for the user when you need to process a future payment using DoReferenceTransaction.
For PayPal payments you'll use Express Checkout w/ Billing Agreements, which will give you back a billing agreement ID. In that case, the billing agreement ID is what you'd pass into future calls to DoReferenceTransaction.
In either case you'll need to build your own system to lookup payments that need to be processed each day and loop through them making a call to DoReferenceTransaction for each one.