APIs CCBill API GuideCCBill API: Cancel Subscription CCBill API: Direct Discount APICCBill API: Charge by Previous Transaction ID CCBill API: Advanced Dynamic UpgradesWebhooks User Guide Data Link Extract System User GuideManaging Multiple Products CCBill Velocity ControlsSubscription Upgrade System Guide Subscription Upgrade System Addendum A: Dynamic UpgradesSubscription Upgrade System Addendum B: One-Click Upgrades