Checkbook's Digital Checks are a way for businesses to send and receive funds via email - with instant deposit and next-day fund credits. All you need is a single API call with an email address and you can do ACH, RTP, P2C or Check21. The recipient does not need to signup or provide bank information before receiving the payment With their effortless on-boarding, Checkbook offers easy adoption combined with the low-cost of ACH while preserving payment immediacy.