Checkbook.io Node.js API Library

A Node.js library for integrating with the Checkbook.io API to send digital, physical, and direct checks, manage invoices and subscriptions, and handle ACH payments. Version 1.0.0 is stable with a callback-based API. Requires Node >=4, no external runtime dependencies. Key differentiators: supports multiple check types (digital, physical, direct), CSV batch sending, idempotency keys, and OAuth bearer tokens. Release cadence is unknown. Alternatives include direct REST calls or other libraries, but this is the official Checkbook.io wrapper.