What is an eSignature API?
An eSignature API is a set of REST endpoints that lets developers add electronic signature collection to any application or workflow. Instead of building signing functionality from scratch — handling document delivery, signature capture, authentication, audit trails, and PDF storage — you call the API and it handles all of it.
How it works
Your application sends a document to the API with recipient details (name, email, role) and field positions (where the signature, date, and text fields should appear). The API notifies recipients by email. Recipients open a signing link on any device — desktop, tablet, or mobile — and complete their signature. When all parties have signed, the API sends a webhook event to your application and makes the completed signed PDF available for download.
What a typical eSignature API request looks like
- Your app calls the API with a template ID or a PDF file
- You specify recipients, their roles, and signing order
- The API sends the document for signing
- Recipients sign on any device, in any browser
- You receive a webhook when the document is completed
- You download the signed PDF with an audit trail attached
When to use an eSignature API vs eSignature software
Use an eSignature API when you need to embed signing into your own application, automate document workflows programmatically, or process high volumes of documents without manual steps. Use standalone eSignature software (like Docusign’s web app or BoldSign’s dashboard) when your team needs to send and manage individual documents without a custom integration.
What eSignature API by CraftMyPDF includes
eSignature API combines document generation and e-signature collection in one platform. You can build a PDF template, populate it with dynamic data, and send it for signing in a single API call — with no second tool required. The API supports draw, type, and upload signatures, five recipient roles, ten field types, sequential and parallel signing, and webhooks.