OpenSign is an open-source electronic signature (e-signature) platform focused on signing and managing PDF documents. It provides a web-based workflow for preparing documents, collecting signatures from one or multiple parties, and maintaining traceability through audit logs and completion certificates.

Key Features

PDF signing with multiple signature input options (drawn, typed, uploaded, and saved signatures)
Multi-signer workflows with link-based invitations and optional signing order
Document annotations and reusable PDF templates for repeatable signing processes
Email-based OTP verification for guest signers
Document expiry and signer rejection with reason tracking
Audit trails with timestamps and request metadata, plus generated completion certificates
Built-in document vault features for storing and organizing signed documents
API access via API keys for integration with external systems

Use Cases

Sending contracts and agreements for signature with an auditable completion record
Creating reusable templates for HR, sales, procurement, or onboarding paperwork
Embedding or integrating signing into internal tools using an API

Limitations and Considerations

Requires an external persistent MongoDB configuration to retain data reliably in some deployment setups

OpenSign is a strong choice for teams that need a self-managed e-signature workflow with multi-signer support, templates, and auditability. It aims to cover core commercial e-sign platform features while remaining free and open source.