OpenSign

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.