OpenSign is a self-hosted, open-source alternative to commercial e-signature platforms like DocuSign, PandaDoc, and Adobe Sign. Built with React.js, Node.js, and MongoDB, it provides a complete document signing workflow including secure PDF annotations, multi-signer sequences, email OTP verification, and audit trails. Designed for businesses and teams seeking full control over their document signing processes without vendor lock-in, OpenSign enables organizations to deploy a compliant, customizable e-signature solution on their own infrastructure. The platform supports integration with cloud storage, CRMs, and Zapier, making it suitable for legal tech, HR departments, and compliance-focused workflows.
OpenSign’s architecture emphasizes security and transparency. All document signing activities are logged with timestamps, IP addresses, and user details, and completion certificates are automatically generated. With a clean UI and support for handwritten, typed, or image-based signatures, it delivers an enterprise-grade experience while remaining free and open under the AGPL-3 license.
What You Get
- Secure PDF E-Signing - OpenSign uses robust encryption to sign and verify PDF documents with digital signatures that comply with e-signature standards, supporting both authenticated users and guest signers via email OTP.
- Annotate Documents - Users can add handwritten, typed, or image-based signatures directly on PDFs using an intuitive drawing pad, with support for saving signature templates for reuse.
- Multi-signer Workflows - Invite multiple signers to a document with configurable signing order, and enforce sequential or parallel signing sequences for complex approval processes.
- Email OTP Verification for Guest Signers - Non-registered users can sign documents only after verifying their identity via a one-time code sent to their email address.
- Expiring Documents & Rejection Reason - Set expiration dates for documents to prevent late signing, and allow signers to reject a document with a customizable reason that notifies the sender.
- PDF Template Creation - Create, store, and reuse PDF templates with pre-defined signature fields to streamline recurring signing processes like NDAs or contracts.
- OpenSign™ Drive - A centralized, secure document vault for organizing, sharing, archiving, and signing files with folder structures and access controls.
- Audit Trails & Completion Certificates - Every action on a document (view, sign, reject) is logged with timestamp, IP, email, and device info; a cryptographically verifiable completion certificate is generated upon final signing.
- API Support - Full RESTful API with key-based authentication to integrate OpenSign into existing systems for automated document signing workflows; detailed documentation available at https://docs.opensignlabs.com/docs/API-docs/v1.1.
- Zapier & Cloud Integrations - Connect OpenSign to 5,000+ apps via Zapier and integrate with cloud storage platforms like Google Drive or Dropbox for seamless document handling.
- Customizable Email Templates - Modify the design and content of invitation, reminder, and completion emails to match your brand identity without code changes.
Common Use Cases
- Building a legal tech SaaS platform - Law firms or document automation startups use OpenSign to offer branded e-signature capabilities without paying per-document fees from DocuSign or Adobe Sign.
- Creating a multi-department HR onboarding system - HR teams deploy OpenSign to collect signed employment contracts, NDA forms, and policy acknowledgments from new hires with audit trails for compliance.
- Problem: High cost of commercial e-signature tools → Solution: Self-hosted OpenSign - Organizations with high document volume (e.g., real estate agencies, insurance brokers) reduce licensing costs by migrating from DocuSign to a self-hosted OpenSign instance with full data control.
- DevOps teams managing compliance workflows - Teams in regulated industries (finance, healthcare) use OpenSign’s audit logs and API to embed secure signing into internal approval systems while meeting GDPR, HIPAA, or eIDAS requirements.
Under The Hood
OpenSign is a web-based document signing and collaboration platform designed to provide flexible, customizable digital signature workflows with support for multi-language interfaces and cloud integration. The project emphasizes a modular frontend architecture built on React, paired with a Parse Server backend that enables scalable business logic and API handling.
Architecture
OpenSign adopts a monolithic yet modular structure that promotes clear separation of concerns through component-based organization and layered backend services.
- The frontend is organized into reusable React components with feature-specific modules, supporting a well-defined modular approach.
- The backend integrates Parse Server to manage core logic and custom API endpoints, enabling decoupled data access and application flow.
- Design patterns such as component composition, drag-and-drop interactions, and theme-based rendering are consistently applied across the codebase.
- State management is handled via React and Redux, ensuring predictable data flow from parent to child components.
Tech Stack
The project leverages modern JavaScript and React technologies, supported by a rich ecosystem of tools for development, styling, and testing.
- Built with JavaScript and React, using Vite as the build tool for fast development and optimized production builds.
- Employs libraries like react-i18next, axios, pdf-lib, and react-dnd to deliver internationalization, API communication, PDF handling, and drag-and-drop functionality.
- Styling is managed through Tailwind CSS and PostCSS with DaisyUI for consistent UI component design.
- Testing is conducted using Vitest and React Testing Library, complemented by ESLint and Prettier for code linting and formatting.
Code Quality
The project exhibits mixed quality with some structured practices but lacks comprehensive test coverage and implementation depth.
- Code linting and formatting are configured, indicating a baseline level of code consistency and style enforcement.
- Error handling is implemented in key areas, though not fully comprehensive across all modules.
- Type annotations are present, enhancing code clarity and maintainability in parts of the codebase.
What Makes It Unique
OpenSign distinguishes itself through its flexible document editing capabilities, global accessibility features, and extensible architecture.
- Features a widget-based PDF editor that allows customizable signature placement and form field design for flexible document workflows.
- Offers multi-language localization with support for 6+ languages, making it accessible to a global user base.
- Integrates seamlessly with third-party services and cloud platforms, enabling scalable deployment and extensibility.
- Uses React components and drag-and-drop interfaces to create an intuitive user experience for document creation and signing.