The latest articles on DEV Community by Roushan kumar (@roushan71262). https://dev.to/roushan71262 https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F3964219%2Fcd8ff56e-97cd-4005-a2c2-57e5dc5cd55a.jpg https://dev.to/roushan71262 en Roushan kumar Mon, 24 Aug 2026 05:45:47 +0000 https://dev.to/roushan71262/building-an-open-source-zero-knowledge-docsend-alternative-with-react-19-and-supabase-3oap https://dev.to/roushan71262/building-an-open-source-zero-knowledge-docsend-alternative-with-react-19-and-supabase-3oap <h1> Why We Built DocTransfer </h1> <p>Sharing sensitive documents like pitch decks, financial reports, or legal contracts shouldn't require paying $250+/month for platforms that store your unencrypted files on their servers.</p> <p>We built <strong><a href="https://doctransfer.app" rel="noopener noreferrer">DocTransfer</a></strong> (and open-sourced it on <a href="https://github.com/simplegithubs/DocTransfer3949" rel="noopener noreferrer">GitHub</a>) as a privacy-first, client-side encrypted document sharing and Virtual Data Room (VDR) platform.</p> <h2> Zero-Knowledge Cryptography Architecture </h2> <p>Most document-sharing services encrypt files <em>at rest</em> on their cloud storage. That means their backend servers - and anyone with access to them - can view your raw documents.</p> <p>In <strong>DocTransfer</strong>, encryption happens entirely on the client before the payload leaves your browser:</p> <ol> <li> <strong>Client-Side OpenPGP &amp; AES-256-GCM</strong>: Files are encrypted in the browser using the WebCrypto API and OpenPGP.js.</li> <li> <strong>Zero-Knowledge Key Handling</strong>: Encryption keys are kept in URL hash fragments (<code>#key=...</code>), which are never sent to our servers.</li> <li> <strong>Dynamic Forensic Watermarking</strong>: Recipient email overlays are rendered dynamically on the canvas layer, preventing unauthorized screenshots and distribution.</li> </ol> <h2> Tech Stack &amp; Key Features </h2> <ul> <li> <strong>Frontend</strong>: React 19, TypeScript, Vite, Framer Motion</li> <li> <strong>Database &amp; Auth</strong>: Supabase (PostgreSQL with strict Row-Level Security, Edge Functions, Storage)</li> <li> <strong>Document Processing</strong>: <code>pdf-lib</code>, <code>react-pdf</code>, <code>pdfjs-dist</code> </li> <li> <strong>Security &amp; Signatures</strong>: OpenPGP.js, SimpleWebAuthn (Biometric sign-in), Digital Certificate generation</li> <li> <strong>Analytics</strong>: Real-time page-by-page engagement heatmaps &amp; viewer telemetry</li> </ul> <h2> Try It &amp; Contribute </h2> <ul> <li> <strong>Live App</strong>: <a href="https://doctransfer.app" rel="noopener noreferrer">doctransfer.app</a> </li> <li> <strong>GitHub Repository</strong>: <a href="https://github.com/simplegithubs/DocTransfer3949" rel="noopener noreferrer">github.com/simplegithubs/DocTransfer3949</a> </li> </ul> <p>We would love to get your feedback on the client-side encryption flow, PDF rendering optimizations, and general user experience!</p> opensource showdev webdev security