diff4

diff4 provides shareable, visually rendered previews of file changes made by AI coding agents. It addresses the need for developers and users of AI agents to review file modifications in a clear, web-based format rather than traditional terminal diffs. The platform is designed to work with agents such as OpenClaw, Hermes, and is compatible with any AI coding agent.

A core feature of diff4 is its focus on secure sharing. Every file and diff shared through the service is encrypted end-to-end using AES-256-GCM encryption. Files are encrypted locally on the user's machine before being uploaded, ensuring that only ciphertext is stored on the server. The platform employs a zero-knowledge approach, meaning that even the operators of diff4 cannot access the contents of shared files. Access to shared previews is protected by a passphrase, and decryption requires the correct passphrase, with encryption keys derived using PBKDF2 with 600,000 iterations and the Web Crypto API.

diff4 is presented as an open source tool, and is intended for developers or anyone working with AI coding agents who need to review and share code or documentation changes securely. The tool generates web pages for file previews, which can be accessed via unique links.

diff4 positions itself within the class of developer tools focused on file change visualization and secure sharing, particularly in workflows involving AI-generated code changes.