Sumit Kumar - Projects

Real-time collaborative editing is usually associated with either a SaaS product or a genuinely heavy CRDT implementation. Codepad takes a lighter path: it's built on operational transformation (OT), the same class of algorithm behind early Google Docs, and it's designed to be small enough to self-host without provisioning a database at all.

The architecture splits cleanly across three layers. The server is Rust, using the `warp` web framework and the `operational-transform` crate for the actual OT logic, storing documents as in-memory data structures rather than rows in a database — that's what keeps the whole thing fast and keeps testing simple, at the cost of documents being transient by default (garbage-collected after 24 hours of inactivity, or lost on a server restart, unless persistence is turned on). The OT transformation logic itself is compiled to WebAssembly via wasm-bindgen so the exact same conflict-resolution code runs client-side in the browser as runs on the server. The frontend is TypeScript and React, with Monaco — the actual editor component from VS Code — as the text editing surface, talking to the server over a plain WebSocket connection.

Configuration is entirely environment-variable driven: EXPIRY_DAYS controls garbage collection, SQLITE_URI optionally turns on snapshot persistence to a local SQLite file (so documents survive restarts if you want that), and PORT/RUST_LOG cover the basics. The whole thing ships as a 6 MB Docker image with multi-platform support for linux/amd64 and linux/arm64, published to Docker Hub — docker pull sumitkumar17/codepad and you have a fully self-hosted collaborative editor with zero external dependencies.