Real-time Effect span streaming to frontend UIs. Stream traces from any backend to React with zero overhead.
livetrace is an open-source library that streams real-time progress updates from backend workflows directly into React-based user interfaces. Developers wrap their existing Effect-based code with a simple function, and users immediately see every step—parsing documents, running AI agents, indexing data—as it happens in the browser. The library supports multiple transport options (SSE, WebSocket, durable streams) and requires zero Effect knowledge on the frontend, making it easy to add live progress UIs to any application.
How It Works
You hear about livetrace—a tool that lets your users watch what your backend is doing in real time, like peeking inside a black box.
You add a single wrapper function around your existing code, and suddenly every step—parsing, embedding, searching—becomes visible to the outside world.
You choose a transport: simple one-way streaming, a two-way connection, or a durable log that survives page reloads. The library handles the wiring for you.
Show users a progress bar as a PDF gets parsed, chunked, embedded, and indexed—step by step as it happens.
Let users watch an AI agent plan, search, rerank, and generate—streaming tokens and results in real time.
As your backend works, cards appear on screen showing each step starting, running, and finishing—with logs and progress bars updating in real time.
Instead of a spinning loader, users see exactly what's happening—every parse, every search, every token. They trust the system because they can see it working.
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