I built Rewind: A zero-dependency TIME-TRAVEL DEBUGGER with live in-browser hot-patching

Description and use

Rewind is a universal time-travel debugger that lets developers quickly locate and fix bugs across Python, Node.js, Go, and other runtimes without external dependencies.

Problem

Debugging modern applications is painful due to reliance on console logs or forward stepping, which can miss the exact mutation causing a crash.

Outcome

Rewind enables developers to quickly identify and fix bugs across multiple runtimes without adding dependencies or slowing execution.

Workflow

• 1. Install Rewind via pip or clone the repo
• 2. Run a script or command with rewind run script.py or rewind exec "node server.js"
• 3. When execution ends or an exception occurs, Rewind launches a local cockpit at http://localhost:8765
• 4. Use the timeline scrubber to navigate to the problematic state
• 5. Inspect variable mutations and state diffs
• 6. Edit code in the browser sandbox and replay to verify the fix
• 7. Apply the patch to disk if desired

Evidence

Rewind was designed with three foundational principles: Universal Multi-Runtime Tracing, Sub-Microsecond Circular State Diffing, and In-Browser Time Scrubber & Live Hot-Patching.

Source

Rewind launches a local interactive cockpit at http://localhost:8765 when execution finishes or hits an unhandled exception.

Source