ClientSideTools Privacy-First Browser Tools

Web Locks Visualizer

The Web Locks API coordinates work across tabs, but held and pending locks are invisible. This tool snapshots the entire lock queue for the current origin, tracks changes live, and lets you acquire test locks to see exclusive vs shared behavior.

PWA & Browser Storage Local processing Lock state never leaves the browser. Nothing is uploaded.

Tool interface

Introduction

Multi-tab apps use Web Locks to serialize access to shared resources like IndexedDB or sync queues. When a race condition occurs, you need to see who holds what. This visualizer exposes the entire lock queue in real time.

How it works

  • Calls navigator.locks.query() to read held and pending locks.
  • Polls on an interval and logs state changes.
  • Acquires test locks via navigator.locks.request() to demo queueing.
  • Releases held test locks manually or after a timed duration.

Privacy

All queries are local via the Web Locks API. Lock state never leaves the browser. No account, no API key.

Limitations

  • Only inspects the current origin's locks.
  • clientId is opaque and can't be mapped to a specific tab.
  • The Web Locks API is not available in every browser.

FAQ

What is the difference between shared and exclusive locks?

An exclusive lock allows only one holder at a time. A shared lock allows multiple concurrent holders, useful for read-heavy coordination.

Is my data uploaded?

No. Everything runs locally in your browser.

Related tools

Version and changelog

  • Version: 1.0.0
  • Last updated: August 12, 2026
  • Changelog: Initial production release.