Coin Pinger

Coin Pinger is a browser-based acoustic test that authenticates gold and silver coins by analyzing their ring. It addresses the problem of detecting counterfeit bullion by comparing a coin's resonance fingerprint against a calibrated reference from a known genuine example.

The process begins with calibration: a user balances a genuine coin on a fingertip, taps its edge, and saves the resulting ring as a named reference such as "Gold Maple" or "Silver Eagle". To test a suspect coin, it is tapped and the tool checks whether its ring matches every reference peak within ±3 percent. A verdict of MATCH or NO MATCH is provided, supplemented by optional checks against official mint specifications for weight and dimensions. The application detects the coin's c0d2, c0d3, and c0d4 vibration modes with sub-Hz precision and evaluates ring decay rate, noting that solid precious metal rings longer while other alloys decay faster.

It operates entirely on-device with audio that never leaves the browser. Users can share calibrated references via links or JSON files so others can test against the same verified fingerprint. Built-in tables supply official mint weights and sizes for common bullion coins along with sensible tolerances. The tool installs as a progressive web app and requires no signup.

Coin Pinger is provided free of charge. It is intended for bullion stackers and coin collectors who seek a private verification method without external data transmission.