Terms & Legal

Short version: Coin Pinger is a free, open-source (MIT) acoustic ping-test tool. It's a first-pass authenticity signal, not proof, and not financial or professional advice. Coin data comes from official mint specifications and public acoustic-physics modeling; we're independent and not affiliated with any mint or other coin-testing product.

Coin Pinger measures the acoustic resonance of a coin you tap, and compares it to reference ranges (preset or ones you calibrate yourself) to help you judge authenticity. It is a convenience tool for a first-pass check. The ping test is one signal, not proof: results vary with your microphone, how you hold and strike the coin, wear, and environment. Coin Pinger does not provide financial, investment, grading, or professional authentication advice, and is not a substitute for a professional assayer, grader, or dealer.

Our preset coin references combine several public sources:

• Physical specifications (weight, diameter, thickness, fineness) are taken from the issuing mints' published data; each per-coin guide page links its source (e.g. U.S. Mint, The Royal Mint, Royal Canadian Mint, Perth Mint, Austrian Mint), with Numista or manufacturer spec sheets used where a mint does not publish a figure.
• Expected resonance ranges are computed by us from first-principles free circular-plate vibration theory — the closed-form model of A. W. Leissa, Vibration of Plates, NASA SP-160 (1969), a public-domain U.S. Government publication, with dimensionless mode parameters from R. C. Colwell & H. C. Hardy, Philosophical Magazine (1937). Each coin's modes are calculated from its published dimensions and standard published metal constants (Young's modulus, density, Poisson ratio), with a fixed rim/relief correction; the least-certain group (.9999 gold) is given a wider tolerance and anchored by direct measurement over time. We publish them as guidance ranges (typical bands), not exact values, and round and set tolerances ourselves.
• Corroborating literature. The same acoustic model, and coin authentication by resonance, are established in the peer-reviewed and institutional record — e.g. Lawrence Livermore National Laboratory, Resonant Acoustic Characterization of Coins (LLNL-TR-829101), and T.-P. Dao et al., Sensors 22(23):9055 (2022).
• Our own growing sample database. To refine these references over time, we are building a database of anonymous acoustic samples — the measured numbers only (peaks, tolerances, size, match result), never audio. Every preset coin pinged in the app contributes a sample: you are opted in by default and can turn it off any time with the toggle in the app. It never includes your own calibrated coins. The mathematical model remains primary; the samples are a secondary, corroborating check. See our Privacy Policy.
• The ping/ring test itself is a long-established, well-known method, and the vibration-mode notation (c0d2/c0d3/c0d4) is standard physics nomenclature.

Full derivation, the material-constants table, our cross-validation results, and complete citations are on our Methodology page. Coin Pinger is an independent project and is not affiliated with, endorsed by, or sponsored by any mint, refiner, or other coin-testing application.

Coin names and mint names (for example American Silver Eagle, Krugerrand, Britannia, Maple Leaf, Philharmonic) are trademarks of their respective owners. They are used here for identification and reference only, and their use does not imply any affiliation or endorsement.

Coin Pinger is provided free of charge, "as is" and "as available," without warranties of any kind, express or implied, including merchantability, fitness for a particular purpose, and accuracy of results. You use it at your own risk. To the maximum extent permitted by law, the authors and contributors are not liable for any loss or damage — including financial loss from buying, selling, or valuing precious metals — arising from your use of, or reliance on, the app or its data. For high-value or disputed items, obtain an independent professional opinion.

Coin Pinger is open source under the MIT License, and the license covers the whole project — the source code, the preset coin reference data, documentation, and website content. You are free to use, copy, modify, and redistribute any of it, including commercially, provided the copyright and license notice are preserved. Everything is provided on an "as is" basis.

MIT License

Copyright (c) 2026 Coin Pinger and contributors

In this license, "the Software" means the entire Coin Pinger project — its
source code, the preset coin reference data, documentation, and website
content — not only the program code. It is licensed for any use, including
commercial, under the terms below.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Your microphone audio and coin library never leave your device; we use only aggregate analytics. Full details in the Privacy Policy.

If these terms change, the effective date above will be updated and the revised version posted here. Questions: contact@coinpinger.com.