Paste a number, then click Run.
Tip: you can paste multiple lines. Spaces and dashes are ignored.
Privacy: by default, input is not stored and share links do not include your number.
Tip: you can paste multiple lines. Spaces and dashes are ignored.
Privacy: by default, input is not stored and share links do not include your number.
Luhn checker — Validate numbers with the Luhn algorithm (credit cards, IMEI, etc.). Also calculate the check digit. Browser-only; copy results or share a link.
Example: Use this tool to sanity-check numbers quickly, then share the link if you need to discuss with others.
FAQ: (1) Does it upload my data? No—runs in your browser. (2) Can I share results? Yes—use the share link feature. (3) Is it authoritative? Treat it as a convenience, not professional advice.
Luhn 檢查器 — 用 Luhn 演算法驗證數字（信用卡、IMEI 等），也可計算檢查碼。純前端、可複製結果或分享連結。
範例：用這個工具快速試算與對照結果，需要討論時再把連結分享給對方。
FAQ： (1) 會上傳資料嗎？不會，計算在瀏覽器內完成。 (2) 能分享結果嗎？可以，用分享連結。 (3) 準確嗎？請把它當作便利工具，不是專業建議。