TL;DR: Free Hong Kong ID validator: checks the letter prefix, six digits, and parenthesized check character (weighted mod 11) locally. Format validation only.
This tool runs entirely in your browser. Open DevTools → Network panel and search your input — it appears in no request.
Usage Guide
A Hong Kong ID is 1-2 letters + 6 digits + a parenthesized check character (parentheses often omitted in everyday use). This tool validates with the publicly circulating algorithm: letters map A=1..Z=26, a single letter aligns to the second slot, weights [9,8] over the letter slots and [7,6,5,4,3,2] over the digits, then the 11-complement of the weighted sum mod 11 — remainder 10 encodes as A. Run cross-border form inputs through it to catch typos.
1. Algorithm and pitfalls
Two classic traps: parentheses — some forms keep them, some drop them, this tool accepts both; and a check character of A — it is not a letter in disguise but the encoding for remainder 10 (analogous to the trailing X on mainland IDs). Note the algorithm is the publicly documented version; the Immigration Department publishes no official spec, and format-valid says nothing about issuance.