For China-map coordinates, choose the source map correctly. WeChat/Tencent/Amap normally use GCJ‑02; Baidu normally uses BD‑09.
WGS‑84
GCJ‑02
BD‑09
Conversion is performed locally in the browser and does not send coordinates to a server. A WeChat location card may not expose raw coordinates when copied; if it only provides a place name/address, open it in WeChat/Tencent Maps and copy a link or coordinates first.