Is someone living in Israel allowed to do online checkin for an American, for a Motzei Shabbos flight?
לא הביישן למד... ולא הקפדן מלמד.
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Besides, everything is automated; no person does anything when you check in online.
שביתת כלים
You don't need to be 100% positive. If the company is not Jewish, you don't need to be חושש that they have a Jewish employee working on your reservation. Besides, everything is automated; no person does anything when you check in online.
They're not your כלים.