Validate URL in a Google Spreadsheet
Formula to check if URL in cell A1
in a Google Spreadsheet is up, using the W3C HTML Checker API
Formula
=IF(A1<>"",IF(ISERROR(FIND("non-document-error", INDEX(IMPORTDATA("https://validator.w3.org/nu/?out=json&doc=" & A1),0,2))),"✓","✗"),"")