Simple awk csv to ndjson converter.

csvjson.awk

BEGIN {
  FPAT = "([^,]*)|(\"[^\"]+\")"
}

NR == 1 {
  split($0, header, ",")
}

NR > 1 {
  printf "%s", "{"
  for (i = 1; i <= NF; i++) {
    key=header[i]
    val=$i
    gsub("^\"+", "", val) # remove leading double quotes
    gsub("\"+$", "", val) # remove trailing double quotes
    gsub(/\\/, "\\\\", val) # json escape backslash
    gsub(/"/, "\\\"", val) # json escape double quote
    if (val !~ /^0+/ && (val ~ /^[0-9]+$/ || val ~ /^[0-9]*[.][0-9]*$/)) {
      format = "\"%s\":%s"
    } else {
      format = "\"%s\":\"%s\""
    }
    printf format, key, val
    if (i != NF) printf "%s", ","
  }
  printf "%s\n", "}"
}