A simple ICalendar with no requirement for external libraries

ICalendarSimple.razor

@if(IsValid)
{
    <a href=@dataUrl download=@Filename >@ChildContent</a>
}
@code
{
    [Parameter] public DateTime? Start { get; set; }

    [Parameter] public DateTime? End { get; set; }

    [Parameter] public string Summary { get; set; }

    [Parameter] public string Description { get; set; }

    [Parameter] public RenderFragment ChildContent {get;set;}

    [Parameter] public string Filename { get; set; } = "Calendar.ics";

    string dataUrl => GetDataUrl();

    string GetDataUrl()
    {
        var text = GetCalendarText();
        var data = System.Text.Encoding.UTF8.GetBytes(text);
        var base64 = Convert.ToBase64String(data);
        return $"data:text/calendar;base64,{base64}";
    }

    bool IsValid => (Start.HasValue && End.HasValue);

    string GetCalendarText()
    {
        var id = Guid.NewGuid().ToString();
        return
$@"BEGIN:VCALENDAR
PRODID:-//BlazorICalendar//NONSGML BlazorICalendar//EN
VERSION:2.0
BEGIN:VEVENT
DESCRIPTION:{Description}
DTEND:{GetDate(End)}
DTSTAMP:{GetDate(DateTime.UtcNow)}Z
DTSTART:{GetDate(Start)}
SEQUENCE:0
SUMMARY:{Summary}
UID:{id}
END:VEVENT
END:VCALENDAR";
    }

    private string GetDate(DateTime value)
    {
        return value.ToString("yyyyMMdd\THHmmss");
    }
}

A really simple ICalendar generator with no library imports. Set the Start and End dates and the optional Summary and Description fields.
e.g.

<ICalendarSimple Start="@DateTime.Now.AddHours(1)" End="@DateTime.Now.AddHours(2)" Summary="Example" Filename="Meeting.ics" >Add Meeting to my Calendar</ICalendarSimple>

Warning: this is rough-and-ready, I haven't really checked how the descriptions/summary should be encoded, or how dates and timezones are supported.