Data, time, ticks, timestamp, time span
Unix timestamp to date time. Date time to Unix timestamp. Current Unix timestamp.
C# / .NET Core / .NET Framework Ticks (DateTime.Ticks) ⇄ Date Time ⇄ Unix Timestamp three way Converter.
C# / .NET Core / .NET Framework Ticks (TimeSpan.Ticks) ⇄ Time Span (days, hours, minutes, seconds, part of second) Converter.
Days since birthday. Days until next birthday.
Regular expression, checksum
Hash / checksum / fingerprint calculator. Hash from text (string) and file.
Network, hostname, public IP, ping
Check whether Your host / gateway responds to the ping form public network.
Find Your public IP address and hostname.
Pixel: size, count, density. Screen: resolution, aspect ratio, width, height, area.
Check the resolution of own display.
Decimal number to Q format number converter (web version).
Name (.NET culture, English, native), ISO code (639-1, 639-2), Windows (API three letter, LCID), IETF language tag (RFC 4646).
Online reference manuals.
IT vocabulary (words, phrases, expressions, terms): abbreviations, acronyms, shortands, pithy forms.