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.
Count number of days between dates. Add days to date. Subtract days from date.
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.