Calendars · Global01
World calendars & era systems
Compare the same date across Gregorian, Japanese era, Minguo, Buddhist, Hijri, Persian, Hebrew, Chinese and other calendar systems.
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Global · Formats02
World date format reference
Compare common date conventions around the world and use ISO 8601 safely for data exchange.
Global · Formats03
World number format reference
Compare decimal separators, grouping and percent formats across major locales.
Global · Codes04
Country & region code reference
Search ISO 3166-1 alpha-2, alpha-3 and numeric country/region codes.
Global · Codes05
Currency code & symbol reference
Look up ISO 4217 alphabetic/numeric codes and common symbols for major currencies.
Units · Global06
SI prefixes & units reference
Reference SI prefixes from quetta to quecto and the seven SI base units.
Units · Images07
World paper size reference
Compare ISO A/B/C, JIS B, US Letter/Legal and other common paper sizes in mm and inches.
Units · Global08
Cooking measure reference
Compare cups, tablespoons, teaspoons and metric cooking measures, including regional differences.
Units · Data09
Digital storage unit reference
Understand decimal KB/MB/GB/TB and binary KiB/MiB/GiB/TiB.
Units · Images10
DPI, PPI, px, mm & inch reference
Understand DPI/PPI and the relationship between pixels and physical dimensions.
Images11
Image aspect ratio reference
Reference common aspect ratios such as 1:1, 4:3, 3:2 and 16:9.
Images · Web12
Image file format reference
Compare JPEG, PNG, WebP, AVIF, GIF and SVG and choose the right image format.
Data13
CSV & TSV reference
Reference CSV/TSV delimiters, quoting, line breaks and media types.
Data · Web14
Character encoding & BOM reference
Compare UTF-8, UTF-16, Shift_JIS and BOM behavior.
Data · Web15
Line ending reference
Compare LF, CRLF and CR line endings and common interoperability issues.
Data · Global16
ISO 8601 date & time reference
Reference ISO 8601 dates, times, UTC designator and offsets.
Web17
HTTP status code reference
Quickly look up common HTTP 1xx–5xx status codes.
Web · Codes18
MIME type & extension reference
Search and copy common IANA media types and filename extensions.
Web · Codes19
HTML entities & Unicode reference
Reference common HTML character references and Unicode code points.
Web · Data20
Regular expression cheat sheet
Quick reference for regex character classes, quantifiers, anchors, groups and flags.
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