Reference & Cheatsheets
427 free reference & cheatsheets tools in the Developer Tools collection — every one runs in your browser with no signup and no uploads. Page 1 of 5.
Regex Tester with Plain-English Explainer
Test regular expressions live and see them explained in plain English.
Regex Builder & Tester
Build, test and debug regular expressions with live match highlighting.
HTTP Accept Headers Reference
Accept, Accept-Encoding, Accept-Language, Accept-Charset with q-value syntax.
Accounting Standard Reference
IFRS vs US GAAP key differences at a glance
Age of Consent by Country Reference
Legal age of sexual consent for countries worldwide with notes
Agile Ceremony Reference
Scrum ceremonies with timeboxes, participants and purpose — scaled to your sprint.
Air Quality Index (AQI) Reference
US EPA AQI categories with health messages and a PM2.5 / PM10 converter.
Aircraft Wake Turbulence Category Reference
ICAO wake turbulence categories: Light, Medium, Heavy, and Super by MTOW.
Altitude & Oxygen Level Reference
Atmospheric pressure and O2 percentage at altitude
Amino Acid Reference Chart
All 20 standard amino acids with abbreviations and properties
Seven Wonders Reference
Ancient, Medieval, and New Seven Wonders with location and date
Android Intent Flags Reference
All Android Intent flags (FLAG_ACTIVITY_*, FLAG_RECEIVER_*) with behavior.
Android Permissions Reference
All Android manifest permissions with protection level and feature requirement.
APA 7th Edition Citation Reference
Quick-reference format for APA 7 citations by source type
Apache Directives Reference
Key Apache httpd directives filterable by context and module.
ARIA Attributes Reference
Every aria-* attribute with value type, allowed roles and state vs property flag
ARIA Roles Reference
All WAI-ARIA roles with required/allowed attributes and accessible name source.
ASCII Code Table Lookup
Look up any ASCII character by code or letter
ASCII Table
Interactive ASCII table with decimal, hex, octal, binary and character columns.
ASEAN Member Reference
All 10 ASEAN members with GDP, population, and accession.
Aspect Ratio Reference
Common display and video aspect ratios with pixel dimensions
Stellar Classification (Spectral Types) Reference
O, B, A, F, G, K, M spectral types with temperature and colour.
Asymmetric Cipher Reference
RSA, ECC, Ed25519, X25519 algorithms with key sizes and use case guidance.
Australian State & Territory Reference
All 6 states and 2 territories with codes and capitals
Aviation Light Signal Reference
ATC light gun signals and their meaning in the air and on ground
AWG Wire Gauge Reference Table
Look up AWG gauge to diameter, area, and ampacity
awk Reference
awk built-in variables, functions and patterns in one searchable cheatsheet.
AWS Region Codes Reference
All AWS regions with code, display name, launch year and opt-in status.
AWS S3 Storage Classes Reference
All S3 storage class names with retrieval time, cost tier and minimum duration.
Azure RBAC Built-in Roles Reference
Common Azure built-in role names with scope levels and permission summary.
Azure Region Codes Reference
All Azure regions with internal name, display name and paired region.
Bandwidth & Data Rate Reference
bps, Kbps, Mbps, Gbps in bits and bytes, with download times.
Bash Arithmetic Operators Reference
All (( )) and let arithmetic operators with precedence and assignment forms.
Bash Commands Cheatsheet
Search bash builtins and common GNU coreutils with syntax and flags.
Bash Parameter Expansion Reference
All Bash parameter expansion forms with substitution, trimming and case modifiers.
Bash Special Variables Reference
Every Bash special variable ($?, $$, $!, $@, etc.) with meaning and scope.
Bash Test Operators Reference
All [ ] and [[ ]] test operators by type — file, string, arithmetic, regex.
Bearing Number Reference
Decode ISO metric bearing numbers to bore, OD, width, and type
Beer Style Reference
BJCP beer style categories with ABV, IBU, and SRM ranges.
Big-O Complexity Reference
Time and space complexity for sorting, searching, data-structure and graph operations in one searchable table
Bitwise Operations Reference
AND, OR, XOR, NOT and shift operators with truth tables, a live calculator and masking patterns
Blood Type Compatibility Reference
ABO and Rh compatibility for transfusion and donation
Bluetooth Version Reference
Bluetooth 1.0 through 5.4 range, speed, and features
BMI Classification Reference
WHO BMI categories from underweight to obese with ranges
Bolt Grade & Strength Reference
Tensile and yield strength for metric and imperial bolt grades
BOM Byte-Order Mark Reference
Byte-order marks for UTF-8, UTF-16, UTF-32 with hex sequences and platform notes.
Braille Reference Chart
Grade 1 Braille cell patterns for letters, numbers, and punctuation
C Standard Library Reference
POSIX and C99 standard library functions searchable by header and name.
Calendar System Reference
Gregorian, Julian, Hebrew, Islamic, and other calendar systems
Food Calorie Density Reference
Calories per 100g for 150+ common foods
Canadian Province & Territory Reference
All 10 provinces and 3 territories with codes and capitals
Carton & Board Weight Reference
GSM ranges for paper, card and board with typical applications.
Central Bank Interest Rate Reference
Current policy rates for the world's major central banks
Character Set (Charset) Reference
IANA registered charset names and aliases with encoding spec and common use.
Clothing Care Symbol Reference
Decode all GINETEX laundry care symbols on garment labels.
Cloud Classification Reference
All 10 cloud genera with altitude, appearance and weather association.
Cloud Region Reference
AWS, GCP and Azure region codes with geographic locations.
Genetic Codon Table Reference
All 64 RNA codons and the amino acids they encode
COEP / CORP / COOP Headers Reference
Cross-Origin Embedder, Resource, Opener Policy headers with isolation model.
Coffee Roast Level Reference
Light, medium, dark, and espresso roasts with Agtron numbers.
Commodity Trading Unit Reference
Standard contract units for oil, gold, wheat, and other commodities
Content-Security-Policy Reference
Every CSP directive with source-list syntax, fetch vs document vs navigation types.
Continent & Region Reference
Browse countries grouped by continent and UN subregion.
Control Characters Reference
ASCII control characters 0–31 with names, abbreviations and historic uses.
HTTP Cookie Attributes Reference
All Set-Cookie attributes — Domain, Path, Expires, HttpOnly, SameSite, Partitioned.
Cooking Temperature Reference
Safe internal temperatures for meats, poultry, and baked goods
CORS Headers Reference
Every CORS request and response header with preflight flow and misconfig notes
CORS Preflight Request Reference
OPTIONS preflight request/response header flow with wildcard and credential rules.
Country Area Reference
Total area for the world's countries in km² and square miles
Birth Rate by Country Reference
Crude birth rates per 1,000 population for countries worldwide
ISO 3166-1 Country Codes
All ISO 3166-1 alpha-2, alpha-3, numeric codes with country name and region.
Cybersecurity Law by Country Reference
Key data protection and cybersecurity legislation by country.
National Debt as % of GDP by Country
Government debt-to-GDP ratios for countries worldwide
Emergency Phone Number by Country Reference
Police, fire and ambulance numbers by country
Country GDP Reference
Nominal GDP and GDP per capita for major economies
Gini Coefficient by Country Reference
Income inequality Gini index for all countries
Human Development Index Reference
UNDP HDI scores and Very High / High / Medium / Low tiers
Head of State Title by Country
Is it President, Prime Minister, King, or Sultan by country?
Country Independence Date Reference
When did every country gain independence, and from whom?
Literacy Rate by Country Reference
Adult literacy rates for major countries with gender breakdown.
National Animal by Country Reference
The official national animal symbol for every country
Traditional Numeral Systems Reference
Arabic, Eastern Arabic, Devanagari, Thai, Bengali and more digits.
Official Language by Country Reference
Official and co-official languages for the world's countries
Country Population Reference
Latest UN population estimates for the world's largest countries
Predominant Religion by Country Reference
The majority religion for each country with an approximate share
Unemployment Rate by Country Reference
Latest ILO-harmonised unemployment rates for countries worldwide
CPT Code Section Reference
Browse CPT code sections: E&M, Surgery, Radiology, Pathology
CPU Socket Reference
Intel and AMD desktop CPU sockets with compatible CPUs.
Creative Commons License Reference
All 7 CC licenses with permissions and conditions.
Cron Expression Reference
Decode and compose cron expressions with field-by-field reference and examples.
Top Cryptocurrency Ticker Reference
Tickers and full names for major cryptocurrencies
curl Flags Reference
Search every curl option flag with description, short form and usage examples
ISO 4217 Currency Codes
All ISO 4217 currency codes with name, numeric code, minor unit and country.
Currency Symbol Reference
Find the correct symbol for any currency worldwide
Customs Procedure Code Reference
UK and EU customs procedure codes for import and export declarations.
CVSS Score Reference
CVSS v3.1 severity ratings: None, Low, Medium, High, Critical.
Cypress Commands Reference
All Cypress cy.* commands with argument types, subject chaining and aliases.
Data Structure Complexity Reference
Insert, delete, search complexity for arrays, trees, graphs and heaps.
Decibel (dB) Reference Table
Real-world sound levels mapped to decibel values and safe-exposure limits
Depreciation Method Reference
Straight-line, declining balance, sum-of-years-digits explained with a live schedule.