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 4 of 5.
REST Architectural Constraints
All six REST constraints from Fielding's dissertation with definition and the implication each one has
Richter & Mercalli Scale Reference
Earthquake magnitude and intensity scales with effects and an energy estimate.
World Rivers Length Reference
The longest rivers with length, source, and outflow
Legal Latin Terms Reference
Common Latin legal terms with plain-English definitions
Ancient Roman Road Reference
Major Roman roads with Latin name, route, and length
Royal and Noble Title Reference
King, Duke, Marquess, Earl — title hierarchy by country
Airport Runway Marking Reference
Runway designators, thresholds, touchdown zones, and aiming points explained.
Rust Error Reference
Search Rust standard-library error types, traits and common crate error variants.
Rust Standard Traits Reference
Key Rust std traits with required methods, blanket impls and derive support.
Saffir-Simpson Hurricane Scale Reference
Hurricane Categories 1 to 5 with sustained wind speeds and typical surge.
SameSite Cookie Attribute Reference
SameSite=None/Lax/Strict behavior with cross-origin request type matrix.
Douglas Sea State Reference
Douglas scale sea state codes with wave heights and descriptions.
HTTP Security Headers Reference
HSTS, CSP, X-Frame-Options and every security header with recommended values
sed Commands Reference
All sed commands, addresses and flags with examples for stream editing.
Semaphore Flag Alphabet Reference
All semaphore flag positions for the Latin alphabet
Semiconductor Process Node Reference
Chip process nodes from 90nm to 2nm with maker timeline.
Semantic Versioning Reference
SemVer 2.0 rules, npm range operators and pre-release precedence explained
Service Worker Events Reference
All service worker lifecycle and functional event types with timing and scope.
Sheet Metal Gauge Reference
Convert gauge numbers to thickness for steel, aluminium, and copper
SI Base Units Reference
The 7 SI base units with full definitions and symbols
SI Derived Units Reference
Named SI derived units like hertz, newton, pascal, and joule
Engineering Unit Prefix Reference
Metric prefixes with engineering notation equivalents
SIP Response Codes Reference
All SIP 1xx-6xx response codes with RFC source and telephony context.
SMTP Reply Codes Reference
All SMTP 2xx/3xx/4xx/5xx reply codes with meaning and enhanced status codes.
Open Source License Compatibility Reference
Which OSS licences are compatible for linking and distribution
Open Source License Reference
Permissive vs copyleft OSS licenses and their obligations.
SOLID Principles Reference
SOLID, DRY, KISS, YAGNI and more — each principle's definition, the anti-pattern it prevents, and its code smell
Solubility Rules Reference
Quick solubility rules for common ionic compounds in water
Sorting Algorithm Reference
Compare quicksort, mergesort, heapsort and more side by side.
Source Map v3 Fields Reference
All source map JSON fields — mappings, sources, names, sourceRoot — with VLQ notes.
Specific Heat Capacity Reference
Cp values for solids, liquids, and gases at standard conditions
Default Speed Limit by Country Reference
Urban, rural, and motorway speed limits for countries worldwide
Spirits ABV Reference
Typical ABV ranges for whisky, vodka, gin, rum, and tequila.
SSH Cipher Suite Reference
Recommended and deprecated SSH ciphers, MACs, and key exchange.
SSH Config Options Reference
Every ~/.ssh/config keyword with type, scope and connection behavior.
Steel Alloy Grade Reference
Cross-reference AISI, EN, DIN, and JIS steel grades
Major Stock Index Reference
Key global stock indices with exchange, country, and components
Storage Interface Reference
SATA, NVMe, M.2, PCIe generations with throughput
Subresource Integrity (SRI) Reference
SRI integrity attribute format with hash algorithm options and crossorigin notes.
SVG Presentation Attributes
Every SVG presentation attribute with its CSS equivalent and what it applies to
SVG Elements Reference
All SVG 2 elements with category, content model and what they render
Symmetric Cipher Reference
AES, ChaCha20, 3DES ciphers with key sizes, modes and security recommendations.
systemd Specifiers Reference
All systemd unit file specifiers (%n, %h, %u…) with resolved value descriptions.
systemd Unit Options Reference
Key systemd [Unit], [Service], [Socket], [Timer] options with type and default.
UK/US Tax Treaty Reference
Key withholding rates under major bilateral tax treaties, with a partner filter.
TCP/UDP Well-Known Port Reference
Find the service assigned to any well-known port 0–1023
tcpdump BPF Filter Reference
tcpdump BPF filter expressions — host, port, proto, flags — with combination logic.
Temperature Reference Points
Key temperature landmarks in Celsius, Fahrenheit, and Kelvin
Terraform Built-in Functions
Search Terraform built-in functions by name, category and signature.
Thermal Conductivity Reference
Heat conductivity values for metals, polymers, and building materials
Tidal Classification Reference
Spring, neap, and mixed tides explained with examples
Time Zone Abbreviation Reference
Decode ambiguous time zone abbreviations like EST, CST, IST
IANA Time Zone Identifiers
Search IANA tz database identifiers by name, country or UTC offset.
Timezone Reference Lookup
Find IANA timezone identifiers for any city or country
Top-Level Domain Reference
Browse TLDs: generic, country-code, sponsored, and new gTLDs
TLS Cipher Suite Reference
TLS 1.2 and 1.3 cipher suites with security rating.
TLS Cipher Suite Reference
Browse TLS 1.2 and 1.3 cipher suites with security rating and key exchange.
Transfer-Encoding Reference
chunked, gzip, deflate, br transfer-encoding values with combination rules.
Trigonometric Values Reference
sin, cos, tan values at 0, 30, 45, 60, 90 degrees and key angles.
Twilio Error Codes Reference
Twilio error and warning codes by product — Voice, SMS, Video, Auth.
Two's Complement Reference
Encode and decode signed integers in two's complement with a live 8/16/32/64-bit calculator and range table
TypeScript Compiler Flags Reference
All tsc CLI flags with effect, default and tsconfig.json equivalent.
TypeScript Utility Types Reference
All TypeScript built-in utility types with signature, effect and example usage.
Tyre Size Designation Reference
Decode any tyre sidewall code: 225/45R17 explained.
UN Hazmat Class Reference
All 9 UN dangerous goods classes with labels and examples
UN Member State Reference
All 193 UN member states with admission year and region.
Unicode Block Reference
Browse Unicode blocks and their code-point ranges
Data Storage Unit Reference
Bytes, KB, MB, GB, TB — SI (1000) vs binary (1024).
Unix Signals Reference
Look up POSIX and Linux signals by name or number with default disposition.
USB Standard Reference
USB versions 1.0 through 4.0 with speed and connector types
UTC Offset Reference
See which countries observe each UTC offset right now
UV Index Reference Table
WHO UV Index 0 to 11+ with exposure categories and sun-protection advice.
Vapor Pressure Reference Table
Saturation vapor pressures for water and common solvents
HTTP Vary Header Reference
HTTP Vary header usage with CDN caching implications and common field names.
Visa-on-Arrival Reference by Passport
Countries offering visa on arrival to major passport holders
Visible Light Wavelength Reference
Wavelengths and frequencies for each colour of visible light
WebAssembly Import/Export Reference
Wasm import and export descriptor types — func, table, memory, global — with syntax.
WebAssembly Instruction Reference
Core WebAssembly instructions by type — numeric, memory, control and parametric.
WebAssembly Value Types Reference
Wasm i32, i64, f32, f64, v128, funcref, externref types with encoding
Watch Movement Reference
Ebauche calibre numbers for major Swiss and Japanese movements.
Water Hardness Classification Reference
Soft to very hard water thresholds in mg/L, grains per gallon and degrees dH.
Browser Web APIs Quick Reference
Search browser global APIs — fetch, Storage, IndexedDB, Workers, Canvas and more
Web Crypto API Algorithms Reference
All Web Crypto SubtleCrypto algorithm names with operation support matrix.
Web Storage API Reference
localStorage and sessionStorage methods with quota limits and storage-event properties.
Web Vitals Thresholds Reference
Core and experimental Web Vitals thresholds — Good, Needs Improvement, Poor
WebSocket Subprotocol Reference
IANA-registered WebSocket Sec-WebSocket-Protocol subprotocol names with description.
Week Number System Reference
ISO 8601 vs US week numbering: differences by country
Well-Known URIs Reference
All IANA-registered /.well-known/ URI paths with application and spec link.
Wi-Fi Standard Reference
802.11a/b/g/n/ac/ax/be speeds and frequency bands
Wind Direction & Compass Reference
All 32 compass points with their degrees, plus a bearing-to-heading converter.
WireGuard Config Reference
WireGuard [Interface] and [Peer] config keys with type and wg-quick extensions.
World Bank Income Group Reference
Low, lower-middle, upper-middle, and high income thresholds explained
World Cities Population Reference
Population of the largest cities worldwide, ranked
UNESCO World Heritage Category Reference
Cultural, natural, and mixed site criteria (i–x) explained
Nuclear Reactor Type Reference
PWR, BWR, CANDU, and other reactor types compared.
Writing System Reference
Latin, Cyrillic, Arabic, Devanagari, CJK and more, by type.
X.509 OID Reference
Look up X.509 certificate OIDs by dotted notation or attribute name.
XPath Reference
XPath 1.0 and 2.0 axes, functions and expressions in a searchable table
Young's Modulus Reference Table
Elastic modulus, shear modulus, and Poisson's ratio for materials
HTTP Status Codes Reference
Every HTTP status code with its meaning — searchable and instant.