Free Online Quick Lookup Tools

Free online material density lookup tool, provides density data for various materials including metals, non-metals, liquids, and gases. Supports multi-unit switching, an essential material reference tool for engineers and researchers.

Free online tool for searching national and regional flags worldwide, provides high-resolution flag images for viewing and download. Supports filtering by region, flag type, and search queries, includes detailed flag information such as adoption year, aspect ratio, color composition, and more.

Free online China region information lookup tool, supports five-level administrative division queries from province to village, includes complete region information such as postal code, telephone area code, ID card prefix, license plate prefix, etc. Real-time query, accurate data, no download required, suitable for address filling, information verification, data analysis and other scenarios.

Free online interactive periodic table of elements, contains detailed information of 118 chemical elements, supports classification filtering and search query, click to view element properties, electron configuration, physical properties and other detailed data. Suitable for chemistry learning, teaching demonstration and research reference.

Free online public DNS server query tool, provides addresses of major DNS servers worldwide, response speed test, one-click copy and other features. Supports popular DNS services such as 114 DNS, Alibaba Cloud DNS, Tencent Cloud DNS, Google DNS, Cloudflare DNS and more.

Free online tool for querying currency codes, currency symbols and currency names of countries worldwide, supports ISO 4217 standard currency code retrieval, includes information on 180+ global currencies such as USD, EUR, JPY, GBP, CNY and more. Suitable for cross-border payments, foreign exchange trading, international trade and other scenarios.

Free online browser User-Agent lookup tool, automatically detects and parses browser type, version, operating system, device model and other information. Supports simulated browser UA generation, suitable for frontend development debugging, device compatibility testing and other scenarios.

Free online font license lookup tool, supports querying license types, commercial usage rights, and free commercial font recommendations for Chinese and English fonts, helping designers and developers avoid font infringement risks.

Online world standard time query tool, displays real-time current time, timezone and daylight saving time information for 200+ countries/regions. Supports city search and time difference calculation, suitable for cross-border meetings, international trade communication and other scenarios, with accurate automatically updated data.

Free online search engine UserAgent collection, includes UserAgent strings of major search engine crawlers such as Google, Baidu, Bing, Yahoo, 360, Sogou, Shenma and more, supports one-click copy, convenient for website log analysis and crawler identification.

Free online batch ID card number verification tool, supports validation of 18-digit Chinese ID card numbers, region lookup, date of birth extraction, gender identification and other functions. Suitable for member information review, personnel file organization, e-commerce real-name authentication and other scenarios.

Complete command reference for Claude Code AI programming assistant, including all built-in tools and shortcuts for file operations, code search, command execution, task management, web search, and browser automation.

Free online zodiac and constellation query tool, supporting 12 Chinese zodiac signs and 12 Western constellations with detailed personality traits, compatibility suggestions, and lucky guides.

Free online Chinese idiom query tool supporting fuzzy search, position search, pinyin search, and meaning search. Contains 29500+ common idioms to help you find what you need quickly.

A must-have tool for developers and DevOps engineers to find fast open source mirrors in China. Indexes mainstream mirrors like Alibaba Cloud, Tencent Cloud, and USTC. Supports one-click lookup and replacement for Linux system sources (CentOS, Ubuntu, Debian) and development environments like Maven, NPM, PyPI, and Docker Hub.

Professional door and window performance parameter calculation and education tool. Supports K-value/U-value conversion, sound insulation calculation, air tightness rating assessment, water tightness analysis, wind load calculation, and more.

Free online AI open source LLM quick reference tool. Supports comparison of mainstream open source models including GPT, Claude, Llama, Gemini, Qwen, DeepSeek, etc. Contains detailed information on model capabilities, context length, pricing, release dates, helping developers quickly choose the right AI model.

Free online lens power thickness estimation tool supporting myopia and hyperopia lens thickness estimation. Input diopter, refractive index, lens diameter and other parameters to accurately estimate center thickness and edge thickness, with thickness evaluation, cross-section visualization and refractive index comparison analysis.

Free online lens prescription conversion tool supporting frame glasses to contact lenses conversion, astigmatism conversion, and base curve reference. Based on vertex distance formula, automatic precise conversion for prescriptions over 400 degrees.

Free online dog cost calculator. Calculate daily food intake, water consumption, and feeding costs based on your dog's weight, age, and activity level. Plan your pet budget scientifically.

Free online cat cost calculator. Calculate daily food intake, water consumption, and feeding costs based on your cat's weight, age, and activity level. Supports dry food, wet food, and mixed feeding methods.

A professional online tool for accurate CAD meter weight calculation, suitable for engineering, machinery and other scenarios. Enter CAD related parameters to automatically calculate meter weight accurately, no installation or registration required.

Free online mortgage calculator supporting commercial loans, provident fund loans, and combined loans. Calculate monthly payments, total interest, and repayment schedules with equal principal & interest or equal principal repayment methods.

Free online Linux command reference covering file operations, text processing, system information, network tools, process management, package management, user management, and disk management with syntax, options, and examples.

Free online open source license reference tool covering 24 major licenses including MIT, Apache 2.0, GPL, AGPL, LGPL, BSD, MPL, PostgreSQL, Zlib, EUPL and more. Detailed information on license types, permissions, conditions and limitations to help developers choose the right open source license.

Free online keyboard shortcut reference tool. Comprehensive collection of Windows and macOS system shortcuts with search and category browsing. Covers general operations, navigation, text editing, system functions, screenshots, virtual desktop, and more.

Global emergency contact number lookup tool. Search by country/region for police, ambulance, fire and other emergency contact numbers. Essential reference for overseas travel, study, and business trips.

Free online national anthems player. Browse and listen to national anthems from countries around the world, organized by continent with quick search functionality.

Free online Docker command cheatsheet covering container management, image operations, volumes, networks, Docker Compose and more. Features search filtering and one-click copy for quick developer reference.

Free online standard carton size calculator. Enter item length, width, height and quantity to get recommended inner/outer box dimensions, volume utilization, and stacking layout. Supports custom board thickness, clearance, and reverse calculation for a given box.

Free online tool to query historical events, famous births, deaths, and holidays that occurred on this day. Multilingual support with data from Wikipedia.