精选工具合集
按主题人工精选的工具合集——每个合集都是一篇带点评的推荐清单，帮你快速找到顺手的工具。
精选 8 个高频在线计算器：百分比、年龄、BMI、日期间隔、折扣、复利、房贷与睡眠周期，即开即算，附公式说明。
精选 10 个高频文本工具：大小写转换、摩斯密码、花体字生成、Lorem Ipsum、字数统计、slug 生成、文本对比与字符计数，粘贴即用。
精选 8 个时间与日期工具：日期间隔、工作日天数（含节假日调休）、农历转换、倒计时秒表、睡眠周期、年龄计算等，覆盖日程规划高频需求。
精选 13 个高频 PDF 工具：合并、转图片/TXT/Markdown/Excel/HTML/长图、图片与 Office 转 PDF、页面调整，一站式处理。
精选 13 个高频图片工具：压缩、格式转换、自定义尺寸、Favicon 生成、加/去水印、PNG 转 SVG、GIF 拆分、视频转 GIF、拼图、证件照排版等。
精选 22 个开发者高频工具：JSON/SQL 格式化、Base64、URL 编解码、JWT 解码、哈希、正则、Cron、时间戳、UUID/密码/随机数生成、二进制转换、px/rem 换算、Meta 与 robots.txt 生成等。
精选 9 个健康类计算器：BMI、孕周/预产期/排卵、年龄、睡眠周期、咖啡因代谢、睡前饮水窗口与食物热量查询。
精选 10 个装修家居计算器：瓷砖、油漆、壁纸、地板、窗帘、美缝、灯光、开关插座布局、电费与空气炸锅换算。
精选 18 个理财与经营计算器：个税、年终奖、公积金组合贷、房贷、贷款、小费分摊、复利、投放 ROI、退休规划、租房成本、FIRE 倒计时、折扣、百分比、大写金额、电商利润、SaaS 指标与副业时薪。
精选 7 个日常生活高频工具：亲戚称呼计算、身份证号校验、公历农历互转、工作日天数、年龄计算、金额大写与汉字转拼音。
卖卡密、资料包、课程类虚拟商品的 7 个配套工具：定价计算器、标题优化、合规检查、发货话术、售后回复、人设生成与全流程导航。
English collections
The most-used free online calculators in one place: percentage, age, BMI, date, discount, compound interest, mortgage and sleep cycle — with formulas.
Free text tools in one place: title case, word and character counters, case converter, text diff, repetition checker, slug generator, Morse code and fancy text.
The most useful date and time tools in one place: days-between-dates, countdown and stopwatch, sleep cycle planner, exact age and more.
The PDF tools people search for most: merge, PDF to image/TXT/Excel/HTML, image and Office to PDF, and page adjusting — no software to install.
The dev utilities people search for most: JSON and SQL formatters, JWT decoder, Base64, hash, regex, UUID and password generators, cURL-to-code, Mermaid and more.
The renovation calculators people search for most: tiles, paint, wallpaper, flooring, curtains, lighting lumens, electricity cost and air fryer conversion.
The money calculators people search for most: mortgage with taxes, loan amortization, tip splitting, compound interest, ROI, rent costs and discounts.
The image tools people search for most: compressor, format converter, favicon generator, PNG to SVG, GIF splitter, video to GIF and color picker.
The health calculators people search for most: BMI, due date, pregnancy week, ovulation, exact age, sleep cycles, caffeine and food calories.