工具指南与教程
清晰的分步文章，教你压缩图片、处理 PDF、格式化代码并节省时间 — 全部使用浏览器中运行的免费工具。
精选指南
How to Compress Images Without Losing Quality
Large images slow down websites and blow past upload limits. Learn why image files get big, how far you can safely compress, and how to shrink JPG, PNG and WebP files so the difference stays invisible.
How to Merge PDF Files for Free
Join contracts, scans and reports into a single PDF — in the right order, without uploading anything. A step-by-step guide plus the follow-up steps most people forget.
How to Format JSON Online: A Beginner's Guide
Minified JSON is unreadable. Format it with proper indentation, validate it in the same click, and learn the five errors that break almost every JSON file.
全部指南
Best Free AI Tools for Students: A Practical Guide
AI can draft, explain, quiz and organise — but only if you stay in charge. A practical, hype-free guide to the free AI tools that genuinely help students.
How to Create a QR Code for Free
From CVs to café menus, QR codes connect paper to the web. Generate a crisp PNG in seconds and learn the design rules that keep it scannable.
10 Practical Ways to Save Time With Free Online Tools
Small chores eat hours every month. Here are ten specific, practical ways to hand them to free browser tools — with links to each tool.
How to Calculate Reading Time for an Article
A 5-minute read label is a promise to the reader. Learn the simple math behind reading time, which speed to assume, and how to calculate it accurately.
How to Count Words and Characters Online
Essay limits, meta descriptions, ad copy — every format has a number attached. Paste your text into a free counter and hit the target on the first try.
How to Convert Images to PDF
Applications want one PDF; your camera produces JPEGs. Convert a set of images into a properly paginated PDF in a few clicks — A4 or Letter, nothing uploaded.
How to Decode Base64 Safely
Base64 is everywhere — emails, tokens, data URIs. Learn what it does and does not do, how to spot it, and how to decode it safely in one step.
How to Add a Watermark to an Image
Mark your photos and documents with a clear, tasteful watermark. Learn where to place it, how strong to make it, and how to export a watermarked image in seconds.
How to Add Page Numbers to a PDF
Unnumbered PDFs are miserable to cite and to print. Number every page in seconds, with control over position, alignment and where the count starts.
How to Convert JSON to CSV
Turn JSON arrays into spreadsheet-ready CSV in your browser — columns from all keys, values correctly quoted, and a safe path into Excel or Google Sheets.
How to Resize an Image Without Stretching It
Squashed faces and distorted logos happen when width and height are changed independently. Learn the aspect-ratio rule, the exact resize workflow, and when cropping is the better choice.
How to Extract Specific Pages From a PDF
Send only the two pages that matter, split a long report, or pull out a signed page — with visual page selection and no software to install.
How to Convert CSV to Excel Without Losing Data
Opening a CSV directly in Excel can silently mangle phone numbers, IDs and dates. Convert it properly instead and keep every value exactly as written.
How to Convert HEIC Photos to JPG or PNG
HEIC photos look perfect on an iPhone but fail everywhere else. Learn what the format is, when to pick JPG or PNG, and how to convert your files in a few clicks.
How to Rotate PDF Pages Online
Scans and phone photos often land sideways inside PDFs. Rotate all pages or just a page range in a few clicks, then renumber and recombine the document.
JSON vs XML: What's the Difference?
JSON and XML both structure data, but they reward different jobs. See the same data in both formats, compare their features, and learn when to reach for which.
WebP vs PNG vs JPG: Which Image Format Should You Use?
JPG, PNG and WebP each solve a different problem. Compare the three formats side by side and learn which one to pick for photos, logos, screenshots and modern websites.
How to Format JSON Online: A Beginner's Guide
Minified JSON is unreadable. Format it with proper indentation, validate it in the same click, and learn the five errors that break almost every JSON file.
How to Compress Images Without Losing Quality
Large images slow down websites and blow past upload limits. Learn why image files get big, how far you can safely compress, and how to shrink JPG, PNG and WebP files so the difference stays invisible.
How to Merge PDF Files for Free
Join contracts, scans and reports into a single PDF — in the right order, without uploading anything. A step-by-step guide plus the follow-up steps most people forget.