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ステップバイステップのガイドで、オンラインツールを効果的に使う方法を学べます。

How to Format and Validate JSON Online (Complete Guide)

Format, beautify and validate JSON online free. Fix common errors like trailing commas and unquoted keys, and convert JSON — private, in-browser.

Convert JPG images to PDF online free. Combine multiple photos into one document, set page size and order, and keep quality — private, no signup.

Create strong, memorable passwords using the passphrase method. Learn length and complexity rules, what to avoid, and generate secure passwords free.

Calculate BMI correctly with the metric and imperial formulas. See WHO categories, healthy ranges by age, limitations, and free calculator tips.

Count words and characters online free. Check reading time, platform limits for Twitter, Instagram and LinkedIn, and hit your target fast.

Create QR codes free for URLs, WiFi, contacts and more. Customize colors and logo, pick error correction, and download PNG or SVG — no signup.

Resize images for Instagram free with the correct 2026 sizes for posts, stories and reels. Avoid cropping and blur — fast, private, in-browser.

Convert PDF to editable Word free. Extract text from PDFs, handle scanned files with OCR, and keep formatting — private, in-browser, no signup.

Merge multiple PDF files into one online free. Combine up to 20 PDFs, reorder pages by drag and drop, 100% private — no signup or upload.

Compress PDF files online free without losing quality. Learn the best compression levels, how much you can shrink files, and privacy-safe tips.