PDFガイドとヒント
PDF作業の実用的なガイド — 結合、分割、圧縮、変換、トラブル解決。
How to OCR a PDF for Free — Extract Text from Scanned Documents
Scanned PDFs look like normal documents, but you can't select, search, or copy any of the text. OCR fixes that by reading the image and extracting the text — and you can do it for free without uploading your file anywhere.
How to Sign a PDF Online for Free (Draw, Type, or Upload Your Signature)
You shouldn't need to print a document, sign it with a pen, scan it back in, and email the scan — just to put your name on a PDF. Here's how to sign a PDF online for free, directly in your browser.
What Are PDF Vulnerabilities and How Can You Scan For Them?
PDFs are the universal standard for sharing documents, but they can be surprisingly dangerous. Discover how malicious PDFs operate and how to scan them safely.
Browser-Based vs Desktop PDF Tools: Pros, Cons & When to Use Each
Desktop PDF tools like Adobe Acrobat are powerful but costly. Browser-based tools are free and instant. Here is when to use each.
How to Combine Multiple Invoices Into One PDF
Combine monthly invoices, quarterly reports, or batch invoices into one organized PDF for clients and accountants.
How to Compress a PDF to Send by Email (Under 10MB)
Compress PDFs for email by reducing image quality and removing metadata. Most email providers limit attachments to 20-25MB.
How to Convert JPG Images to PDF on iPhone
Turn photos taken on your iPhone into a single PDF document.
How to Create One PDF from Multiple Images (JPG, PNG, or Both)
Turn multiple photos and images into one PDF. Works with JPG, PNG, or a mix of both formats.
How to Extract Specific Pages from a PDF
Extract a single page, a range of pages, or multiple non-consecutive pages from a PDF document.
How to Merge PDF Files on Android Without Downloading Anything
Merge PDF files on Android directly in Chrome without downloading an app or uploading your files.
How to Merge PDF Files on a Chromebook (Free & Browser-Based)
Chromebooks cannot run desktop apps, making browser-based PDF merging the only practical solution.
How to Merge PDF Files on iPhone (No App, No Upload)
Merge PDF files on your iPhone using Safari without downloading an app or uploading to any server.
How to Merge PDF Files on Mac for Free (No Software Download)
Merge PDF files on your Mac using Preview or a browser-based tool. Both are free and require no downloads.
How to Merge PDFs Without Uploading Them to Any Server
Merge PDFs locally in your browser without uploading to servers. The most private way to merge documents.
How to Reduce PDF File Size Without Losing Quality
Not all PDFs compress equally. Image-heavy PDFs shrink 50%+. Text-only PDFs barely shrink. Know the difference.
How to Remove a PDF Password Without Installing Software
Remove PDF passwords to unlock editing and printing. Browser-based, password never leaves your device.
How to Permanently Rotate a PDF Page (So It Stays Rotated)
Permanently rotate PDF pages so they stay rotated when you reopen the file. Not just a view change.
Is It Safe to Upload PDF Files to Online Tools?
Understanding server-based vs browser-based PDF tools helps you decide which tools are safe for sensitive documents.
PDF vs DOCX: Which Format Should You Send?
Send PDF when the document is final. Send DOCX when the recipient needs to edit it. Here is the full decision guide.
What is a HEIC File? (iPhone Photos Explained)
iPhones use HEIC format for better quality at smaller file sizes. Learn why and how to convert it.
What is a JPG File and When Should You Use It?
JPG is the most common image format on the web. Learn the secrets of image compression and when to convert your photos into PDFs.
What is a PDF File and When Should You Use It?
Portable Document Format is the global standard for sharing documents. Discover what makes PDFs unique and when you should use them over editable formats.
What is a PNG File and When Should You Use It?
PNGs save every single pixel perfectly, making them the best format for screenshots, graphics, and text. Here is how and when to use them.
What is a TIFF File and When Should You Use It?
TIFF files are lossless, high-quality images used in professional photography, printing, and archiving. Learn when to use them.
What is a Word Document and When Should You Use It?
Microsoft Word files (DOCX) are the kings of editable text. Find out why they are perfect for drafting, and why you should convert them before sharing.
What is an RTF File and How Does It Compare to DOCX and PDF?
RTF is a text format that predates DOCX. Learn what RTF files are, why they persist, and when to use them.
What is a Markdown File (.md) and When Should You Use It?
Markdown is a deceptively simple text format that lets you write quickly without touching your mouse. Learn the basics, its history, and how to share your notes.
How to Convert Markdown Files to PDF
Markdown is great for writing, but terrible for sharing with non-technical people. Here's how to convert your .md files into clean, readable PDFs without uploading sensitive data to a random server.
How to Remove a Password from a PDF You Already Own
This is for removing passwords from PDFs where you already know the password. Not a cracking tool — you need the password. But if you're tired of typing it every time, or need to merge a locked PDF with others, this is how to do it.
How to Convert a Word Document to PDF
This is the most common document conversion people need, and usually it's straightforward. But there are a few specific things that trip people up — especially around fonts and wide tables.
How to Convert a PDF to an Editable Word Document
Honest upfront: PDF-to-Word conversion is never perfect. PDF is a fixed format — it wasn't designed to be edited. But for most common documents, the result is good enough to save you hours of retyping.
How to Convert a PDF Page to a JPG or PNG Image
Sometimes you need a PDF page as an image — for a presentation, a website thumbnail, or a system that accepts images but not PDFs. Here's how to do it.
How to Combine Photos and Images Into a Single PDF
You have a bunch of photos — scanned receipts, whiteboard photos, handwritten notes — and need to send them as a single document. Sharing 15 separate JPGs is a mess. A PDF is much cleaner.
How to Delete Pages from a PDF
You have a 30-page PDF but only need to send 25 of them. Maybe the last pages are blank, or the first is a cover sheet you don't want to include. Here's the fastest way.
How to Compress PDF Without Losing Quality
A PDF that is 50MB when it should be 2MB is a genuine nuisance. Learn how PDF compression works and how to shrink your files without ruining them.
How to Fix PDF Page Rotation
Scanned documents are notorious for being upside down or sideways. Learn why this happens and how to permanently rotate your pages back to normal.
How to Split a PDF and Extract Exactly the Pages You Need
Someone sends you a 40-page PDF and you only need pages 3 through 7. Here's how to securely extract those pages without paying for premium software.
How to Merge PDF Files for Free (No Sign Up, No Catches)
The number of "free" PDF tools that hit you with a paywall after you've already uploaded your files is genuinely maddening. Here's how to actually do it for free.