Guides
Short how-tos and explanations. Each one links to the tool that does the job in your browser, with no uploads.
How to Merge PDFs Into One File
Combine several PDF files into one document in your browser, with tips on page order, protected files and file size.
How to Compress a PDF (and What to Expect)
Why PDFs get large, what browser-based compression can and cannot do, and how to choose between light and maximum modes.
How to Convert JPG Images to a PDF
Turn photos or scans in JPG, PNG or WebP format into one PDF, with advice on page order, page size and file size.
How to Split a PDF by Page Range
Extract pages or cut a PDF into several files using page ranges like 1-3,5,7-9.
How to Annotate, Sign and Organize a PDF
A practical guide to adding notes and signatures to a PDF, rearranging pages, and understanding what browser editing can change.
Marketing
How to Generate a QR Code for a Link, Wi-Fi or Contact
Create a QR code for a website, Wi-Fi login or contact card, and learn how to make sure it scans reliably.
How to Build UTM Links for Campaign Tracking
What UTM parameters are, which ones are required, and naming habits that keep your analytics reports clean.
Images
How to Convert HEIC Photos to JPG
What HEIC files are, why they sometimes will not open, and how to convert them to widely supported JPG.
How to Edit an Image Online: Crop, Draw and Add Layers
Use a browser image editor to crop a photo, add text or shapes, draw, arrange image layers, and export a copy.
How to Resize and Compress Images for the Web
Reduce image dimensions and file size while choosing a format and quality that still looks good on a website or in a message.
How to Convert an SVG to PNG
Convert a vector SVG into a PNG at the pixel dimensions you need, and learn what can change during raster export.
Money
What Is Compound Interest?
A plain explanation of compound interest with worked examples, the rule of 72, and how to project your own savings.
How to Calculate VAT (DPH) in the Czech Republic
Add VAT to a price or take it out of a total, using the Czech 21% and 12% rates, with worked examples.
How to Calculate a Percentage Discount
Find the sale price, the amount saved, and the original price from a discounted one, including stacked discounts.
How to Calculate Profit Margin and Markup
The difference between margin and markup, with a worked example and how to price for a target margin.