Guides to our free online tools
Short, practical guides that explain what each tool does, how to use it step by step, and how to avoid the common mistakes.
Every tool on CPV Technologies runs inside your browser, so your photos, PDFs and text stay on your device. These guides go further than a button label: they explain the ideas behind each tool, such as why a PNG cannot be compressed like a JPEG, how an EMI is calculated or what 413 x 531 pixels means for a passport photo, and they include worked examples you can check by hand.
Pick a topic below, read the guide, then open the tool. Everything is free and needs no sign-up.
Image tools
Resize, compress, convert and prepare photos for forms, websites and print.
Image Compressor
Learn how to reduce the file size of JPG, PNG and WebP photos in your browser without uploading them, and how to choose the right quality setting.
Read the guide · Open the toolImage Resizer
A practical guide to resizing photos to exact pixel dimensions in your browser, including aspect ratio, enlarging and the right size for web and forms.
Read the guide · Open the toolImage Converter
Convert images between JPG, PNG and WebP in your browser.
Read the guide · Open the toolImage Cropper
How to crop an image to exact pixel coordinates in your browser, with a simple method for choosing X, Y, width and height.
Read the guide · Open the toolPassport Photo Resizer
Resize a photo for passport, visa and ID applications.
Read the guide · Open the toolSignature Resizer
Prepare a scanned signature for online forms: resize to exact pixels, choose PNG or JPEG, and keep the file size small.
Read the guide · Open the toolFavicon & App Icon Generator
Create favicon and app icon PNG files in 16, 32, 48, 180, 192 and 512 pixel sizes from any logo, and learn how to add them to your website.
Read the guide · Open the toolPhoto Dimensions Converter
Convert photo sizes between pixels, millimetres, centimetres and inches at any DPI.
Read the guide · Open the toolImage to PDF
Combine one or more photos or scans into a single PDF in your browser.
Read the guide · Open the toolPDF tools
Merge, split, rotate, number and inspect PDF files without uploading them.
PDF Merger
Merge several PDF files into one document in your browser without uploading them.
Read the guide · Open the toolPDF Page Rotator
Fix sideways or upside-down PDF pages by rotating all pages or only selected ones, 90, 180 or 270 degrees, directly in your browser.
Read the guide · Open the toolPDF Page Numbering
Add page numbers to any PDF: choose position, number style, starting number and font size, and optionally skip the cover page.
Read the guide · Open the toolPDF to Images
Convert each page of a PDF into a PNG image in your browser.
Read the guide · Open the toolPDF Metadata Viewer
See the hidden details inside a PDF: title, author, producer software, creation and modification dates, page count and PDF version.
Read the guide · Open the toolQR tools
Create QR codes and read them from saved images.
QR Code Generator
Create a QR code for a link or text, choose colours and download it as a PNG.
Read the guide · Open the toolQR Code Scanner
Read a QR code from a saved image or screenshot and see the decoded text or link before you open it.
Read the guide · Open the toolText tools
Count, clean, compare and reformat text.
Word Counter
Count words, characters, sentences and paragraphs as you type, and learn how to hit essay, SEO and social media length targets.
Read the guide · Open the toolCase Converter
Change text between UPPERCASE, lowercase, Title Case, Sentence case and aLtErNaTiNg case in one click, with tips on when each style fits.
Read the guide · Open the toolText Compare
Compare two blocks of text line by line and see what was added or removed.
Read the guide · Open the toolDuplicate Line Remover
Remove repeated lines from a list while keeping the original order.
Read the guide · Open the toolReading Time Calculator
Estimate how long an article takes to read from its word count and reading speed, and learn how to set the speed for your audience.
Read the guide · Open the toolParagraph & Line Counter
Count lines, non-empty lines, paragraphs and characters in any text.
Read the guide · Open the toolDeveloper tools
Format, encode and generate the data developers handle every day.
JSON Formatter & Validator
Format, minify and validate JSON with readable error messages.
Read the guide · Open the toolBase64 Encoder & Decoder
Encode text to Base64 or decode it back, including Unicode text in languages such as Tamil.
Read the guide · Open the toolURL Encoder & Decoder
Percent-encode text for safe use in web addresses and query strings, or decode %20 style text back to readable form.
Read the guide · Open the toolHTML Entity Encoder & Decoder
Convert special characters like < > & and quotes to HTML entities and back, and learn why displaying code on a web page needs encoding.
Read the guide · Open the toolUUID Generator
Generate random version 4 UUIDs in bulk, in lowercase or uppercase, using your browser's secure random source.
Read the guide · Open the toolCalculators
Percentages, ages, units, GST and loan instalments, with the formulas shown.
Percentage Calculator
Work out percentages, percentage of a total and percentage change with clear formulas and examples for discounts, marks, tips and growth.
Read the guide · Open the toolAge Calculator
Calculate exact age in years, months and days between a date of birth and any date, plus total days lived and days until the next birthday.
Read the guide · Open the toolUnit Converter
Convert length, weight, temperature, volume, speed and digital storage units, with the conversion factors explained.
Read the guide · Open the toolGST Calculator
Add or remove GST from a price at 0, 5, 12, 18, 28 or a custom rate, with the formulas and a CGST/SGST split explained.
Read the guide · Open the toolEMI Calculator
Estimate monthly loan instalments, total interest and total repayment from amount, interest rate and tenure, with the EMI formula explained.
Read the guide · Open the tool