Free online tools
PDF, images, video, text, calculators and more. Everything is processed right in your browser — no upload, no sign-up.
e.g. merge PDF
- 103
- free tools
- 12
- categories
- 3
- languages
Popular tools
Compress Image
Reduce a JPG or WebP file size with quality control; PNG is only re-encoded.
Image
Word and Character Counter
Count words, characters, lines, and paragraphs in real time, right in your browser.
Text
Merge PDF
Merge several PDFs into one document, in any order.
JWT Decoder
Decode a JWT and see its header, payload, and expiration — without verifying the signature.
Development
Compound Interest Calculator
Calculate compound interest with monthly contributions.
Financial
Color Picker
Pick a color and see HEX, RGB and HSL instantly.
Colors
Length Converter
Convert length between meter, km, mile, foot, and inch.
Converters
Brazilian CPF Validator
Validate a Brazilian CPF instantly.
Validators
Compress Video Online
Shrink a video's file size by choosing resolution and quality.
Video Editing
Percentage Calculator
Calculate percentages: what X% of Y is, increases, discounts, and more.
Calculators
QR Code Generator
Generate QR Codes for text, links, Wi-Fi, Pix, vCard, SMS and more, free.
Generators
Freelance Hourly Rate Calculator
Find what to charge per hour and project to hit your income goal.
Business
Categories
Don't take our word for ittest it yourself
Kastavo has no server processing your files. Turn your internet off and try: most tools keep working.
What's new
4 new tools (Chmod Calculator, .env Formatter, Hex to Text Converter and Watermark PDF), plus the new Blog, the Privacy page and a refreshed look.
Why use Kastavo?
100% free
Every tool is free, with no sign-up. Where there is a file size limit, it is shown on the tool itself.
Fast and straightforward
Fast results, right in your browser, nothing to install.
Always growing
We add new tools regularly, so the catalog keeps growing.
Multiple languages
Content in Portuguese, English and Spanish, with units and formats for your language.
Didn't find the tool you needed?
Tell us which tool you'd like to see on Kastavo.
A solo project by Michel Davi, with new tools added regularly.