Free  ·  No Sign-up  ·  Browser-Based

The tools you need for
everyday digital work

Convert files, resize images, generate QR codes, merge PDFs, shorten links, and calculate anything — all running directly in your browser.

File Converter Image Resizer QR Code PDF Toolkit URL Shortener Age Calculator

Latest Articles

View All
All Tools

What would you like to do today?

Pick a tool and start immediately — no account, no installation, no cost.

URL Shortener

Paste any long URL to get a short link, a QR code, and a real-time click analytics dashboard — all generated in one step.

Short Links QR Code Click Analytics

QR Code Generator & Scanner

Generate a QR code from text, a URL, or an uploaded file. Scan any QR code using your device camera or by uploading an image. Download as PNG.

Generate Analytics Dynamic QR

File Converter

Convert between documents, images, audio, and video formats. Supports 100+ format combinations including PDF to Word, JPG to PNG, and MP4 to MP3.

100+ Formats convert No Install

Image Resizer

Resize photos to exact pixel dimensions or by percentage. Compress JPG, PNG, WebP, and GIF files while keeping the image sharp and clear.

Resize Compress JPG · PNG · WebP

Age Calculator

Enter a birth date to get the exact age in years, months, and days. Handles leap years correctly and supports both past and future date calculations.

Years · Months · Days calculator Instant Result

Interest Calculator

Calculate simple or compound interest on any loan or investment. Adjust rate, tenure, and compounding frequency to compare different financial scenarios.

Simple Interest Compound Visual Charts

PDF Toolkit

Merge multiple PDFs, split by page range, compress file size, and convert PDFs to Word or images. Most operations run directly inside your browser.

Merge Split Compress Convert

Unit Converter

Switch between metric and imperial units across length, weight, temperature, volume, and area.

Length & Weight Temperature instant result

Time Calculator

Find the exact difference between two dates, add or subtract time durations, and convert time units . Accounts for daylight saving changes automatically.

Date Difference Add / Subtract time unit converter
9+
Free Tools
100%
Browser-Based
0
Sign-ups Needed
Free
Always & Forever
Why 21K Tools

Built differently, on purpose

Every decision behind these tools was made to save you time and respect your privacy.

Private by Default

Most tools process data inside your browser using JavaScript. Your files never leave your device.

No Wait, No Queues

Browser-based processing means results appear in seconds — no upload queue, no server lag.

Zero Sign-up Friction

No account, no email, no password. Open any tool, complete your task, and close the tab.

Works on Any Device

Every tool is responsive and tested on desktop, tablet, and mobile. The QR scanner uses your phone camera directly.

How It Works

Three steps, every time

The same simple flow works across all nine tools on this site.

1

Open the tool

Click a tool link. The page loads in seconds with no login screen or pop-ups in your way.

2

Upload or enter your data

Drop a file, paste a URL, or type numbers directly. The interface is intentionally minimal.

3

Download or copy the result

Save the output file, copy the result, or share a link. Nothing is stored after you leave the page.

Real Use Cases

Who uses 21K Tools?

These tools solve specific, everyday problems across different types of users.

Students

  • Convert assignment files from DOCX to PDF before submission
  • Compress images for presentations without losing clarity
  • Calculate an exact age in years and days for science or statistics tasks
  • Find the time difference between two historical dates for a class project

Freelancers & Remote Workers

  • Merge separate client contracts into one PDF for easy review
  • Shorten campaign tracking URLs and attach a QR code for print use
  • Resize a profile photo to a platform's exact pixel requirements
  • Run a quick compound interest calculation when reviewing project payment terms

Small Business Owners

  • Generate QR codes for digital menus, payment pages, or social profiles
  • Compress product images before uploading to an online store or catalogue
  • Convert audio or video files between formats for different publishing platforms
  • Track how many people click a shortened link printed on a flyer or brochure
FAQ

Common questions answered

Things people ask before using these tools for the first time.

Yes. Every tool on 21K Tools is free with no subscription tiers, no trial limits, and no watermarks on output files. The platform is independently funded and maintained by its developer, Nithish.
No account is required for any tool on this site. You open the page, complete your task, and close the tab. No email, no password, and nothing stored about your session.
Most tools process data directly inside your browser using JavaScript, which means the file never leaves your device. For tools that require a server (such as certain video conversions), the file is processed and immediately discarded — it is not saved, indexed, or shared with anyone.
Yes. Every tool is responsive and works on Android and iOS browsers without any app download. The QR code scanner can access your phone's camera directly from the browser.
Email contact@21k.tools or use the contact form in the Help Center. Every message is read by the developer and several tools were added based directly on user suggestions.
File size limits vary by tool and depend on what your browser can handle for client-side processing. For most image and PDF tasks, files up to several hundred megabytes work without issues. Server-side tools may have lower limits which are shown clearly in the tool interface.

Ready to get started?

Pick any tool above and complete your task in under a minute. No account required. No cost.

Browse all tools Read the blog