Most image compression tools upload your photos to a server. That’s fine for casual images, but not okay when users are working with personal documents like Aadhaar cards, PAN cards, or government exam forms.
I ran into this issue myself while helping someone upload a photo with a strict 20KB file size limit. Most tools either broke the quality or failed to hit the exact size. So I decided to build my own tool that works 100% inside the browser — no backend, no APIs, no uploads.
That’s how ResizeKB.tech was born.
PROBLEM I WANTED TO SOLVE
Government and job application portals in India often require:
- Exact file size limits (20KB, 50KB, 100KB)
- Specific dimensions
- Clean background images
- No quality loss
Most tools:
- Upload images to a server
- Compress blindly
- Don’t allow exact KB targeting
- Create privacy issues
My goal was:
- Exact size control
- No server
- No upload
- Works instantly
TECH STACK
- HTML5
- Vanilla JavaScript
- HTML Canvas API
- Browser File API
HOW IT WORKS
- User selects an image
- Image loads using FileReader
- It is drawn onto a hidden canvas
- Quality + resolution are adjusted
- Export happens using canvas.toBlob()
- Loop runs until exact KB size is reached
Everything happens locally. No file is uploaded anywhere.
BIGGEST CHALLENGES
- Maintaining quality under 20KB
- Handling large phone images
- Browser memory crashes
- Different compression results in different browsers
PRIVACY
- No login
- No uploads
- No server
- No tracking
LIVE TOOL
You can check the browser Network tab — there is zero upload.
FINAL NOTE
This started as a personal fix for government form uploads and slowly became a daily-use tool for thousands of users.
If you're building browser-based tools or care about privacy-first apps, happy to connect.
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