How it works

Files stay local when the tool says they do.

NullKit tools load their code from this website, then read and transform a selected file inside the current browser tab. The resulting copy downloads to your device without a file-upload request.

What “local” means

The file contents are handled by browser APIs, JavaScript workers, Canvas, Web Crypto, or WebAssembly on this device. Tool pages disable analytics, and sensitive routes are designed to avoid unnecessary network connections.

Browser compatibility and performance

These tools are designed for current versions of Chrome, Edge, Firefox, and Safari on desktop and mobile.

No particular browser is required for ordinary jobs. Available memory, device speed, file complexity, extensions, and other open tabs can affect demanding work.

For a large PDF, local OCR, or local AI image processing, start with an updated desktop browser and close memory-heavy tabs. If a job runs out of memory or stops repeatedly, trying current Chrome or Edge on a computer is a practical troubleshooting step; it is not a requirement, and the selected file still stays on your device.

What it does not mean

Your browser, operating system, downloaded files, clipboard, extensions, screen recording, malware, and local storage remain outside NullKit’s control. Each tool explains additional format-specific limitations.

Why results are new files

NullKit does not overwrite the original. You receive a new result that can be reviewed before you replace, share, or delete anything.

Lossless and rendered PDF compression

Lossless PDF compression rewrites eligible streams and object structures without deliberately downsampling image pixels. It preserves document content, but an already optimized PDF may not become smaller.

Target-size compression tries lossless optimization first. When that is not enough and you explicitly approve the tradeoff, the tool renders each page as a compressed image and rebuilds the PDF. That can remove selectable text, links, forms, annotations, attachments, metadata, accessibility tags, and digital signatures. The requested size is a target, not a guarantee.

Temporary browser memory

Selected bytes, page renders, intermediate compression attempts, and generated outputs exist temporarily in the current tab's memory. Resetting the tool, closing the tab, or navigating away releases the application's references; browser and operating-system memory management remains outside NullKit's control.