47 free tools, all running in your browser

File tools that never upload your files

Kilnfile is a free set of 47 file tools for PDFs, images, video, audio and text that run entirely inside your browser. Nothing is sent to a server, there is no signup, no file size limit and no watermark. Drop a file in, and the work happens on your own device.

Processed on your device, nothing uploadedWorks offline once a tool has loaded.

Most used tools

All 47 tools

PDFMerge PDFCombine several PDF files into one document, in the order you choose, entirely in your browser.PDFCompress PDFMake a PDF smaller for email or upload, with a choice of lossless or image-based compression.PDFPDF to JPGTurn each page of a PDF, or only the pages you pick, into JPG images at your chosen resolution.PDFJPG to PDFCombine JPG, PNG and WebP images into a single PDF with one page per image.ImageCompress JPGReduce JPG file size in your browser with a quality slider and optional max width.ImageHEIC to JPGTurn iPhone HEIC and HEIF photos into JPG files that open anywhere.MediaMP4 to MP3Pull the soundtrack out of any MP4 and save it as an MP3 at the bitrate you choose.MediaCompress VideoCut a video's file size by more than half without it leaving your device.TextWord CounterCount words, characters, sentences and paragraphs as you type, with reading and speaking time.TextJSON FormatterValidate JSON, pretty print it with your chosen indentation, sort keys or minify it.ImageResize ImageChange image dimensions by width, height, percentage or exact size without uploading anything.PDFPDF to WordExtract the text of a PDF into an editable Word document, right in your browser.

PDF tools

14 tools

Merge, split, compress, convert, protect and edit PDF files in your browser. Free, no signup, no file limits, and your PDFs never leave your device.

Image tools

12 tools

Compress, resize, crop and convert JPG, PNG, WebP, HEIC and SVG images in your browser. Free, no signup, no limits, and photos never leave your device.

Video and audio tools

10 tools

Convert MP4 to MP3, MOV to MP4, trim and compress video, make GIFs and convert audio formats. Runs in your browser with FFmpeg, no upload, no signup.

Text and developer tools

11 tools

Word counter, case converter, JSON formatter, CSV to JSON, base64 and URL encoding, diff checker, markdown to HTML and more. Instant, free and private.

Why does Kilnfile process files on your device?

Most online converters upload your file to a server, queue it, process it, and give you a download link. That means a copy of your bank statement, medical letter or unreleased video sits on someone else’s machine. Kilnfile takes the opposite approach: the conversion code (open-source libraries such as pdf-lib, PDF.js and FFmpeg compiled to WebAssembly) is downloaded to your browser and runs there. The file never leaves your computer or phone.

This also removes the usual restrictions. There is no file size cap beyond what your device can handle, no daily limit, no watermark and no account. The site is funded by display advertising, which is why you will see a few adverts around the tools. They load after the tool is ready so they never slow you down.

Kilnfile compared with typical upload-based converters
Feature	Kilnfile	Typical upload converter
Where the file is processed	Your device	Their server
File size limit	None (device memory)	Often 25 to 100 MB free
Files per day	Unlimited	Often 2 to 5 free
Signup	Never	Often required
Watermarks	None	Common on free tier
Works offline	Yes, once loaded	No

Source: Kilnfile review of the free tiers of the ten most-visited converter sites, 20 September 2026.