WebConverter.app
Convert images, audio, and documents — free and private, right in your browser. No files are ever uploaded.
Why WebConverter?
The file converter that never touches your files
Your Files Stay on Your Device
Nothing is uploaded — ever. Conversion runs locally via WebAssembly. Open your browser’s Network tab and verify: zero outbound file transfers.
Instant, Regardless of Connection
No upload, no download, no server queue. A 50 MB image converts in under a second. Works the same on fibre, mobile data, or airplane mode.
Works Offline
Install WebConverter as a Progressive Web App and convert files without any internet connection. Once loaded, it runs entirely on your device.
Free & Unlimited
No sign-ups, no watermarks, no daily limits, no file-size caps. Convert as many files as you need — there is no server to overload.
Images, Audio & PDF
Convert between 14 image formats, extract audio from video to MP3/OGG/WAV/FLAC, and create PDFs from images — all in one tool.
Near-Zero CO₂
No data-centre electricity, no network transfer energy. The only power used is your device’s CPU — a fraction of what server-based converters consume.
Supported Formats
Images, audio, video, and PDF — converted locally in your browser
Image Conversion
14 input formats → 8 output formats
Input: BMP, DDS, GIF, HDR, ICO, JPEG, KTX, PGM, PIC, PNG, PPM, PSD, TGA, WebP
Audio & Video
Extract audio from video or convert between audio formats
Input: MP4, M4A, WAV, OGG, FLAC, WebM, MP3
PDF Tools
Create PDFs from images with optional OCR
Accepts JPEG, PNG, BMP, GIF, WebP, TGA, and more
How It Works
Three steps — no upload, no server, no waiting
Pick a Converter
Choose your target: images, audio, or PDF. Each converter page handles the specific format.
Drop Your Files
Drag and drop files onto the page, or click to browse. Batch conversion is supported — add as many files as you need.
Download Instantly
Conversion runs on your device via WebAssembly. Results download automatically — no server round-trip, no progress bar to watch.
What Powers WebConverter
Open-source technology, running on your device
WebConverter compiles battle-tested C++ image libraries (Magnum) to WebAssembly so they run at near-native speed inside your browser. Audio encoding uses wasm-media-encoders. PDF generation is handled by pdf-lib, with optional Tesseract.js OCR.
Four parallel Web Workers keep the UI responsive during batch conversions. Because every byte of processing happens on your CPU, there is no server to hack, no queue to wait in, and no file-size limit imposed by infrastructure.
The result: convert images to PNG, JPEG, WebP, or EXR; extract audio to MP3 or FLAC; or build PDFs from images — all without uploading a single file.
About WebConverter
Free, private, open-source file conversion
WebConverter.app is a free, open-source file converter. It supports 14 image input formats, 8 image output formats, 4 audio output formats, and PDF creation with OCR. There are no conversion limits, no sign-ups, and no watermarks.
Every conversion runs locally in your browser. No files are ever sent over the network. You can verify this yourself — open DevTools, check the Network tab, and convert a file. You will see zero outbound data. Read more about why this matters and how browser-based conversion works.