Convert files privately.

No uploads. No accounts. No ads.
useformat runs entirely on your device — your files never leave your browser. Images, audio, video, PDFs, spreadsheets, EPUBs, markdown, archives, and more.

✓ Runs locally ✓ No uploads ✓ No ads ✓ No account
Mode
Fully private — files never leave your device. private
↓
Drop files here
or click to browse · images, audio, video, PDF, spreadsheets, archives, ebooks · how it works
0 files queued
∞
File limit
0
Cost
0
Sign-ups
100%
Private (browser mode)
How it works

Two modes. One file.

Most converters force you to pick: privacy or speed. We give you both. Pick whichever fits the file in front of you.

Browser

Conversion runs locally on your machine using WebAssembly. Files never leave your device.

  • +100% private — nothing uploaded, nothing logged
  • +Works offline — once the page loads, no internet needed
  • +Free forever — no server costs to pass on to you
  • +Fast for small files — under 100MB is instant
  • −Slow on huge files (uses your CPU)
  • −Browser tab can crash on files over ~2GB
  • −Some formats need server-side tools (PDF→DOCX, niche video codecs)
Use when Files are smaller than ~500MB · You care about privacy · It's a common format conversion

Server

For large or unsupported files. Converted with native tools on a small server I run, then automatically deleted after 10 minutes.

  • +Handles huge files — streaming means file size isn't capped by your RAM
  • +Faster on big jobs — server has dedicated CPU for the conversion
  • +Wider format support — FFmpeg, ImageMagick, Pandoc, LibreOffice all installed
  • +Works on weak devices — phone, old laptop, anything that opens a browser
  • −Files briefly leave your device (deleted after 10 min)
  • −Rate-limited per IP to keep the VPS happy
  • −In beta — newly live, may be a little rough
Use when Files are bigger than ~500MB · You're on a phone or old laptop · You need niche formats
Supported formats

What works today.

Everything marked Live runs right now, fully in your browser. Server formats need the bigger tools and are coming with server mode.

Image Live
JPG PNG WebP AVIF GIF BMP HEIC TIFF SVG ICO PSD RAW

Standard formats via Canvas. HEIC via libheif, TIFF via UTIF. RAW/PSD need server.

Audio Live
MP3 WAV FLAC OGG M4A AAC WMA OPUS AIFF AC3

FFmpeg.wasm in browser, native FFmpeg on server.

Video Live
MP4 WebM MOV GIF AVI MKV FLV WMV

Browser-side FFmpeg. Slower on big files (server mode coming for huge videos).

Ebook Live
EPUB→TXT EPUB→HTML MOBI AZW3

EPUB reading via epub.js. MOBI/AZW3 need server (coming).

Text / Markup Live
MD HTML TXT

Markdown to HTML, HTML to Markdown, all browser-side.

PDF Tools Live
PDF→PNG PDF→JPG Split Compress Extract Text

Browser-side via pdf-lib + pdf.js. Office formats need server (soon).

Document Server
DOCX DOC ODT RTF TXT HTML MD EPUB MOBI

Converts on the server (LibreOffice) — file deleted right after.

Spreadsheet Live
XLSX XLS CSV TSV ODS JSON HTML

Browser-side via SheetJS. Fast for most spreadsheets.

Archive Live
ZIP TAR GZ 7Z RAR BZ2

Extract ZIPs in your browser. More archive formats soon.

Presentation Later
PPTX PPT ODP PDF KEY

Server-side only — needs LibreOffice. Slow but reliable.

Ebook Later
EPUB MOBI AZW3 FB2 PDF TXT

Calibre on the server handles all of these.

First-time setup
Loading audio engine

A one-time download (~30MB) that runs all audio conversion locally in your browser. Cached after this, so future visits are instant.

Connecting…
Private: Once loaded, your audio files never leave your device — the engine runs entirely in your browser.