How do I convert a file online for free?

Drop your file onto FileFettle, select your output format, and click Convert. Your file is processed instantly inside your browser — no upload, no registration, completely free.

Do my files get uploaded to a server?

Never. FileFettle uses WebAssembly and the Canvas API to process files entirely in your browser. Zero bytes of your data are ever sent to any server.

What file formats can I convert?

Over 80 formats across 5 categories — images (JPG, PNG, WebP, AVIF, HEIC, GIF, SVG, TIFF, BMP), audio (MP3, WAV, FLAC, OGG, AAC, M4A, OPUS, AIFF, WMA), video (MP4, WebM, MOV, AVI, MKV, WMV, MPEG), documents (PDF, DOCX, TXT, HTML, Markdown), and data (CSV, JSON, XML, YAML, XLSX, XLS, ODS, TOML, INI).

Is there a file size limit?

No. Since conversion runs in your browser, there's no server-side size limit. The only constraint is your device's available RAM — which handles most files without issue.

Is FileFettle free to use?

Yes — completely free, forever. No subscriptions, no paywalls, no ads, no tracking. Optional voluntary contributions help keep the project running.

Why does my first video or audio conversion take a moment to start?

Video and audio conversion uses FFmpeg compiled to WebAssembly. The first time you convert, your browser downloads a ~30 MB package — this only happens once and is then cached, so subsequent conversions start instantly.

How do I convert an image to JPG, PNG, or WebP?

Drop your image (supports JPG, PNG, HEIC, GIF, TIFF, BMP, SVG, AVIF and more), choose your output format — JPG, PNG, WebP, etc. — optionally resize or adjust quality, then click Convert.

File Encrypt

Encrypt any file with AES-256-GCM using a password. Decrypt .ffenc files back to their originals. Files never leave your device.

File to encrypt

📄

Drop any file here

or click to browse

Password

⚠️ There is no password recovery. If you forget your password, the file cannot be decrypted. Store it safely.

🔒AES-256-GCM encryption runs entirely in your browser using WebCrypto. Files never leave your device.

How the encryption works

AES-256-GCM

Military-grade authenticated encryption. Protects both the file content and detects any tampering.

PBKDF2

Your password is stretched with 250,000 iterations of SHA-256 to resist brute-force attacks.

Random salt + IV

A unique 16-byte salt and 12-byte IV are generated for every encryption, so identical files produce different output.