Images → WebP
Default quality80%
Output format
AVIF is ~20–30% smaller than WebP at the same quality. Falls back to WebP automatically if a browser can't decode it.
PNG & JPEG are encoded to WebP. 100% is visually lossless; lower values trade quality for size. SVGs are minified with SVGO and kept as
.svg. Re-convert any row with the ↻ button after changing settings.Drop PNG, JPEG, or SVG files
Or click to select · batch uploads supported
Fonts → WOFF
Converts TTF and OTF files to WOFF with zlib compression — smaller than TTF and supported in every browser. Filenames are preserved.
Drop TTF or OTF files
Or click to select · batch uploads supported
Video → WebM
Default target size (applies to new files)5 MB
Container
Codec
Video transcoding runs fully in your browser via
ffmpeg.wasm (multithreaded build when your browser supports SharedArrayBuffer). The core loads on first use (~30 MB) and is cached after that. Files under ~250 MB are reliable; larger files can exceed the browser's ~2 GB WASM memory ceiling — for those, use a desktop tool.Container choice: WebM (VP8/VP9) is best for the web — smaller files and open codecs. MP4 (H.264 / H.265) is universal across players and devices but can't carry alpha.
Alpha transparency is auto-detected and preserved when you pick WebM (e.g. ProRes 4444 MOV → yuva420p WebM). MP4 codecs flatten alpha. For HEVC with alpha (Apple's hvc1+alpha extension, distinct from regular HEVC), use Shutter Encoder — browser-side encoders can't produce it.
Drop video files
MP4, MOV, MKV, WebM · works best under ~250 MB · larger files may exceed browser memory