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Framimo

Methodology

Last updated 14 October 2026

This page explains how Framimo converts files without uploading them, and how we decide what a converter page may claim.

How a conversion runs in your browser

Pipeline: your file is decoded in the browser, edited, encoded in a worker and saved as a download. The only network path is the opt-in server encode for animated AVIF.Your filevideo, images, GIFDecode + editvideo el., canvasEncodeworker: WASM / WebCodecsDownloadBlob on your deviceOpt-in server encodeanimated AVIF only
Every step except the dashed box happens inside your browser tab. The dashed path is offered only for animated AVIF in browsers without an AV1 encoder, and only after you confirm it; the browser first encodes an H.264 intermediate locally, the server encodes it with libaom-av1, and the file is deleted once the result is ready.

Encoders we use

OutputEncoderWhere it runsTransparency
GIFgifenc (JavaScript) with optional Floyd–Steinberg ditheringWeb Worker on your deviceNo (flattened onto white)
Animated WebPlibwebp compiled to WebAssembly (lossy VP8 + alpha)Web Worker on your deviceYes
MP4Browser WebCodecs H.264 encoder, muxed with mediabunnyOn your deviceNo (flattened onto white)
Animated AVIFBrowser WebCodecs AV1 encoder + Framimo's AVIF-sequence muxerOn your device; opt-in server (libaom-av1) only where no AV1 encoder existsNo (flattened onto white)
Still AVIFBrowser WebCodecs AV1 encoder, single frame, 8-bit 4:2:0On your device onlyNo (flattened onto a colour you pick)

Animated tools capture video from its first 8 seconds and keep up to 60 frames, scaled to at most 480 px wide. Uploads into the page are limited to 100 MB in total.

Which browsers encode what

Support is detected at run time, not guessed from the browser name: the page asks WebCodecs whether it can configure an AV1 or H.264 encoder. This table reflects typical results for current versions.

OutputChrome, EdgeFirefoxSafari
GIF, animated WebPLocalLocalLocal
MP4LocalLocal if WebCodecs H.264 encoding is availableLocal if WebCodecs H.264 encoding is available
Animated AVIFLocalOpt-in serverOpt-in server
Still AVIFLocalNot availableNot available

Format facts come from primary sources

Statements about what a format is or can do are checked against specifications and reference documentation, such as the AV1 Image File Format specification and the MDN image format guide. Each page lists its sources at the bottom.

Browser support comes from live compatibility data

We point to Can I use instead of copying version numbers, which go stale. Whether encoding works in your browser is detected at run time by asking the browser if it can encode AV1.

We do not publish invented savings figures

How much smaller an AVIF is than a JPG, PNG or WebP depends on the image and the quality setting. Rather than quote a headline percentage, the converters show your original size next to the result for every file, so the number you see is measured on your own image.

Limits are stated plainly

If a tool cannot do something, the page says so. Examples: GIF, MP4 and AVIF output here does not carry an alpha channel, so transparent areas are flattened onto a solid colour; exports carry no audio; and the conversion is lossy, so keep your originals.

Benchmarks

When we publish size comparisons between formats, they will come from named, publicly licensed test clips run through these exact encoders, with the browser version, settings, output sizes and encode times listed so anyone can reproduce them. Until then, tool pages describe differences qualitatively and the editor shows the measured size of your own export.

Reviews and corrections

Pages show a last-reviewed date. If you find something inaccurate, tell us at support@framimo.com and we will correct it. See also About.