Methodology · The whole pipeline
How nothing leaves your browser.
"We don't upload your files" is a claim every converter site makes, including the ones that upload your files. This page doesn't ask you to believe the claim — it shows you the pipeline and gives you three independent ways to catch us if it were false.
These aren't marketing numbers — each one is checkable from your side of the screen, and the sections below show how.
The pipeline, start to finish
When you choose a file on any converter here, your browser's File API opens it in memory — the file is already on your machine, so nothing travels anywhere. Decoding turns the bytes into raw pixels: for JPG, PNG, and WEBP the browser's own decoder does this natively; for HEIC, which most browsers can't read, a WebAssembly build of the open-source libheif library does it inside the tab. The pixels are drawn onto a canvas, re-encoded into the output format, wrapped in a Blob — a chunk of memory in your tab — and linked for download. Six steps, all local. A server never appears in that sequence because this site does not have one: it is static files served from a CDN, with no backend, no database, and no API to receive an upload even if the code tried to send one.
Verify it — three independent ways
The network meter. Every converter's readout strip has a "network since file read" instrument. It uses your browser's own PerformanceObserver to count every request the page makes from the moment your first file is read. It reads 0, in green, and is wired to flip red on the first request — an instrument, not a slogan.
The developer-tools check. Press F12, open the Network tab, then convert a file. After the one-time decoder fetch (which happens before your file is read — see below), the request list stays empty. This check doesn't rely on anything we wrote; it's the browser reporting on us.
The airplane-mode check. The strongest one. Visit any converter once; a service worker caches the page and its code on your device. Now switch off wifi entirely and convert — it works, because nothing about the conversion ever needed a connection. A site that secretly uploaded files could not pass this test, no matter what its copy says. That structural difference is the entire reason this site exists.
The one thing that does download: the decoder
Honesty requires naming the exception. HEIC decoding needs code your browser doesn't ship — a 1.4 MB WebAssembly build of libheif (with the libde265 HEVC decoder), the same open-source library used industry-wide. It downloads once per device — never in response to your file, and always before your file is read, so the network meter's zero is honest. It is served unmodified from this site under the LGPL-3.0 license, with the license text and provenance published alongside it at /vendor/libheif/. It is the only third-party code on the site, and after the first visit it lives in your cache — which is why the tools work offline.
What never exists here
No accounts and no sign-ups. No cookies. No local storage — not even a settings byte; close the tab and every trace of your session is gone, because results live in tab memory and are released when you leave. No copies "deleted after 24 hours," because no copies exist to delete. And one side effect worth knowing: re-encoding through a canvas strips EXIF metadata from every output — GPS coordinates, device model, timestamps. For photos you're about to share, that's a privacy feature; if you need the capture date, note it before you convert.
The honest limits
Client-side conversion spends your device's resources instead of a server's. Decoding happens in RAM at about four bytes per pixel, so a 48-megapixel HEIC needs roughly 200 MB while converting — a low-memory phone should convert large batches a few files at a time. HDR and 10-bit captures are tone-mapped to standard 8-bit color, since that is what JPG and PNG hold. Very old browsers without WebAssembly can't run the HEIC decoder at all — the page will say so rather than quietly failing. These are the trade-offs of the architecture; we consider them a fair price for the property that no file of yours ever exists anywhere but in your hands.