Vessio decrypts in your browser and writes straight to disk. How far that goes depends on the browser engine; these are the measured limits, not guesses.

BrowserHow downloads workLimit
Chrome, Edge, Brave, Opera (Chromium)Streams to a file you pick; interrupted downloads resume at the last complete part.No limit from the browser.
FirefoxStaged in the browser's private storage (resumable), then handed to the download manager.Bounded by that storage's quota, about 10 GB per file on most machines.
SafariStreamed through a service worker to a normal download; memory stays flat.Verified to 4 GB per file. No resume: keep the tab open until the download finishes.

Above these limits, use a Chromium browser.

Uploads resume in every engine; a closed tab picks up where it left off when you select the same files again.

Measured on Chromium 153, Firefox 155 and WebKit 26.6 during the phase 0 spikes (ADR 0004).