VirusTotal Sidekick by hejeble

VirusTotal Sidekick lets you check any download link against VirusTotal straight from the right click menu, while keeping your links and files private by default.

How it works

• Right click a link and choose "Check file with VirusTotal".
• A confirmation page opens and shows you what is about to happen. Nothing is fetched until you click.
• The extension downloads the file, computes its SHA-256 hash, and looks that hash up on VirusTotal. If the file is already known, its report opens.
• If the file is not known, you can choose to upload it for analysis. Nothing is uploaded without your consent.

Private by default

• Only the file's hash is sent for the lookup. Your original link is never sent to VirusTotal for a normal check.
• File downloads are made without your cookies, so authenticated content is not pulled into the check.
• Your API key is stored locally on your device, is never synced, and is entered in a hidden password field.
• Access to websites is optional and requested per site, only when you check a link from that site.
• Requests to private or reserved network addresses are blocked.

Large files

• VirusTotal's public API accepts uploads up to 32 MB. For files larger than that, the extension can fall back to submitting the link instead, so you still get a result.
• This fallback is guarded. Links that look like they carry a token or credential are refused outright. For other links, the query string, fragment, and any embedded credentials are stripped before submission, and you are shown the exact link and asked to confirm. You can opt out of the per link prompt, and turn it back on, from the options page.

Other touches

• Recent lookup results are cached locally for 24 hours to save your API quota.
• The options, confirmation, and upload pages follow your light or dark browser theme.

Getting started

You will need a VirusTotal API key. A free key is available by signing up for a VirusTotal Community account. Paste it into the extension options once and you are ready to go.