A scanner looks for known bad things and misses the rest. Kernel opens each file inside an isolated sandbox with no network entitlement, extracts only the content — the vector page, the pixels, the frames — and writes a brand-new file around it. Whatever wasn't content is gone by construction, not by blocklist.
Not "metadata" in the abstract — specific fields, sitting in the container, that most viewers never show you.
Each file is opened in its own isolated sanitizer service — no network entitlement, no filesystem access beyond the one file handle it was given.
Converting a transparent PNG to HEIC would flatten the transparency — so Kernel keeps the original format and tells you why. Same logic for HDR range, chroma resolution and a stereo pair. Most tools quietly do the lossy thing. An app willing to say what it won't do is making a claim about everything else it does.
Convert a transparent PNG logo to HEIC for a smaller batch output.
HEIC has no alpha channel worth trusting for this case — the conversion would paint the transparent area white. Kernel keeps the file as a rebuilt PNG instead, and says so right on the row. It never enlarges a file to force a format either — the same refusal instinct in reverse.
Drop a batch onto Kernel and it lays them out as a contact sheet — you watch it clear itself, one tile at a time. Every finished copy carries a SHA-256 you can check yourself; drag a tile straight into another app the moment it's done.
While Kernel is open, a watched folder cleans new arrivals automatically — a Downloads folder, a folder of mail attachments. Pause any folder any time. Watching runs only while the app is open; it isn't a background launchd agent.
Seal a rebuilt file into an archive signed by this Mac's Secure Enclave. Drop that archive back into Kernel any time afterward and it tells you whether the content still matches its seal — entirely offline, and without trusting anything inside the file itself.
Hand Kernel a file on iPhone and get a clean copy back — same rebuild logic, no navigation to learn.
Tap once to see the specifics, struck through. Tap once more to clean the batch. The share sheet, Photos, Files, drag and drop, Shortcuts, Siri, the Action button and Control Center — Kernel meets files wherever they already are.
Honestly scoped: on iPhone the rebuild runs inside the app itself — iOS has no separate sandboxed service the way macOS does. Heavy video re-encoding and cryptographically sealed archives stay Kernel-for-Mac's job, and the app says so rather than pretending otherwise.
Dangerzone shares Kernel's core insight — rebuild, don't scan — and is free, open-source and well-regarded. The honest contrast isn't "better", it's what each one is built for.
| Kernel | Dangerzone | Metadata strippers | |
|---|---|---|---|
| Method | Rebuild | Rebuild | Strip fields |
| Runtime | Native, no container | Podman/Docker container | Native |
| Formats | PDF, images, video, spatial video | PDF, Office docs, images | Mostly images |
| Batch | Hundreds, visibly, SHA-256 per file | No batch view | Varies |
| Offline seal + verify | Yes | No | No |
| Price | 9,99 € once | Free, open-source | ≈4 € |
Dangerzone details as of publishing — check freedomofpress/dangerzone for the current feature set.
Kernel's sanitizer services hold no network entitlement at all — not disabled by preference, absent from the binary. iCloud-evicted files are skipped rather than downloaded. Built by a solo developer in France.
Kernel rebuilds them clean, on your Mac or iPhone, before they ever leave.