Browser comparison
Zen vs Sill: the two calm-browser philosophies
Zen and Sill are kindred spirits — both built around workspaces, a compact sidebar, and the belief that browsing should be quieter. Zen gets there as an open-source Firefox fork that runs everywhere; Sill gets there as a native WebKit app that runs only on your Mac and sends nothing anywhere. Here's how to pick.
Full disclosure: this studio builds Sill. This is written as the comparison worth reading anyway — Zen's genuine strengths included, its details drawn from its own public documentation.
Of every browser on this site's comparison list, Zen is the closest to Sill in spirit. It's a community-driven, open-source browser built on Firefox's Gecko engine, with workspaces, split view, a compact hideable sidebar, and a lively theming scene ("Mods"). If you're choosing between these two, you've already decided you want calm — the question is which foundation you want it on.
The quick answer
Choose Zen if…
- You need Windows or Linux — Zen runs on all three desktops
- You want Firefox add-ons (uBlock Origin and the rest of the Gecko ecosystem)
- Fully open-source, community-governed software matters to you
- You want Firefox Sync across machines
- You love theming and deep UI customization
Choose Sill if…
- You want a native macOS app — WebKit, Apple-platform conventions, light on the battery
- You want whole-workspace hibernation with scroll position restored, not just tab unloading under memory pressure
- You want glanceable favorites — mail counts and meeting nudges, read locally
- You want zero network calls of the browser’s own, with sensitive sites never observed
- You want an API client and MCP explorer without hunting for add-ons
Zen vs Sill: core features
| Feature | Sill | Zen |
|---|---|---|
| Engine | WebKit (native macOS) | Gecko (Firefox-based) |
| Platforms | macOS 14+ (Apple Silicon & Intel) | macOS, Windows, Linux |
| Price | Free (early access) | Free |
| Account required | No | No |
| Open source | Source on GitHub | Yes |
| Workspaces | Yes — hibernating workspaces | Yes — Workspaces |
| Memory model | Whole workspaces hibernate and release their memory; favorites stay loaded | Gecko unloads tabs under memory pressure; split view for side-by-side |
| Ad & tracker blocking | Built in — ad networks blocked natively; videos never autoplay | Firefox tracking protection; uBlock Origin via add-ons |
| AI features | None — routine detection is deterministic, local, and off by default | None built in |
| Browser's own network calls | Zero of its own — no telemetry, no analytics, no account | Low — some Mozilla services remain (updates, safe browsing) |
| Developer tools | API client, MCP explorer, Web Inspector, JSON tree viewer | Firefox DevTools |
| Sync & mobile | None — single Mac, fully local | Firefox Sync; no mobile app (pairs with Firefox mobile) |
| Extensions | No extension store (blocking & dev tools are built in) | Yes — Firefox add-ons |
Accurate to the best of our knowledge as of 13 July 2026; Zen's details come from its public documentation.
Where Zen shines
- Open source, all the way down. Zen is community-built and auditable, on an engine (Gecko) that is itself the main independent alternative to Chromium and WebKit. For verifiability-by-reading, nothing here beats it.
- Runs on everything, customizes everything. Windows, Linux and macOS, with Mods and theming that let you reshape the UI to taste, plus the full Firefox add-on catalogue.
- Free browser freedom. Firefox Sync gives you cross-device continuity without a proprietary account ecosystem.
See it for yourself: visit Zen’s official site ↗ (opens in a new tab).
Where Sill shines
- Native, not ported. Sill is a WebKit app built for macOS 14+ — the engine Safari uses, with macOS conventions and efficiency rather than a cross-platform shell.
- Hibernation as a feature, not a fallback. Gecko unloads tabs when memory runs low; Sill hibernates deliberately — switch workspaces and the old one releases its memory entirely, waking later exactly where you left it.
- The heads-up layer. Unread mail on the Gmail icon, a card before your next meeting — read locally from your own signed-in pages, off by default, never transmitted. Zen has no equivalent.
- Quieter still. Zen is low-telemetry; Sill is no-telemetry — zero network calls of its own, with banking, health and government sites excluded from even local observation.
The privacy picture
Both browsers take privacy seriously, differently. Zen inherits Firefox's Enhanced Tracking Protection and Mozilla's documented (and trimmable) service connections, and being fully open source, you can read exactly what it does. Sill's approach is subtraction: no account, no telemetry, no cloud services at all, plus a local, deterministic, opt-in routine engine whose records you can inspect and delete on the Learning page. Zen is verifiable by reading; Sill is verifiable by watching your own network monitor.
Verdict
Frequently asked questions
Is Zen based on Firefox?
Yes — Zen is an open-source browser built on Firefox's Gecko engine, which means Firefox add-ons, Firefox Sync and Firefox DevTools all work, and it inherits Mozilla's tracking protection.
Do Zen and Sill both have workspaces?
Yes, and they’re philosophically similar. The differences: Sill hibernates entire workspaces (memory released, scroll position restored on wake) rather than relying on unload-under-pressure, and adds glanceable favorites — mail counts and meeting nudges — that Zen doesn’t attempt.
Can I use uBlock Origin in Sill?
No — Sill has no extension store. Ad-network blocking is built in natively instead, and videos never autoplay. If a specific Firefox add-on is essential to you, Zen is the better fit.
Which is more private, Zen or Sill?
Both are far quieter than mainstream browsers. Zen is fully open source with low, trimmable telemetry inherited from Firefox. Sill makes zero network calls of its own — no telemetry to trim — and its routine detection is local, deterministic, opt-in and excludes sensitive sites entirely.
Try it yourself:Sill is free early access for macOS 14+ — no account, nothing leaves your Mac.
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