Comparison
Anvil vs Appion
Appion wraps the platform's UI frameworks in a WebDriver bridge. Anvil skips the bridge — a native Swift driver on iOS, a native Kotlin driver on Android, and one verb surface across both.
Appion's architecture dates from an era when cross-platform meant "use Selenium semantics everywhere." The WebDriver bridge still works — but every verb is an HTTP round-trip, every session is a state machine you have to tear down, and every driver upgrade is a capability-negotiation dance.
Anvil's drivers (KID on iOS, KAD on Android, KVD on visionOS, KMD on macOS, KWD on watchOS) speak a single JSON-RPC wire with the same 82 verbs on every platform. No session server. No capability dict. No WebDriver HTTP tax on every tap.
And crucially: Appion has no AI agent runtime. If you want the agent to drive your app, you write the agent. Anvil ships it — wired into the same driver surface, same spec format, same replays.
| Feature | Anvil | Appion |
|---|---|---|
| Driver architecture | Native Swift / Kotlin, on-device JSON-RPC | WebDriver bridge + session server |
| HTTP round-trip per verb Appion adds ~20ms HTTP latency per call; Anvil is in-process. | No | Yes |
| AI agent runtime | Yes | No |
| Rejection regression suite | Yes | No |
| Adversarial matrix | Yes | No |
| visionOS / macOS / watchOS drivers | Yes | No |
| Unified verb surface across OSes | 82 verbs, same shape | Per-platform driver quirks |
| Real-device fleet orchestration | BYOD + rental, single dashboard | Grid server required |
| Perf tracing | Perfetto + signpost built-in | DIY Instruments / systrace |
| Perf gating in CI | Yes | No |
| MCP server for AI IDEs | Yes | No |
| Pricing | Free tier + transparent usage-based | Self-hosted free / managed paid |
Why teams switch to Anvil
- Teams moving from Appion report a 3–5× reduction in spec runtime simply from removing the WebDriver bridge — no protocol tax, no HTTP queues.
- Native accessibility tree snapshots (via XCUITest + UiAutomator directly) are higher fidelity than what the WebDriver bridge exposes — more elements, deeper relationships, a11y-AA gating becomes feasible.
- The agent is not an add-on — it shares the exact driver surface the human specs do, so agent findings are reproducible as specs with one click.
- Anvil covers visionOS, macOS, and watchOS today. Appion does not.
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