Astral vs Dia:
An Open-Protocol Agentic Browser Alternative
Dia is The Browser Company's answer to the AI browser moment — and it is an interesting one. Taking the heritage of Arc and layering an AI-native experience on top of a browser engine is a reasonable approach. We respect the ambition.
Astral starts from a different premise: an open protocol called UADP that gives AI agents structured access to your data — without rendering HTML, without a browser engine, and without your private keys ever touching a server. Local-first, passkey-signed, and built for the agentic web.
Astral vs Dia: open protocol meets AI browser
What makes Astral different
Three architectural decisions set Astral apart from any AI-browser approach.
Open UADP protocol
UADP is not a product — it is a specification. Services publish a /.well-known/uadp.json manifest, agents discover it automatically, and the data comes back as structured JSON schema types. No HTML parsing, no fragile scraping. Any developer can implement UADP.
Read the spec →Passkey-signed tokens
Every UADP request Astral makes is signed by a passkey backed by your device's secure hardware (Secure Enclave on Apple Silicon, TPM on Windows). The service verifies the signature without ever seeing your private key. Zero passwords. Zero phishing vectors.
ComponentConfig-driven UI
Your UI is serializable JSON — not hardcoded layouts. Tell your agent 'show my email in compact mode on the left, banking cards on the right' and ComponentConfig updates instantly. It persists to your local profile and syncs across devices via encrypted payload.
Frequently asked questions
How is Astral different from Dia?
Both Dia and Astral put AI at the centre of the browser experience. The key difference is protocol and privacy. Astral is built on UADP — an open, structured-data protocol where your agent accesses services via signed JSON instead of scraping HTML. Your private keys never leave your device (Secure Enclave / TPM). Dia wraps an AI layer around a conventional browser engine with a proprietary approach.
Is Astral open source?
No. Astral is a free download, but its source code is not public. What is open is the protocol: the UADP specification is published on GitHub under the MIT license, so any service can implement it and any agent can consume it. We believe open protocols are essential for an agentic web.
What does local-first mean for Astral?
Local-first means your private keys, your agent configuration, and your data cache all live on your device. Astral uses WebAuthn passkeys backed by Secure Enclave (macOS/iOS), TPM (Windows), or StrongBox (Android). No cloud service ever sees your private key. Sync across devices uses encrypted payloads signed by your passkey.
Can Astral access services that don't support UADP?
Yes. Astral includes a scraping adapter layer — YAML-defined adapters that normalise HTML responses into UADP schema types. So even services without a UADP manifest can be accessed through the same structured agent interface. UADP-native services just get richer, more reliable data.
Try the open-protocol agentic alternative
Experience what local-first, open-protocol, agent-native browsing feels like. Free download, no account needed.
Download Astral