# Arc by Atlas Associates Inc.

> Arc is a privacy-first, end-to-end encrypted messenger built on libsignal v0.94.1 (the same cryptographic library used by Signal and WhatsApp), extended with NIST FIPS-203 post-quantum protection via PQXDH (X25519 + ML-KEM-1024). Atlas Associates does not access plaintext message content, does not sell user data, and does not run targeted advertising.

## Technology

- Client: Flutter (iOS, Android, macOS). End-to-end encryption runs natively via libsignal; the E2EE messenger is a native app, not a web client.
- Cryptography: libsignal v0.94.1 (Rust) via flutter_rust_bridge FFI — Signal Protocol (PQXDH ML-KEM-1024, Double Ratchet, Sender Keys) + XEdDSA signatures.
- Backend: Elixir/Phoenix PreKey service on Google Cloud Run (europe-west1), Firebase (Firestore message delivery, Auth, Storage, App Check, FCM).

## Core principles

- End-to-end encryption (E2EE) by default for all messages, voice, video, files, reactions, and call signaling.
- Post-quantum cryptography (PQXDH with ML-KEM-1024) protects against "harvest now, decrypt later" attacks.
- Ephemeral by default: each message has a sender-configured expiry; server-side purge runs on a plan-tiered sweep (Essential daily at midnight JST, Premium every 6 hours JST, Intelligence every 5 minutes). Mutual Burn (Vanish-on-Read) is available on the Premium and Intelligence plans for 1:1 chats — when both parties tap the mail icon to confirm read, the plaintext is purged from devices and the encrypted server copy follows the plan-tiered sweep.
- No phone number authentication — accounts identified by Arc IDs (e.g. arc_XXXX).
- No advertising. No data sales. No backdoors. Zero government requests received to date.

## Pricing (effective June 2026)

- Essential: free. Full E2EE messaging. Premium features unlock by watching ads.
- Premium: USD 8 / month (JPY 800 / month). Ad-free.
- Intelligence: USD 25 / month. Ad-free, additional AI features.
- Group chats: 1,000 members maximum on every plan.
- General availability: mid-June 2026. Beta participants had full access during the preceding beta period.

## Pages

- [Home](https://www.atlasassociates.io/en/): Atlas Associates overview.
- [Arc Messenger](https://www.atlasassociates.io/en/arc/): Product overview.
- [Security](https://www.atlasassociates.io/en/arc/security/): Cryptographic design.
- [Pricing](https://www.atlasassociates.io/en/arc/pricing/): Plan comparison and feature matrix.
- [Competitive Comparison](https://www.atlasassociates.io/en/arc/competitive-comparison/): 9-axis security scoring vs. 19 other messengers (Signal, WhatsApp, Threema, iMessage, Telegram, etc.).
- [Website Privacy Policy](https://www.atlasassociates.io/privacypolicy/): How Atlas Associates handles information collected through atlasassociates.io.
- [Arc Privacy Policy](https://www.atlasassociates.io/arc/privacy-policy/): How the Arc messenger handles user data.
- [Maison Apéro Privacy Policy](https://www.atlasassociates.io/winelovers/privacy-policy/): How the Maison Apéro app handles user data.
- [Technology](https://www.atlasassociates.io/en/arc/technology/): Stack overview (Flutter, Rust libsignal, Elixir Phoenix, Firebase, GCP).
- [Architecture](https://www.atlasassociates.io/en/arc/architecture/): Protocol and system architecture overview.
- [AI Characters](https://www.atlasassociates.io/en/arc/ai-characters/): On-device and cloud AI characters (Étoile, Méthode, 卑弥呼, SEAN, Muse, APEX, Rosetta), all within E2EE.
- [Key Sync](https://www.atlasassociates.io/en/arc/key-sync/): Multi-device key synchronization and encrypted backup.
- [Tips & FAQs](https://www.atlasassociates.io/en/arc/tips-faqs/): User-facing how-to.
- [Tracker](https://www.atlasassociates.io/en/arc/tracker/): Tracker feature for wine and beverage logging.
- [Winery Mode](https://www.atlasassociates.io/en/arc/winery/): Winery work management.

## Contact

- support@atlasassociates.io
- https://www.atlasassociates.io