Quasar

Quasar is the backend of TUWA (Stage 3, “Backend & Sync”). Pulsar tracks a transaction in the browser while the tab is open; Quasar tracks the same transaction on a server until it reaches a final status, keeps the history of your app for every device, and notifies your backend with signed webhooks. Your server talks to it with @tuwaio/quasar-sdk.

🔄 How Quasar Fits In


Browser (Pulsar store)                Your server                     Quasar API
──────────────────────                ───────────                     ──────────
executeTxAction
  │ beforeTxProcess ──────────────────────────────────────────────▶  GET /v1/engine/monitoring/health
  │ wallet signs, Pulsar starts tracking
  │ onRemoteCreate(tx) ─────────────▶ Server Action / route
                                        │ checks the SIWX session
                                        │ quasar.pulsar.syncCreate ──▶ POST /v1/engine/pulsar/sync
                                                                          │ tracks the transaction
                                                                          │ (EVM, Safe, ERC-4337, Solana)
Nova Transactions history ◀──────── quasar.pulsar.getHistory ◀─────  GET /v1/engine/pulsar/history
                                    Your webhook endpoint ◀────────── POST, signed with HMAC-SHA256

Your server holds the key. The browser never calls Quasar with the secret key: it calls your server, which checks that the user owns the wallet (with a SIWX session) and then calls Quasar. The Quasar transaction sync guide builds this flow.
Tracking runs twice. A fast phase follows the transaction until it is confirmed, and a later phase checks it again for reorganizations and lagging RPC nodes. Quasar tracks the transactions of the Pulsar trackers: EVM transactions, Safe multisig transactions, ERC-4337 user operations and Solana signatures.
Webhooks notify your backend when a transaction succeeds, fails or is replaced. See Webhooks.

☁️ Quasar Cloud and Quasar Community

Quasar comes in two editions with the same tracking engine and the same API, so @tuwaio/quasar-sdk works with both: only its baseUrl changes.

	Quasar Cloud	Quasar Community Edition
Hosting	Managed by TUWA: API at `https://api.tuwa.io`, dashboard at quasar.tuwa.io	Your servers, with Docker Compose (TuwaIO/quasar-community , Apache-2.0)
Tenants	Organizations with members, several apps each	Single-tenant: one administrator
Sign-in to the panel	Accounts with SIWX wallet sign-in and passkeys	Email, password and TOTP two-factor authentication in the Payload admin (`/admin`)
Quotas	Metered per organization (Quotas & Limits)	Set so high that they do not limit a single node
Emails, billing	Onboarding and low-quota emails, on-chain billing	None

The Community Edition has no SIWX sign-in, no passkeys, no transactional email, no billing and no customer portal. There is no export of the history from Quasar Cloud to a self-hosted node yet: moving an app means pointing baseUrl of @tuwaio/quasar-sdk at your node, and the history starts there. See Self-Hosting.

📚 Next Steps

Create an app and get its keys: Apps & Keys.
Sync the transactions of your React app: Quasar transaction sync guide, or the complete app in the Full-Stack React guide.
Receive webhooks, also on localhost: Webhooks.
Browse the endpoints in the API Reference, and the client in the @tuwaio/quasar-sdk reference.