Introduction

Vellar is a programmable payment platform for Stellar — the payment layer for the agent economy. It combines a live x402 facilitator with Bazaar discovery, on-chain spending and provenance policies, and a passkey smart wallet, so that people and AI agents can discover, pay for, and be governed on services on Stellar — with the rules enforced by consensus, not by your code.

The vellar-sdk on npm is the client half; the x402 stack Vellar runs is the other half. It's live on Stellar testnet today.

One install, one object:

const vellar = createVellarWallet({ network, appName, kit, sac, backend, isValidAddress });
await vellar.create({ username });        // passkey → smart account
await vellar.pay({ to, amount, token });  // simulate → passkey → sponsored submit

The four pillars

• x402 payments — a live verify/settle facilitator that re-simulates each payment on-chain, settles the SEP-41 transfer, and sponsors the fee. People and agents pay for HTTP-402 resources; buyers hold no XLM.
• Bazaar discovery — every settled payment auto-catalogs its resource, so an agent can find what to pay for by keyword search over HTTP or an MCP server. This is the piece a bare facilitator doesn't have.
• On-chain governance — spending-limit and verified-only policies co-sign inside the wallet's __check_auth, so an over-budget or unverified payment is rejected by consensus and no funds move. Provenance the chain enforces, not a claim in a doc.
• Passkey smart wallet — WebAuthn onboarding (Face ID / Touch ID), Soroban smart-contract accounts, fee-sponsored submission, no key custody, no silent signing. The account layer the rest is built on.

For the agent economy

Vellar isn't only a human wallet — it's built for autonomous agents that spend money. Three surfaces make that safe:

• Agent keys — mint a scoped session key an agent holds itself. Give your agent a budget, not your keys.
• Policies — a spending-limit policy caps how much; a verified-only policy restricts the agent to contracts with reproducible, verified source (provenance, not an audit). Both are enforced on-chain in the wallet's __check_auth, so they bind even a fully compromised agent.
• x402 Facilitator — Vellar runs a hosted x402 verify/settle facilitator with Bazaar discovery, so agents can find and pay for services (and it accepts the policy-governed payments other facilitators reject).

The x402 stack

The SDK is the client half. The other half is the x402 payment layer Vellar runs and the SDK talks to — the piece that actually moves money between people, agents, and the services they pay. It's live on Stellar testnet today.

• Facilitator (verify & settle) — when a payment arrives, the facilitator re-simulates it against the chain first (running the buyer's Soroban auth entry to confirm it would succeed), then settles the SEP-41 transfer and sponsors the fee from its own account. Buyers hold no XLM; a seller points at the facilitator once and charges per request without touching Soroban RPC, auth entries, or fee handling.
• Bazaar discovery — every settled payment auto-catalogs its resource, so services show up just by getting paid, with no separate registration. An agent searches the catalog by keyword over HTTP or through an MCP server, and each result carries the exact asset, amount, and payTo it needs to pay. This is how an agent finds what to pay for in the first place.
• Policy-governed payments — because the wallet and policy layers are Vellar's too, a payment can be governed on-chain: the spending-limit and verified-only policies co-sign inside __check_auth, so an over-budget or unverified payment is rejected by consensus and no funds move. The facilitator raises its fee ceiling to accept these, where the reference facilitator rejects them.

Together that's the full loop: an agent discovers a service in Bazaar, pays through the facilitator under a budget the chain enforces, and can only pay code whose source is verified — none of which your application code has to police. See x402 and the Facilitator guide.

Who this is for

Developers building on Stellar who want login + a wallet without becoming wallet-infrastructure experts, teams who want programmable, on-chain security (spending limits, co-signers) instead of client-side checks that can be bypassed, and anyone building AI agents that need to transact under limits they can trust.

Status

Early and evolving. Testnet-ready; mainnet is gated on remaining security-review and deployment work. APIs may change before 1.0.

New here? Go to Installation, then the Quickstart to get a working wallet in a few minutes.