Give your agent a budget, not your keys.

Vellar is building the agent-payments stack for Stellar on x402, smart accounts that pay HTTP-402 APIs autonomously, budgets enforced on-chain, and trust-ranked discovery. Secured by passkeys, not seed phrases.

Launch web app →Build with the SDK
Agent key◇
AGENT
research-botUSDC
session key GDW3…K7QPexpires in 7d
BUDGET USED
3.20/ 25 USDC
12 paymentsenforced on-chain
Spend limitVerified onlyRevoke
Autonomous payment⚡
GET /v1/research402
policy check✓ under budget
PAYMENT-SIGNATURE✓ signed
settled on-chain200 OK
Bazaar◎
✓ Trust-ranked
Weather API0.05 USDC · verified
Pay
Translate API0.02 USDC · verified
Pay
GPU Inference0.25 USDC · 1.2k settlements
Pay
Building on x402

The agent-payments stack for Stellar.

x402 is the open protocol that turns HTTP 402 into machine-payable APIs. We're building every layer of it on Stellar: the payer, smart accounts with scoped agent keys, the settlement rails, and trust-ranked discovery so agents pay the right services.

01

Agent keys with on-chain budgets

One passkey tap mints your agent a scoped session key, locked to the tokens you choose, capped by a spending-limit policy. The budget lives in a contract, not in code the agent could bypass, and you can revoke the key remotely any time.

02

Autonomous payments via the SDK

The first x402 client built for Stellar smart accounts. One call handles the 402 challenge, sign headlessly, pay, get the resource. An over-budget payment fails on-chain before any money moves.

03

Facilitator + trust-ranked Bazaar

Our open-source facilitator verifies and settles x402 payments, including policy-governed smart accounts other facilitators reject, and its Bazaar lets agents discover payable APIs ranked by real settlement data and contract verification.

Read the agent-keys guideFacilitator on GitHub
One request, end to end

Your agent hits a paywall. It pays it.

One call handles the whole challenge: parse the 402, check the on-chain budget, sign headlessly, retry, settle on Stellar. Over budget? The chain refuses before any money moves.

research-bot · autonomous402 → 200
GET /v1/research402
price0.10 USDC
policy check✓ under budget
PAYMENT-SIGNATURE✓ signed
settled on-chain200 OK
Playground

Don't take our word for it, go break it.

The playground runs the whole Vellar stack live on Stellar testnet. Your first payment funds a real wallet for you, then every settlement, every budget check, and every refusal happens on-chain, and you can inspect all of it.

Learn the flow

Make a real API payment and inspect every hop, the 402 challenge, the signed header, the settled 200.

Break it

Corrupt a payment five different ways, or try to poison the Bazaar catalog, and watch the facilitator refuse every one.

The Bazaar, live

Browse every resource the facilitator has observed, each one with a working pay button.

Quest mode

Five levels that walk the whole protocol, from your first payment to bonds and settlement.

Break it, live⌁
Tamper signatureReuse nonceOverspend
GET /v1/research402
X-PAYMENT headertampered
facilitator verify✗ refused
funds moved0.00
✓ Nothing charged, that's the point
Open the playground →
Everyday actions

Your everyday Stellar wallet.

Web-first

Create and use your smart wallet straight from the browser, no download, no seed phrase. Just a passkey.

You are sending166.6 XLM
FeeSponsored
Policy✓ OK
Signed withPasskey
Launch web app

Developer SDK

Add passkey login and a Stellar smart wallet to your app in minutes, self-custodial, fee-sponsored, no seed phrases.

$ npm install vellar-sdk
import { createVellarWallet }
await vellar.create()✓ passkey
await vellar.pay()✓ sent
await vellar.x402.fetch(url)✓ paid
Read the docs
Browser extension

Connect to any Stellar dApp.

The Vellar extension pairs with your wallet once, then approves dApp connections and signing, with the same passkey and on-chain policies you already set. No seed phrase ever enters the browser.

01

Pair once

Approve the extension from your wallet with a single passkey tap. It gets a secure device key, bound to your account, and it expires automatically.

02

Connect to dApps

When a Stellar app requests access, the extension shows exactly which site is asking. You approve per-origin, nothing connects silently.

03

Review & sign

Every transaction is decoded and shown before you approve. Your spending limits and policies are enforced on-chain, so the extension can't bypass them.

VS Code extension

Charge for an API without leaving your editor.

Vellar x402 scans the open file for a route, asks how much to charge in USDC, and writes the 402 challenge, verification and settlement boilerplate straight into your handler. Nothing else in the file changes.

Works with Express, Fastify and the Next.js App Router. Pick a route from the command palette, set a price, and review real, typed code, ready to install and ship.

ExpressFastifyNext.js
Get the extensionRead the docs
Vellar x402 listed on the VS Code Marketplace
Questions

Frequently asked questions

Still curious? Reach us at hello@vellar.xyz or read the developer docs.

Can my AI agent spend from my wallet? +
Yes, that's what agent keys are for. Mint your agent a scoped session key with an on-chain spending limit and it can pay x402-enabled APIs autonomously, no passkey prompt needed. The budget is enforced by a policy contract inside your wallet, not by the agent's code. Go over it and the chain refuses to settle. Revoke the key at any time.
Is Vellar custodial? +
No. Vellar is fully self-custodial, your account and keys live on Stellar and in your device's secure enclave. We never hold your funds or your passkeys.
What happens if I lose my device? +
Register multiple passkeys across devices, and use account policies to add recovery co-signers. Losing one device doesn't lock you out, which is the whole point of moving past single seed phrases.
Do I need the browser extension? +
Not to get started, Vellar is web-first. The extension is there when you want one-click connections to Stellar dApps with the same passkey and policies you've already set.
What are programmable policies, exactly? +
On-chain rules enforced by the network: spending limits, required co-signers, time locks and allow-lists. They apply to every transaction automatically, so a compromised session still can't drain the account.
Is it ready for teams and developers? +
Yes. Teams get multi-signer policies and shared controls; developers get an SDK, contract-verification tooling and the extension's connect API.

Ship agent payments today.

Add passkey login, a Stellar smart wallet and x402 agent payments to your app in minutes, self-custodial, fee-sponsored, no seed phrases.

Read the docsView on GitHub