Unibase Pay
Enabling autonomous AI agents to seamlessly search, purchase, and pay on the blockchain
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Use the Unibase Pay API to verify and settle x402 payments. Base URL for V2 (recommended):
https://api.x402.unibase.com/v2
Serves BNB Smart Chain, Base, Polygon and Arbitrum One, plus the BSC and Base Sepolia testnets — one endpoint for all of them; the network comes from the payment payload. Call GET /supported for the authoritative list, or see x402.org for protocol details.
Unibase Pay
BNB Chain+ Base+ Polygon & ArbitrumBorn as an x402 facilitator on BNB Chain, Unibase Pay unlocks the ability for AI agents to autonomously search, purchase, and pay — leaning on the chain's low cost and high throughput to bridge intelligent automation and real-world commerce. The same facilitator now settles on Base, Polygon and Arbitrum One, so an agent can pay wherever its counterparty already is.
Full x402 V2 Compatibility
Developers and agents can immediately leverage advanced features like payment monitoring and micropayments on a robust infrastructure.
Privy Custodial Wallet for Agents
Unibase Pay provides agents with a Privy-based third-party custodial wallet, enhancing agent autonomy. Use it directly via MCP and skill.
High-Frequency Micropayments
Enable real-time, low-cost transactions for AI agents and machine-to-machine commerce.
Secure Payment Verification
Cryptographically signed payloads ensure tamper-proof payment processing.
Multi-Network Support
One facilitator across BNB Chain, Base, Polygon and Arbitrum One — plus BSC and Base testnets.
Agent-Ready Infrastructure
Purpose-built for autonomous AI agents to search, purchase, and pay independently.
About x402
The x402 payment protocol is an HTTP-based payment protocol that enables developers running resource servers to accept payments from users using a variety of payment methods. Servers declare payment requirements for specific routes. Clients send cryptographically signed payment payloads. Facilitators verify and settle payments on-chain.
Introduces support for high-frequency micropayments, real-time payment monitoring, and advanced gating capabilities. This evolution transforms x402 from a payment protocol into a comprehensive infrastructure for autonomous agent commerce.
Supported Payment Schemes & Assets
exactSince V1Charge a fixed, known amount.
The classic x402 flow: the server declares a price, the client signs a payload for exactly that amount, and the facilitator verifies and settles it.
uptoNew in V2Authorize a ceiling, settle the actual usage.
The client approves a maximum spend up front and the facilitator settles only what was really consumed. Built for metered billing — per-token LLM calls, per-second compute — where the final price is unknown when the request starts.
batch-settlementNew in V2Aggregate many micropayments into one on-chain transaction.
Payments accumulate off-chain and settle together in a single transaction, so gas is paid once instead of per call. This is what makes sub-cent, high-frequency agent-to-agent payments economical.
All three schemes are available on every supported network — check GET /supported for the live matrix.
Supported assets
EIP-3009 Tokens: Designed for gasless transfers. Users sign a payload, allowing payments without requiring prior approvals on chains.
All ERC20 Tokens via Permit2: With our integrated Permit2 proxy, users can execute payments with any standard ERC20 token simply by signing an off-chain message — opening x402 up to the entire DeFi ecosystem.
Per-network proxy and facilitator contract addresses are listed in the Unibase docs.
V2 Capabilities
Advanced features for the machine economy
API Reference
V2 is the only served version — V1 is listed for migration reference
| Category | API V1Deprecated | API V2 |
|---|---|---|
| Base URL | https://api.x402.unibase.com/v1No longer served — migrate to V2. | https://api.x402.unibase.com/v2 |
| Supported Networks | BSC mainnetBSC testnet | BNB Smart ChainBSC TestnetBaseBase SepoliaPolygonArbitrum One |
| Payment Schemes | exact | exactuptobatch-settlement |
| Supported Assets | XUSD | ERC20 Assets via Permit2EIP-3009 Assets |
| Capabilities | Verify PaymentsSettle Payments | Verify PaymentsSettle PaymentsMonitor PaymentsPayment GatingMicropaymentsMetered Billing (upto)Batch Settlement |
| Methods | — | POST /verify POST /settle GET /supported |