x402 & HTTP 402 Explained: Why Wallet-Paid API Calls Are Winning (and Where Token Metrics Fits)

What Is x402?
x402 is an open-source, HTTP-native payment protocol developed by Coinbase that enables pay-per-call API access using crypto wallets. It leverages the HTTP 402 Payment Required status code to create seamless, keyless API payments.
It eliminates traditional API keys and subscriptions, allowing agents and applications to pay for exactly what they use in real time. It works across Base and Solana with USDC and selected native tokens such as TMAI.
Start using Token Metrics X402 integration here. https://www.x402scan.com/server/244415a1-d172-4867-ac30-6af563fd4d25
TLDR — The x402 Value Proposition
x402 transforms API access by making payments native to HTTP requests.
Feature | Traditional APIs | x402 APIs |
Authentication | API keys, tokens | Wallet signature |
Payment Model | Subscription, prepaid | Pay-per-call |
Onboarding | Sign up, KYC, billing | Connect wallet |
Rate Limits | Fixed tiers | Economic (pay more = more access) |
Commitment | Monthly/annual | Zero, per-call only |
How to use it: Add x-coinbase-402: true header to any supported endpoint. Sign payment with your wallet. The API responds immediately after confirming micro-payment.
Token Metrics integration: All public endpoints available via x402 with per-call pricing from $0.017 to $0.068 USDC (10% discount with TMAI token).
Explore live agents: https://www.x402scan.com/composer.
How HTTP 402 Payment Required Works — Technical Deep Dive
The Protocol Flow
The HTTP 402 status code was reserved in HTTP/1.1 in 1997 for future digital payment use cases and was never standardized for any specific payment scheme. x402 activates this path by using 402 responses to coordinate crypto payments during API requests.
- Step by step: Client makes an API request with the header x-coinbase-402: true.
- The server can return 402 with payment details such as amount, recipient, and chain.
- The client wallet signs and submits the payment transaction.
- The server verifies the payment on-chain, then processes the original request and returns 200 with data.
Why this matters: It eliminates intermediary payment processors, enables true machine-to-machine commerce, and reduces friction for AI agents.
Ecosystem Proof: x402 Is Winning — Three Validation Points
CoinGecko Recognition
CoinGecko launched a dedicated x402 Ecosystem category in October 2025, tracking 700+ projects with over $1 billion market cap and approximately $213 million in daily trading volume. Top performers include PING and Alnalyst, along with established projects like EigenCloud.
Base Network Adoption
Base has emerged as the primary chain for x402 adoption, with 450,000+ weekly transactions by late October 2025, up from near-zero in May. This growth demonstrates real agent and developer usage.
x402scan Composer — Where Agents Pay in Real Time
Composer is x402scan's sandbox for discovering and using AI agents that pay per tool call. Users can open any agent, chat with it, and watch tool calls and payments stream in real time.
Top agents include AInalyst, Canza, SOSA, and NewEra. The Composer feed shows live activity across all agents.
Explore Composer: https://x402scan.com/composer
Token Metrics x402 Integration — Concrete Implementation
What We Ship
Token Metrics offers all public API endpoints via x402 with no API key required. Pay per call with USDC or TMAI for a 10 percent discount. Access includes trading signals, price predictions, fundamental grades, technology scores, indices data, and the AI chatbot.
Check out Token Metrics Integration on X402. https://www.x402scan.com/server/244415a1-d172-4867-ac30-6af563fd4d25
Data as of October, 2025.
Pricing Tiers
Important note: TMAI Spend Limit: TMAI has 18 decimals. Set max payment to avoid overspending. Example: 200 TMAI = 200 * (10 ** 18) in base units.
Full integration guide: https://api.tokenmetrics.com
Why x402 Changes Everything for AI Agents
- Eliminates onboarding friction. Agents can discover and use new APIs instantly without human intervention for API key management or billing setup.
- Enables true agentic commerce. Agents pay for exactly what they use, which makes micro-transactions economically viable. This unlocks composition of multiple specialized services.
- Aligns incentives. API providers get paid per call, users only pay for value received, and agents can optimize costs by choosing best-fit providers. Network effects accelerate as more endpoints adopt x402.
Use Cases Already Working
- Crypto analytics agents: Pull Token Metrics data on demand to answer market questions, generate trade signals, or build custom dashboards.
- Research automation: Chain together x402 endpoints like Twitter search, Tavily extract, Firecrawl, and Token Metrics to gather and structure data.
- Portfolio management: Agents monitor positions, fetch real-time prices, calculate risk metrics, and execute rebalancing decisions using paid data sources.
- Trading strategy backtests: Access historical OHLCV, grades, and signals data via x402 without committing to monthly subscriptions.
- Multi-chain intelligence: Combine Base and Solana x402 services for cross-chain analysis and arbitrage discovery.
Ecosystem Participants and Tools
Active x402 Endpoints
Key endpoints beyond Token Metrics include Heurist Mesh for crypto intelligence, Tavily extract for structured web content, Firecrawl search for SERP and scraping, Twitter or X search for social discovery, and various DeFi and market data providers.
Infrastructure and Tools
- x402scan: Explorer and analytics platform tracking all x402 activity across chains.
- Composer: Hosted sandbox for discovering and using x402-enabled agents.
- x402-axios and x402-httpx: Client libraries for Node.js and Python.
- Coinbase Agent Kit: SDK integration for building x402-native agents.
- LangChain connectors: Framework integration for agent workflows.
Common Questions About x402
How is x402 different from traditional API keys?
x402 uses wallet signatures instead of API keys. Payment happens per call rather than via subscription. No sign-up, no monthly billing, no rate limit tiers. You pay for exactly what you use.
Which chains support x402?
Currently Base and Solana. Most activity is on Base with USDC as the primary payment token. Some endpoints accept native tokens like TMAI for discounts.
Do I need to trust the API provider with my funds?
No. Payments are on-chain and verifiable. You approve each transaction amount. No escrow or prepayment is required.
What happens if a payment fails?
The API returns 402 Payment Required again with updated payment details. Your client retries automatically. You do not receive data until payment confirms.
Can I use x402 with existing API clients?
Yes, with x402 client libraries such as x402-axios for Node and x402-httpx for Python. These wrap standard HTTP clients and handle the payment flow automatically.
Getting Started Checklist
- Set up a wallet: Create a Base wallet with USDC or TMAI balance.
- Install x402 client: npm install x402-axios or pip install x402-httpx.
- Choose an endpoint: Browse x402scan or Composer for available APIs.
- Write minimal code: Add x-coinbase-402: true header to requests.
- Watch payments flow: Monitor transactions in your wallet and on x402scan feed.
- Optimize costs: Compare endpoint pricing, use TMAI for 10% discount, cache results when appropriate.
Token Metrics x402 Resources
- API documentation: https://api.tokenmetrics.com
- x402 integration guide: https://api.tokenmetrics.com
- Pricing calculator: https://api.tokenmetrics.com
- Code examples: https://api.tokenmetrics.com
- Composer agents: https://x402scan.com/composer
- Live endpoint status: https://x402scan.com
What's Next for x402
Ecosystem expansion. More API providers adopting x402, additional chains beyond Base and Solana, standardization of payment headers and response formats.
Agent sophistication. As x402 matures, expect agents that automatically discover and compose multiple paid endpoints, optimize costs across providers, and negotiate better rates for bulk usage.
Disclosure
Educational content only, not financial advice. API usage and crypto payments carry risks. Verify all transactions before signing. Do your own research.
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