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

The definitive guide to x402, the HTTP-native payment protocol enabling AI agents to pay for APIs per call. Includes ecosystem proof, technical implementation, and Token Metrics integration details.
Token Metrics Team
10 min read
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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.

  1. Step by step: Client makes an API request with the header x-coinbase-402: true.
  2. The server can return 402 with payment details such as amount, recipient, and chain.
  3. The client wallet signs and submits the payment transaction.
  4. 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

  1. Set up a wallet: Create a Base wallet with USDC or TMAI balance.
  2. Install x402 client: npm install x402-axios or pip install x402-httpx.
  3. Choose an endpoint: Browse x402scan or Composer for available APIs.
  4. Write minimal code: Add x-coinbase-402: true header to requests.
  5. Watch payments flow: Monitor transactions in your wallet and on x402scan feed.
  6. Optimize costs: Compare endpoint pricing, use TMAI for 10% discount, cache results when appropriate.

Token Metrics x402 Resources

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.

Frequently Asked Questions

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About Token Metrics
Token Metrics: AI-powered crypto research and ratings platform. We help investors make smarter decisions with unbiased Token Metrics Ratings, on-chain analytics, and editor-curated “Top 10” guides. Our platform distills thousands of data points into clear scores, trends, and alerts you can act on.
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Token Metrics Team
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Recent Posts

Research

Crypto Trading Signals API: Put Bullish/Bearish Calls Right in Your App

Token Metrics Team
4

Timing makes or breaks every trade. The crypto trading signals API from Token Metrics lets you surface bullish and bearish calls directly in your product—no spreadsheet wrangling, no chart gymnastics. In this guide, you’ll hit the /v2/trading-signals endpoint, display actionable signals on a token (e.g., SOL, BTC, ETH), and ship a conversion-ready feature for bots, dashboards, or Discord. Start by creating a key on Get API Key, then Run Hello-TM and Clone a Template to go live fast.

What You’ll Build in 2 Minutes

  • A minimal script that fetches Trading Signals via /v2/trading-signals for one symbol (e.g., SOL).
  • A copy-paste curl to smoke-test your key.
  • A UI pattern to render signal, confidence/score, and timestamp in your dashboard or bot.

Endpoints to add next

  • /v2/hourly-trading-signals (intraday updates)
  • /v2/resistance-support (risk placement)
  • /v2/tm-grade (one-score view)
  • /v2/quantmetrics (risk/return context)

Why This Matters

Action over analysis paralysis. Traders don’t need more lines on a chart—they need an opinionated call they can automate. The trading signals API compresses technical momentum and regime reads into Bullish/Bearish events you can rank, alert on, and route into strategies.

Built for dev speed and reliability. A clean schema, predictable performance, and straightforward auth make it easy to wire signals into bots, dashboards, and community tools. Pair with short-TTL caching or webhooks to minimize polling and keep latency low.

Where to Find

You can find the cURL request for Crypto Trading Signals in the top right corner of the API Reference. Use it to access the latest signals!

Live Demo & Templates

  • Trading Bot Starter: Use Bullish/Bearish calls to trigger paper trades; add take-profit/stop rules with Support/Resistance.
  • Dashboard Signal Panel: Show the latest call, confidence, and last-updated time; add a history table for context.
  • Discord/Telegram Alerts: Post signal changes to a channel with a link back to your app.

How It Works (Under the Hood)

Trading Signals distill model evidence (e.g., momentum regimes and pattern detections) into Bullish or Bearish calls with metadata such as confidence/score and timestamp. You request /v2/trading-signals?symbol=<ASSET> and render the most recent event, or a small history, in your UI.

For intraday workflows, use /v2/hourly-trading-signals to update positions or alerts more frequently. Dashboards typically use short-TTL caching or batched fetches; headless bots lean on webhooks, queues, or short polling with backoff to avoid spiky API usage.

Production Checklist

  • Rate limits: Know your tier caps; add client-side throttling and queues.
  • Retries/backoff: Exponential backoff with jitter; treat 429/5xx as transient.
  • Idempotency: Guard downstream actions (don’t double-trade on retries).
  • Caching: Memory/Redis/KV with short TTLs for reads; pre-warm popular symbols.
  • Webhooks & jobs: Prefer webhooks or scheduled workers for signal change alerts.
  • Pagination/Bulk: Batch symbols; parallelize with care; respect limits.
  • Error catalog: Map common 4xx/5xx to clear fixes; log request IDs.
  • Observability: Track p95/p99 latency, error rate, and alert delivery success.
  • Security: Keep keys in a secrets manager; rotate regularly.

Use Cases & Patterns

  • Bot Builder (Headless): Route Bullish into candidate entries; confirm with /v2/resistance-support for risk and TM Grade for quality.
  • Dashboard Builder (Product): Add a “Signals” module per token; color-code state and show history for credibility.
  • Screener Maker (Lightweight Tools): Filter lists by Bullish state; sort by confidence/score; add alert toggles.
  • Community/Discord: Post signal changes with links to token pages; throttle to avoid noise.
  • Allocator/PM Tools: Track signal hit rates by sector/timeframe to inform position sizing (paper-trade first).

Next Steps

  1. Get API Key — create a key and start free.
  2. Run Hello-TM — confirm your first successful call.
  3. Clone a Template — deploy a bot, dashboard, or alerting tool today.

FAQs

1) What does the Trading Signals API return?

A JSON payload with the latest Bullish/Bearish call for a symbol, typically including a confidence/score and generated_at timestamp. You can render the latest call or a recent history for context.

2) Is it real-time? What about latency/SLOs?

Signals are designed for timely, programmatic use with predictable latency. For faster cycles, use /v2/hourly-trading-signals. Add caching and queues/webhooks to reduce round-trips.

3) Can I use the signals in a live trading bot?

Yes—many developers do. A common pattern is: Signals → candidate entry, Support/Resistance → stop/targets, Quantmetrics → risk sizing. Always backtest and paper-trade before going live.

4) How accurate are the signals?

Backtests are illustrative, not guarantees. Treat signals as one input in a broader framework with risk controls. Evaluate hit rates and drawdowns on your universe/timeframe.

5) Do you provide SDKs and examples?

You can integrate via REST using JavaScript and Python snippets above. The docs include quickstarts, Postman collections, and templates—start with Run Hello-TM.

6) Polling vs webhooks for alerts?

Dashboards often use cached polling. For bots/alerts, prefer webhooks or scheduled jobs and keep retries idempotent to avoid duplicate trades or messages.

7) Pricing, limits, and enterprise SLAs?

Begin free and scale as you grow. See API plans for allowances; enterprise SLAs and support are available.

Research

Fundamental Grade Crypto API: Real Crypto Fundamentals in One Score

Token Metrics Team
3

Most traders chase price action; Fundamental Grade Crypto API helps you see the business behind the token—community traction, tokenomics design, exchange presence, VC signals, and DeFi health—consolidated into one score you can query in code. In a few minutes, you’ll fetch Fundamental Grade, render it in your product, and ship a due-diligence UX that drives trust. Start by grabbing your key at the Get API Key page, Run Hello-TM to verify your first call, then Clone a Template to go live fast.

What You’ll Build in 2 Minutes

A minimal script to fetch Fundamental Grade from /v2/fundamental-grade for any symbol (e.g., BTC).

  • Optional curl to smoke-test your key in seconds.
  • A drop-in pattern to display the grade + key drivers in dashboards, screeners, and research tools.

Endpoints to consider next

  • /v2/tm-grade (technical/sentiment/momentum)
  • /v2/price-prediction (scenario planning)
  • /v2/resistance-support (risk levels)
  • /v2/quantmetrics (risk/return stats)

Why This Matters

Beyond price, toward quality. Markets are noisy—hype rises and fades. Fundamental Grade consolidates hard-to-track signals (community growth, token distribution, liquidity venues, investor quality, DeFi integrations) into a clear, comparable score. You get a fast “is this worth time and capital?” answer for screening, allocation, and monitoring.

Build trust into your product. Whether you run an investor terminal, exchange research tab, or a portfolio tool, Token Metrics discovery helps users justify positions. Pair it with TM Grade or Quantmetrics for a balanced picture: what to buy (fundamentals) and when to act (signals/levels).

Where to Find

The Fundamental Grade is easily accessible in the top right of the API Reference. Grab the cURL request for seamless access!

Ready to build?

  • Get API Key — generate a key and start free.
  • Run Hello-TM — verify your first successful call.
  • Clone a Template — deploy a screener or token page today.

Watch the demo: VIDEO_URL_HERE. Compare plans: Scale confidently with API plans.

FAQs

1) What does the Fundamental Grade API return?

A JSON payload with the overall score/grade plus component scores (e.g., community, tokenomics, exchange presence, VC backing, DeFi health) and timestamps. Use the overall grade for ranking and component scores for explanations.

2) How fast is the endpoint? Do you publish SLOs?

The API is engineered for predictable latency. For high-traffic dashboards, add short-TTL caching and batch requests; for alerts, use jobs/webhooks to minimize round-trips.

3) Can I combine Fundamental Grade with TM Grade or signals?

Yes. A common pattern is Fundamental Grade for quality filter + TM Grade for technical/sentiment context + Trading Signals for timing and Support/Resistance for risk placement.

4) How “accurate” is the grade?

It’s an opinionated synthesis of multiple inputs—not financial advice. Historical studies can inform usage, but past performance doesn’t guarantee future results. Always layer risk management and testing.

5) Do you offer SDKs and examples?

You can use REST directly (see JS/Python above). The docs include quickstarts, Postman, and ready-to-clone templates—start with Run Hello-TM.

6) Polling vs webhooks for fundamentals updates?

For UI pages, cached polling works well. For event-style notifications (upgrades/downgrades), prefer webhooks or scheduled jobs to avoid spiky traffic.

7) What about pricing, limits, and enterprise SLAs?

Begin free and scale as you grow. See API plans for allowances; enterprise SLAs and support are available—contact us.

Research

Fundamental Grade Crypto API: Invest with Conviction Using Real Project Signals

Token Metrics Team
4

Most traders chase price action; Fundamental Grade Crypto API helps you see the business behind the token—community traction, tokenomics design, exchange presence, VC signals, and DeFi health—consolidated into one score you can query in code. In a few minutes, you’ll fetch Fundamental Grade, render it in your product, and ship a due-diligence UX that drives trust. Start by grabbing your key at the Get API Key page, Run Hello-TM to verify your first call, then Clone a Template to go live fast.

What You’ll Build in 2 Minutes

A minimal script to fetch Fundamental Grade from /v2/fundamental-grade for any symbol (e.g., BTC).

  • Optional curl to smoke-test your key in seconds.
  • A drop-in pattern to display the grade + key drivers in dashboards, screeners, and research tools.

Endpoints to consider next:

  • /v2/tm-grade (technical/sentiment/momentum)
  • /v2/price-prediction (scenario planning)
  • /v2/resistance-support (risk levels)
  • /v2/quantmetrics (risk/return stats)

Why This Matters

Beyond price, toward quality. Markets are noisy—hype rises and fades. Fundamental Grade consolidates hard-to-track signals (community growth, token distribution, liquidity venues, investor quality, DeFi integrations) into a clear, comparable score. You get a fast “is this worth time and capital?” answer for screening, allocation, and monitoring.

Build trust into your product. Whether you run an investor terminal, exchange research tab, or a portfolio tool, Fundamental Grade lets users justify positions. Pair it with TM Grade or Quantmetrics for a balanced picture: what to buy (fundamentals) and when to act (signals/levels).

Where to Find The Fundamental Grade

The Fundamental Grade is easily accessible in the top right of the API Reference. Grab the cURL request for seamless access!

Build Smarter Crypto Apps & AI Agents with Token Metrics

Token Metrics provides real-time prices, trading signals, and on-chain insights all from one powerful API. Grab a Free API Key

How It Works (Under the Hood)

Fundamental Grade aggregates multiple project-quality signals into a normalized score and label (e.g., Strong / Average / Weak). Typical sub-signals include:

  • Community: momentum across channels (dev activity/user traction signals where applicable).
  • Tokenomics: supply schedule, distribution, unlock dynamics, incentives.
  • Exchange Presence: venue coverage, depth/liquidity proxies.
  • VC/Investor Signals: quality/durability of backing and ecosystem support.
  • DeFi Health: integrations, TVL context, composability footprint.

At query time, you call /v2/fundamental-grade with a symbol; responses include the overall score plus component scores you can visualize. For dashboards with many assets, batch fetches and short-TTL caching keep pages responsive. If you push alerts (e.g., “Fundamental Grade upgraded”), prefer webhooks or queued jobs to avoid hammering the API.

Production Checklist

  • Rate limits: Know plan caps; add client throttling and request queues.
  • Retries/backoff: Exponential backoff + jitter; surface actionable error messages.
  • Idempotency: Prevent duplicate downstream actions on retried calls.
  • Caching: Use memory/Redis/KV with short TTLs; pre-warm popular symbols.
  • Webhooks & jobs: For alerts, use signed webhooks or scheduled jobs; log delivery outcomes.
  • Pagination/Bulk: When covering many tokens, paginate or process in batches.
  • Error catalog: Map 4xx/5xx to user-visible fixes; log request IDs.
  • Observability: Track p95/p99 and error rate per endpoint; alert on spikes.
  • Security: Keep API keys in secrets managers; rotate regularly.

Use Cases & Patterns

  • Screener Maker: Rank tokens by Fundamental Grade, filter by market cap/sector, and add “rising fundamentals” badges for discovery.
  • Dashboard Builder: On each token page, show the headline grade with a component chart; link to methodology for transparency.
  • Research & PM Tools: Flag downgrades/upgrades to prompt re-evaluation; attach notes to component changes (e.g., DeFi health drop).
  • Allocator / Risk: Require a minimum Fundamental Grade before inclusion; rebalance only when grade crosses thresholds.
  • Community/Discord: Post weekly upgrades as digest messages with links back to your app.

Next Steps

  • Get API Key — generate a key and start free.
  • Run Hello-TM — verify your first successful call.
  • Clone a Template — deploy a screener or token page today.
  • Watch the demo: VIDEO_URL_HERE
  • Compare plans: Scale confidently with API plans.

FAQs

1) What does the Fundamental Grade API return?

A JSON payload with the overall score/grade plus component scores (e.g., community, tokenomics, exchange presence, VC backing, DeFi health) and timestamps. Use the overall grade for ranking and component scores for explanations.

2) How fast is the endpoint? Do you publish SLOs?

The API is engineered for predictable latency. For high-traffic dashboards, add short-TTL caching and batch requests; for alerts, use jobs/webhooks to minimize round-trips.

3) Can I combine Fundamental Grade with TM Grade or signals?

Yes. A common pattern is Fundamental Grade for quality filter + TM Grade for technical/sentiment context + Trading Signals for timing and Support/Resistance for risk placement.

4) How “accurate” is the grade?

It’s an opinionated synthesis of multiple inputs—not financial advice. Historical studies can inform usage, but past performance doesn’t guarantee future results. Always layer risk management and testing.

5) Do you offer SDKs and examples?

You can use REST directly (see JS/Python above). The docs include quickstarts, Postman, and ready-to-clone templates—start with Run Hello-TM.

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