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Wil Piña
Wil Piña

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I Built an API Marketplace Where AI Agents Pay Per Request in USDC — Canary Live, MCP Discovery, 100 Endpoints in 8 Days, Solo"

Description: "AETHERIUS is live on Base Mainnet with real USDC payments. 100 endpoints. MCP discovery for AI agents. Canary settling $0.001 USDC via Coinbase CDP. Built solo in 8 days."
Series: "Building the Agent Economy"

TL;DR: AETHERIUS is an open-source API marketplace where AI agents pay per request in USDC on Base Mainnet. No accounts. No API keys. No subscriptions. 100 live endpoints. Canary LIVE. MCP discovery deployed. Python + JavaScript SDKs. All verifiable on-chain. Built solo in 8 days with $5.80 in ETH.

🚀 Try it now:

curl https://34-156-149-38.sslip.io/aetherapi/v1/x402/base-stats
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What Changed Since Last Time

Six days ago I wrote about building 80 endpoints in 4 days. Here's what happened since:

What Sep 6 (Last Article) Sep 10 (Now)
Endpoints 80 (60 paid + 20 free) 100 (60 paid + 40 free)
Payment mode Simulated Canary LIVE (real $0.001 USDC via CDP)
MCP Not deployed 10 tools over HTTPS SSE
Discovery Manual Bazaar manifest (/mcp/discovery)
Governance None SECURITY + CODEOWNERS + TERMS + CITATION
Wiki Empty 9 institutional pages
Build time 4 days 8 days
Total commits 150+ 215+

The big one: The canary route (/v1/data/uuid) is settling real USDC on Base Mainnet via Coinbase CDP facilitator. Not simulated. Not testnet. Real money, real settlement, real data.


Why This Matters (30-second version)

Every API on the internet requires a human to sign up. But in 2026, AI agents are the primary consumers of APIs. They don't have email addresses. They can't fill out forms. They can't manage subscriptions.

But they can send crypto.

AETHERIUS solves this: An agent hits an API, gets a 402 Payment Required response with a USDC amount, pays on-chain, and receives data. Total time: ~200ms. No humans involved.

This is not a demo. This is live on Base Mainnet with real USDC payments flowing right now.


The Numbers

Metric Value
Total endpoints 100
Paid endpoints 60 ($0.001–$0.03/call)
FREE endpoints 40 (20 x402 Intelligence + 20 QuantumXBrain)
Payment currency USDC on Base Mainnet
Canary status LIVE — /v1/data/uuid settling real $0.001 USDC
MCP tools 10 over HTTPS SSE
Build time 8 days
Total capital $5.80 ETH
Team size 1 (me)
Tests 39 passing
SDKs Python v2.0 + JavaScript
Grant applications Base Batches 004 ($100K) + Creator Grant ($4K)

How It Works

1. Agent: GET /v1/data/weather?lat=10.5&lon=-66.9
2. Server: 402 Payment Required → "Pay $0.008 USDC on Base"
3. Agent: Signs USDC transfer (on-chain)
4. Server: Verifies via Coinbase CDP
5. Server: 200 OK → weather data
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That's it. The agent discovered the API, paid for it, and received data — all without a human writing an email, signing up for an account, or managing a subscription.


The Canary: Real USDC on Base Mainnet

This is the part I'm most proud of. On Sep 10, 2026, I flipped the canary from simulated to real mode.

What happened:

  1. CDP facilitator verified the payment signature
  2. $0.001 USDC settled on Base Mainnet
  3. Volume ticked from 0.620 → 0.621 USDC
  4. The data was returned
# The canary route — real settlement
curl "https://34-156-149-38.sslip.io/aetherapi/v1/data/uuid"
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If it breaks: Non-canary routes stay simulated (fail-open). Zero unguarded routes. The canary can be flipped back to simulated in one line of code.


MCP Discovery: AI Agents Can Find Us

I deployed an MCP (Model Context Protocol) server with SSE transport over HTTPS. AI agents can now discover and use AETHERIUS tools directly.

# See all available tools
curl "https://34-156-149-38.sslip.io/aetherapi/mcp/discovery"

# Connect via SSE
curl "https://34-156-149-38.sslip.io/aetherapi/mcp/sse"

# Health check
curl "https://34-156-149-38.sslip.io/aetherapi/mcp/health"
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10 free x402 tools available via MCP:

  • aetherius_network — Full Base network health
  • aetherius_stablecoins — USDC/USDT/DAI flows
  • aetherius_gas — Gas price analysis
  • aetherius_whales — Large USDC transfers
  • aetherius_sentiment — Fear & Greed + BTC trend
  • aetherius_market_pulse — Real-time market conditions
  • aetherius_base_stats — Chain health snapshot
  • aetherius_telemetry — Live service telemetry
  • aetherius_analytics — Volume and trends
  • aetherius_health — API health

Why this matters: A Claude, Cursor, or LangChain agent can now discover AETHERIUS tools without me having to manually configure anything. The Bazaar manifest (/mcp/discovery) is the entry point.


The 11 API Categories

Maps & Geocoding (5 endpoints)

Business search, nearby places, reverse geocode — all via OpenStreetMap.

curl "https://34-156-149-38.sslip.io/aetherapi/v1/maps/search?q=coffee+shop+CDMX&limit=5" \
  -H "X-PAYMENT: anything"
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Token & Crypto (13 endpoints)

Real-time prices, token analysis, gas oracle, NFT metadata, wallet balances.

curl "https://34-156-149-38.sslip.io/aetherapi/v1/token/price?token=bitcoin" \
  -H "X-PAYMENT: anything"
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Web (7 endpoints)

Scraper, screenshots, DNS, WHOIS, SSL checks, IP geolocation.

curl "https://34-156-149-38.sslip.io/aetherapi/v1/web/ssl?domain=github.com" \
  -H "X-PAYMENT: anything"
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Data (12 endpoints)

Weather, forecasts, air quality, translations, text summarizer, QR codes.

curl "https://34-156-149-38.sslip.io/aetherapi/v1/data/weather?lat=40.71&lon=-74.01" \
  -H "X-PAYMENT: anything"
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DeFi (10 endpoints)

Yield pools, TVL, stablecoin data, DEX volumes, impermanent loss calculator.

curl "https://34-156-149-38.sslip.io/aetherapi/v1/defi/yields" \
  -H "X-PAYMENT: anything"
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Plus: Email, Forex, News, Crypto, Storage

11 categories. 100 endpoints. All live on Base Mainnet.


The 40 FREE Endpoints Nobody Else Has

This is the part I'm most proud of. Nobody else is providing on-chain analytics for the agent economy.

The x402 Intelligence + QuantumXBrain endpoints read USDC transfers directly from Base Mainnet + CoinGecko + DefiLlama. No API key needed. No payment required. Try them right now:

Core Intelligence

# Recent USDC transfers
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/payments/recent"

# Top USDC spenders leaderboard
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/top-agents"

# Network health & trends
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/analytics"
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Chain & Gas

# Chain health snapshot (block, gas, chain ID)
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/base-stats"

# Gas price analysis
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/gas"
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Activity Tracking

# Whale alerts (>$10K transfers)
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/whales"

# Hourly volume breakdown
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/hourly"

# USDC mint/burn activity
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/mint-burn"
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Wallet Intelligence

# Wallet risk score (0-100)
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/risk/0x677B483128D0399bCD0A5AB36eE990C0246d7f61"

# Compare two wallets
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/compare?a=0x677B...&b=0xAc7d..."
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Market Intelligence

# Top USDC-receiving contracts
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/contracts"

# DeFi protocol activity
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/defi-pulse"
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100% free. No signup. No API key. Just call.


The Python SDK (v2.0)

I built a Python SDK with typed sub-clients for all 100 endpoints:

from aetheriusx import AetheriusXClient

# Connects to mainnet by default
client = AetheriusXClient()

# ── FREE x402 Intelligence (no payment needed) ──
stats = client.x402.base_stats()
gas = client.x402.gas()
whales = client.x402.whales()
top = client.x402.top_agents()
risk = client.x402.risk("0x677B...")
history = client.x402.history("0x...")

# ── Paid endpoints (auto-handles 402 challenge) ──
weather = client.data.weather(lat=10.5, lon=-66.9)
price = client.token.price(token="bitcoin")
email_ok = client.email.validate(email="user@example.com")

# ── Catalog browsing ──
print(client.catalog.summary())  # Full 100-endpoint catalog
cheapest = client.discover_cheapest()
free_routes = client.discover_free()
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Install: pip install -e ./sdks/python


Why x402?

The x402 protocol repurposes HTTP status code 402 ("Payment Required") for crypto payments.

Old World (API Keys) New World (x402)
Human signs up Agent pays per request
Gets API key Gets payment challenge
Manages subscription One-time USDC transfer
Hits rate limits No limits
Contacts support Server auto-verifies

The x402 response looks like this:

{
  "error": "Payment required",
  "amount": "0.008",
  "currency": "USDC",
  "network": "eip155:8453",
  "pay_to": "0x677B483128D0399bCD0A5AB36eE990C0246d7f61",
  "route": "/v1/data/weather",
  "hint": "Retry with header 'X-PAYMENT: <payment-proof>'."
}
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The agent reads this, signs a USDC transfer on Base, and retries with the payment proof. The server verifies on-chain via Coinbase CDP and returns the data.

Why USDC on Base?

  • Sub-cent transaction fees
  • Instant settlement
  • Coinbase backing
  • Ethereum security
  • Growing ecosystem

The Tech Stack

Component Technology Purpose
Server FastAPI (Python) High-performance async API
Protocol x402 HTTP 402 + crypto payments
Payments USDC on Base Stablecoin on L2
Verification Coinbase CDP On-chain verification
Hosting GCP Compute Engine Global edge
Process Systemd + Nginx Service management
Dashboard Vanilla JS Zero-build control room
Landing React 19 + Three Fiber + GSAP 3D globe, 20 sections
MCP SSE over HTTPS Agent discovery
SDKs Python + JavaScript Agent integration

What I Learned as a Solo Builder

1. Canary beats "it works on my machine"

Simulated mode proves the flow. Canary proves the economics. The moment I flipped from simulated to real, everything changed. The data I got back was worth more than any test.

2. MCP is the missing piece

AI agents can't use APIs they can't find. MCP discovery (/mcp/discovery) makes AETHERIUS self-describing. Claude, Cursor, or any MCP-compatible client can discover and use the tools without manual configuration.

3. Open source is the best distribution

Every line of code is public. Every transaction is verifiable on-chain. This creates trust no marketing budget can buy.

4. The agent economy is real

AI agents are already consuming APIs. They just need a payment method that works without human intervention.

5. $5.80 is enough to start

No VC. No grants (yet). Just build something useful and ship it.

6. Distribution > Building

I spent 8 days building 100 endpoints. I should have spent 4 days building and 4 days distributing. The hardest part isn't building — it's getting people to use what you built.


Try It Right Now

# Free endpoints — no API key needed
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/base-stats"
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/gas"
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/whales"
curl "https://34-156-149-38.sslip.io/aetherapi/v1/x402/top-agents"
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MCP Discovery:

curl "https://34-156-149-38.sslip.io/aetherapi/mcp/discovery"
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Interactive playground: wilnowilx.github.io/aetheriusxapi/

Dashboard: wilnowilx.github.io/aetheriusxapi/dashboard/


What's Next

  • Expand to 120+ endpoints with grant funding
  • MCP tools expansion — more free tools for agent discovery
  • SDK releases for Go and Rust
  • Third-party API provider onboarding
  • 500M+ Spanish-speaking developers included via bilingual docs

Links


Built by a solo developer from Venezuela 🇻🇪. No bank account. No PayPal. No LinkedIn. Only a crypto wallet. The limit is not money. The limit is imagination.

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