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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 — 80 Endpoints in 4 Days, Solo.

#api #crypto #ai #opensource

Description: "AETHERIUS is an open-source API marketplace where AI agents pay per request in USDC on Base. No accounts. No API keys. No subscriptions. Just wallets and code."
tags: apis, crypto, ai,opensource
Series: "Building the Agent Economy"

TL;DR: I built AETHERIUS — an open-source API marketplace where AI agents pay per request in USDC on Base Mainnet. No accounts. No API keys. No subscriptions. 80 live endpoints. Python + JavaScript SDKs. All verifiable on-chain. Built solo in 4 days with $5.80 in ETH.

🚀 Try it now: curl http://34.156.149.38/aetherapi/v1/x402/base-stats

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 80
Paid endpoints 60 ($0.001–$0.03/call)
FREE endpoints 20 (x402 Intelligence — on-chain analytics)
Payment currency USDC on Base Mainnet
Build time 4 days
Total capital $5.80 ETH
Team size 1 (me)
Tests 60/60 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 11 API Categories

Maps & Geocoding (5 endpoints)

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

curl "http://34.156.149.38/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 "http://34.156.149.38/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 "http://34.156.149.38/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 "http://34.156.149.38/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 "http://34.156.149.38/aetherapi/v1/defi/yields" \
  -H "X-PAYMENT: anything"
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Plus: Email, Forex, News, Crypto, Storage

11 categories. 80 endpoints. All live on Base Mainnet.

The 20 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 endpoints read USDC transfers directly from Base Mainnet. No API key needed. No payment required. Try them right now:

Core Intelligence 

# Recent USDC transfers
curl "http://34.156.149.38/aetherapi/v1/x402/payments/recent"

# Top USDC spenders leaderboard
curl "http://34.156.149.38/aetherapi/v1/x402/top-agents"

# Network health & trends
curl "http://34.156.149.38/aetherapi/v1/x402/analytics"
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Chain & Gas 

# Chain health snapshot (block, gas, chain ID)
curl "http://34.156.149.38/aetherapi/v1/x402/base-stats"

# Gas price analysis
curl "http://34.156.149.38/aetherapi/v1/x402/gas"
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Activity Tracking 

# Whale alerts (>$10K transfers)
curl "http://34.156.149.38/aetherapi/v1/x402/whales"

# Hourly volume breakdown
curl "http://34.156.149.38/aetherapi/v1/x402/hourly"

# USDC mint/burn activity
curl "http://34.156.149.38/aetherapi/v1/x402/mint-burn"
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Wallet Intelligence 

# Wallet risk score (0-100)
curl "http://34.156.149.38/aetherapi/v1/x402/risk/0x677B483128D0399bCD0A5AB36eE990C0246d7f61"

# Compare two wallets
curl "http://34.156.149.38/aetherapi/v1/x402/compare?a=0x677B...&b=0xAc7d..."
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Market Intelligence 

# Top USDC-receiving contracts
curl "http://34.156.149.38/aetherapi/v1/x402/contracts"

# DeFi protocol activity
curl "http://34.156.149.38/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 80 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 80-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
SDKs Python + JavaScript Agent integration

What I Learned as a Solo Builder

1. Solo builders can move 10x faster than teams

No meetings. No approvals. No architecture debates. Just build, ship, iterate.

2. 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.

3. The agent economy is real

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

4. $5.80 is enough to start

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

5. Distribution > Building

I spent 4 days building 80 endpoints. I should have spent 2 days building and 2 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 "http://34.156.149.38/aetherapi/v1/x402/base-stats"
curl "http://34.156.149.38/aetherapi/v1/x402/gas"
curl "http://34.156.149.38/aetherapi/v1/x402/whales"
curl "http://34.156.149.38/aetherapi/v1/x402/top-agents"
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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
  • SDK releases for Go and Rust
  • Third-party API provider onboarding
  • Multi-chain support (Ethereum, Polygon, Arbitrum)
  • 500M+ Spanish-speaking developers included via bilingual docs

Links

Resource URL
GitHub github.com/wilnowilx/aetheriusxapi
Live API 34.156.149.38/aetherapi
Dashboard wilnowilx.github.io/aetheriusxapi/dashboard/
Twitter @aetheriusxAPI
Telegram @aetherius_xAPI
YouTube Demo video

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.

If this resonates:

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