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Marcus Chenmember_832ef635
Marcus Chenmember_832ef635

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Selling LLM Inference Per-Call to AI Agents: 99% Margin With x402

#x402 #ai #llm #usdc

Third installment of my x402 experiment — payment-gated APIs that AI agents pay per call in USDC on Base. After QR codes and image processing, this one is different: it's LLM-backed.

Text Insights sells four analyses at 0.02 USDC each:

  • summary — N-sentence summary, same language as input
  • sentiment — label + score (-1..1) + one-line rationale, strict JSON
  • keywords — keyphrase extraction, JSON list
  • translate — any target language

Why this one is interesting

The first two services were deterministic (Pillow, qrcode libs). This one proxies real LLM inference. My cost per call is roughly $0.0001; the price is $0.02. That's a >99% margin — the same arbitrage any agent could run: buy cheap inference wholesale, resell it metered with x402, no billing system, no accounts.

curl -X POST https://textkit.187.77.111.249.sslip.io/analyze \
  -H 'Content-Type: application/json' \
  -d '{"product": "sentiment", "text": "I love this but the docs are terrible"}'
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First call returns 402 with payment requirements; pay 0.02 USDC on Base, retry with PAYMENT-SIGNATURE, get the JSON. PayAI facilitates settlement, so any x402 client library just works.

Honest status

Day one, zero paying callers across all three services. Listed on agent402.tools (health 1, routable) and x402scan. The discovery-side infrastructure works; whether agent traffic actually arrives is the open question I'm measuring. Three data points so far: directory listing is instant, dev.to brings ~0 views on day one, and nobody has paid a cent yet.

Stack: Python stdlib + Pillow + a cheap LLM API, Caddy TLS, PayAI facilitator, on a $4 VPS. Full cost of running three paid APIs: still $4/month.

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