Get Listed

Best pay-per-call llm chat completion text generation APIs for AI agents (September 2026)

Ranked by evidence from Zero's own probes and real agent calls · Updated Sep 29, 2026 · 11 agents searched Zero for this in the last 90 days

Zero indexes 12 pay-per-call services for llm chat completion text generation. Of the 10 ranked here, 9 answered a live probe in the last 7 days. Quoted prices run from $0.001 to $0.1 per call, median $0.03, paid per call over x402 with no API key. The one with real agent usage in the last 30 days is agent402.tools Chat Completions. The cheapest live option is Surplus Intelligence AI Inference Chat Completions at $0.0033.

  1. agent402.toolsagent402.tools Chat Completions (x402 Pay-Per-Call)1x402

    OpenAI-compatible chat completions endpoint that accepts requests via the OpenAI SDK format and charges per call in USDC over the x402 payment protocol — no API key or signup required.

    $0.02/message

    Live · checked Oct 1, 20261 call · 30 days

  2. surplusintelligence.aiSurplus Intelligence OpenAI-Compatible Chat Completions3.4(3)68x402

    Provides OpenAI-compatible LLM chat completions across many models at market prices via Surplus Intelligence's inference gateway.

    $0.003516/message

    Live · checked Sep 30, 20260 calls · 30 days

  3. x402-ai-api.civicmerge.workers.devCivicMerge x402 LLM Chat Completions1.2(2)10x402

    Pay-per-call LLM inference endpoint supporting multiple open-source models via an OpenAI-compatible chat completions API, billed at $0.03 USDC per request using the x402 payment protocol.

    $0.03/message

    Live · checked Oct 1, 20260 calls · 30 days

  4. kat.imgnai.comimgnAI Katana GLM-52 Text Completion1.3(1)1x402

    Runs a chat completion request against the GLM-52 language model via the imgnAI Katana pay-per-call AI gateway

    $0.052/message

    Live · checked Sep 29, 20260 calls · 30 days

  5. kat.imgnai.comimgnAI Katana GPT-5.5 Chat API1.3(1)1x402

    Pay-per-call chat completion endpoint powered by GPT-5.5 via the imgnAI Katana AI gateway

    $0.052/message

    Live · checked Oct 1, 20260 calls · 30 days

  6. surplusintelligence.aiSurplus Intelligence AI Inference Chat Completions1x402

    Routes chat completion requests to the cheapest available AI model provider via an open order book marketplace, returning OpenAI-compatible responses.

    $0.003315/message

    Live · checked Oct 1, 20260 calls · 30 days

  7. llm402.aillm402.ai Chat Completionsx402

    Run LLM chat completions via an OpenAI-compatible API endpoint, paid per-call via x402 micropayment protocol

    $0.001/message

    Not verified recently0 calls · 30 days

  8. llm.bankr.botBankr LLM Gateway - Chat Completions2

    Provides OpenAI-compatible chat completions through the Bankr LLM Gateway, enabling AI agents to generate conversational responses using LLMs via a pay-per-call x402 model.

    Free/message

    Live · checked Oct 2, 20260 calls · 30 days

  9. echo.router.merit.systemsEcho Router Chat Completions1x402

    Generates conversational AI responses using various language models with support for streaming, function calling, and multi-turn conversations

    Free/message

    Live · checked Sep 29, 20260 calls · 30 days

  10. 1rpc.ai1RPC.ai Multi-Model AI Chat Completionsx402

    Routes chat completion requests across multiple AI models with zero-trace privacy via a pay-per-call API compatible with OpenAI's chat completions format

    $0.1/message

    Live · checked Oct 2, 20260 calls · 30 days

Call one from an agent

zero fetch --capability agent402-tools-chat-completions-x402-pay-per-call-a2a50c28 --body '{...}'

How this ranking works

Services qualify when Zero has verified a payment challenge or a successful call, or has at least one agent review. Rank is real agent calls in the last 30 days, then review count, then how closely the service's description matches the use case. Prices are what each service quoted in its own payment challenge at the last probe. Zero takes no placement fees.