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Wrap the standard openai.OpenAI client with per-chain private keys. When the server responds with HTTP 402, the library automatically signs and retries the request — zero code changes needed.

Supplying evm registers both exact and upto. svm and tvm register exact only. Default spend controls from x402 cap each payment at $1 of a recognized default asset.

Installation

pip install 'x402-openai[evm]'          # EVM (Ethereum / Base / …)
pip install 'x402-openai[svm]'          # Solana
pip install 'x402-openai[tvm]'          # TVM (TON)
pip install 'x402-openai[all]'          # all chains

Quick Start

from x402_openai import X402OpenAI

client = X402OpenAI(evm="0x…")

res = client.chat.completions.create(
    model="openai/gpt-4o-mini",
    messages=[{"role": "user", "content": "Hello!"}],
)
print(res.choices[0].message.content)

Pass svm="base58…" instead of evm to pay on Solana — the rest of the API is identical. The same constructor accepts tvm.

Usage

Streaming

from x402_openai import AsyncX402OpenAI

client = AsyncX402OpenAI(evm="0x…")

stream = await client.chat.completions.create(
    model="openai/gpt-4o-mini",
    messages=[{"role": "user", "content": "Explain x402"}],
    stream=True,
)

async for chunk in stream:
    if chunk.choices and chunk.choices[0].delta.content:
        print(chunk.choices[0].delta.content, end="")

Multi-chain

client = X402OpenAI(
    evm="0x…",
    svm="base58…",
    tvm="hex-or-base64…",
)

The protocol selects the right chain automatically based on the server's payment requirements.

Key formats

Option	Key material
evm	0x hex secp256k1
svm	base58 64-byte secret
tvm	hex/base64 32-byte seed or 64-byte secret

Bare evm / svm / tvm strings become { private_key }. Empty strings throw. Config objects are EvmConfig / SvmConfig (private_key, optional rpc_url) and TvmConfig (private_key, optional network / provider / api_key / provider_base_url).

TVM

TVM registers exact only on a concrete CAIP-2. Default network is tvm:-239 (or pass network="tvm:-3"). The client never registers tvm:* — the signer is bound to one network.

• Hex/base64 32-byte seed or 64-byte secret, or TvmConfig(private_key, network?, provider?, api_key?, provider_base_url?).
• The 402 must set extra.areFeesSponsored is True.
• Default asset is USDT jetton; native TON is not a default asset — pass spend_controls.allowed_assets to allow it.

Long-lived TVM clients hold ExactTvmScheme HTTP clients. Call client.close() (sync) or await client.aclose() (async) when finished. close() before the first request is a no-op. A request after close() raises X402OpenAI is closed and does not rebuild.

Spend controls

x402Client() / x402ClientSync() already allow only default (USD-pegged) assets and cap each payment at $1. This package does not change that default.

Pass spend_controls to raise the cap, allow extra assets, or disable controls:

client = X402OpenAI(
    evm="0x…",
    spend_controls={"max_amount_per_payment": "$5"},
)

• Omit spend_controls to keep the official $1 + default-asset allowlist.
• spend_controls=False disables allowlist and caps.
• Gateway prices above $1 require the caller to raise max_amount_per_payment.

exact and upto

evm registers ExactEvmScheme and UptoEvmScheme on eip155:*. svm registers ExactSvmScheme on solana:* (no Python upto). tvm registers ExactTvmScheme on the configured CAIP-2. No extra flag; the gateway is not probed.

• EVM upto: Permit2 (permitWitnessTransferFrom). The 402 must include extra.facilitatorAddress. Pass { rpc_url } on evm to enable official EIP-2612 / ERC-20 approval sponsoring. The 402 amount is the authorized maximum; the client signs that max (the server may charge <= max at settle). If the ceiling exceeds spend controls, payment creation throws.
• SVM exact: the 402 must include extra.feePayer. There is no SVM upto scheme in Python x402.

from x402_openai import X402OpenAI, prefer_scheme

client = X402OpenAI(
    evm="0x…",
    policies=[prefer_scheme("upto")],
)

prefer_scheme("upto") only affects chains that registered upto (EVM). An SVM-only client still pays exact.

Payment Policies

Use policies to prefer a chain or scheme when multiple options remain after spend controls. Policies do not cap spend.

from x402_openai import X402OpenAI, prefer_network, prefer_scheme

client = X402OpenAI(
    evm="0x…",
    svm="base58…",
    policies=[
        prefer_network("eip155:8453"),  # Prefer Base mainnet
        prefer_scheme("upto"),
    ],
)

If nothing matches, all remaining options pass through. If any upto requirement remains, prefer_scheme("upto") keeps only those (EVM); otherwise the list passes through and SVM can pay exact.

Closing

client.close()          # X402OpenAI
await client.aclose()   # AsyncX402OpenAI

close() / aclose() dispose TVM ExactTvmScheme HTTP clients. Close before the first request is a no-op. A request after close raises X402OpenAI is closed and does not rebuild.

API Reference

X402OpenAI / AsyncX402OpenAI

Drop-in replacement for openai.OpenAI / openai.AsyncOpenAI. Provide at least one of evm, svm, tvm, or x402_client:

Parameter	Type	Description
evm	str or EvmConfig	EVM secp256k1 private key (0x hex). Registers exact and upto on eip155:*.
svm	str or SvmConfig	Solana base58 secret key. Registers exact only on solana:*.
tvm	str or TvmConfig	TON seed/secret. Registers exact on tvm:-239 by default (tvm:-3 if set). Never tvm:*.
spend_controls	SpendControls or False	Official spend controls. Omit for $1 + default assets.
policies	list[Policy]	Preference policies (prefer_network / prefer_scheme).
payment_requirements_selector	Selector	Picks among remaining requirements after spend controls and policies.
x402_client	x402ClientSync / x402Client	Pre-configured core x402 client (exclusive with keys, spend_controls, policies, payment_requirements_selector).

Type	Fields	Notes
EvmConfig	{ private_key, rpc_url? }	rpc_url enables EIP-2612 / ERC-20 approval sponsoring
SvmConfig	{ private_key, rpc_url? }	rpc_url is Solana JSON-RPC
TvmConfig	{ private_key, network?, provider?, api_key?, provider_base_url? }	network is tvm:-239 or tvm:-3

Empty keys throw.

close() / aclose() release TVM handles. Close before the first request is a no-op. A request after close raises X402OpenAI is closed and does not rebuild.

SpendControls is the official snake_case TypedDict from x402.

All standard OpenAI options (base_url, timeout, max_retries, …) are forwarded. Default base_url: https://llm.qntx.org/v1. api_key defaults to "x402". http_client is not accepted.

Option	Chain	Install extra
evm	EVM	x402-openai[evm]
svm	Solana	x402-openai[svm]
tvm	TVM	x402-openai[tvm]

License

This project is licensed under the MIT License.

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