store.kv-put

STORE: persist a JSON value under a key, scoped to YOUR wallet (the x402 payer). Key/value store with retrieval — set a value once, read it back later with store.kv-get or list with store.kv-scan. Data is private to your wallet and kept on a rolling 90-day window that resets every time you touch the object. Use a namespace (ns) to group related keys. Value up to 1 MB; no per-wallet total cap. No account or API key — pay per call with x402 and your data is keyed to your payer address.

Overview

The kv put API is a pay-per-call store endpoint built for AI agents and autonomous software. STORE: persist a JSON value under a key, scoped to YOUR wallet (the x402 payer).

There is no signup and no API key. An agent (or any HTTP client) hits the endpoint, receives an x402 "402 Payment Required" challenge, signs a sub-cent USDC payment on Base or Solana, and retries — the data comes back on the paid request. That makes it a drop-in kv put data source for an agent tool-use loop, an MCP host, or a backend that needs store data on demand without onboarding to yet another vendor portal.

Use cases

• Give an AI agent live kv put lookups as a tool, with no API key to provision or rotate — the agent pays per call from a wallet you fund.
• Enrich records in a data pipeline with store data, paying only for the calls you actually make instead of a monthly seat.
• Ground LLM answers in authoritative store data to cut hallucination, then optionally request a signed response for verifiability.
• Prototype against the live kv put API in minutes using the free trial call, then flip to per-call x402 payment for production with no code change.

Parameters

Code samples

# 1. Probe the endpoint with no auth — receive 402 with PaymentRequirements
curl -sS -X POST 'https://2s.io/api/store/kv-put' \
  -H 'Content-Type: application/json' \
  -d '{"ns":"example","key":"example"}'

# 2. Sign the EIP-3009 transferWithAuthorization for the advertised price +
#    payTo from the 402 envelope, then retry with PAYMENT-SIGNATURE:
curl -sS -X POST 'https://2s.io/api/store/kv-put' \
  -H 'Content-Type: application/json' \
  -H 'PAYMENT-SIGNATURE: <base64-json-payload>' \
  -d '{"ns":"example","key":"example"}'

# Or just use the canonical runner — it handles the whole loop:
#   EVM_PRIVATE_KEY=0x... node --env-file=.env.local \
#     --experimental-strip-types scripts/x402-pay.ts \
#     'https://2s.io/api/store/kv-put'

import { TwoS } from '@2sio/sdk'

const client = new TwoS({
  privateKey: process.env.EVM_PRIVATE_KEY as `0x${string}`,
})

const result = await client.store.kvPut({
  "ns": "example",
  "key": "example"
})

console.log('endpoint:', result.endpoint)
console.log('cost:', result.costUsd, 'USDC')
console.log('tx:', result.settlement?.txHash)
console.log('data:', result.data)

import os
from twosio import TwoS

client = TwoS(private_key=os.environ["EVM_PRIVATE_KEY"])

result = client.store.kv_put(ns="example", key="example")

print("endpoint:", result.endpoint)
print("cost:", result.cost_usd, "USDC")
print("tx:", (result.settlement or {}).get("tx_hash"))
print("data:", result.data)

// 1. Add @2sio/mcp to your MCP host config (Claude Desktop example below).
//    EVM_PRIVATE_KEY funds x402 payments per call.

// claude_desktop_config.json
{
  "mcpServers": {
    "2sio": {
      "command": "npx",
      "args": ["-y", "@2sio/mcp"],
      "env": { "EVM_PRIVATE_KEY": "0x..." }
    }
  }
}

// 2. Once the server is running, agents call this tool via standard MCP:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "store.kv-put",
    "arguments": {
      "ns": "example",
      "key": "example"
    }
  }
}

Response

{
  "ok": true,
  "items": [
    {
      "key": "example",
      "bytes": 1,
      "expiresAt": "example"
    }
  ],
  "total": 1,
  "source": {
    "provider": "example",
    "url": "example",
    "license": "example"
  }
}

FAQ

Do I need an API key to use the kv put API?

No. store.kv-put is x402-native — there is no signup and no API key. Your client makes the call, receives a 402 with payment requirements, signs a USDC payment, and retries. Funds come from a wallet you control.

How much does the kv put API cost?

$0.0020 USDC per call, charged per request. There are no monthly fees, seats, or minimums — you pay only for the calls you make.

Can I try the kv put API for free first?

Yes. Add ?trial=1 (or the header X-2s-Trial: 1) to get a free real call per endpoint per hour, so you can verify the response shape before wiring payment.

Which networks and tokens are supported?

USDC on Base (via EIP-3009 transferWithAuthorization) or Solana (SPL transfer), using the open x402 payment protocol.

How do I call store.kv-put from an AI agent or MCP host?

Use @2sio/sdk (TypeScript), 2sio (Python), or the @2sio/mcp server for any MCP host — each handles the probe → sign → retry loop for you. See the code samples on this page.

Discovery

• /api/directory — full catalog of every endpoint
• /openapi.json — OpenAPI 3.1 spec (per-op x-payment-info, x402Payment security)
• /.well-known/x402 — machine-readable service descriptor for x402-aware crawlers
• /.well-known/mcp/server-card.json — MCP SEP-1649 server card
• /llms.txt — plain-text manifest for LLM ingestion