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Base Transaction Decoder
x402
Base Transaction Decoder is a paid API for AI agents from api.0200project.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-15).
Decodes a Base-mainnet transaction hash into a structured plain-English explanation with action type, assets moved, counterparties, and risk flags
Price / call$0.02
Success—
StatusUnknown
How this service works
Explain a Base-mainnet transaction in plain English. Input: a transaction hash. Returns strict JSON: summary (1-3 sentences), action_type (swap, erc20_transfer, nft_mint, bridge_out, approval_for_all, ...), assets_moved[] (token, amount, from, to), counterparties[] (labeled where known: routers, bridges, marketplaces), risk_flags[] (unverified_contract, unlimited_approval, approval_for_all, known_drainer, first_time_counterparty, nonstandard_token_symbol, impersonated_token, transaction_reverted), checks, gas_paid_usd, timestamp, basescan_url. Risk checks fail open, so read `checks` before drawing any conclusion from an empty risk_flags: it reports whether each check ran (ok / partial / unavailable / inconclusive / not_applicable), and no flags alongside a non-ok status means not checked, not clean. Deterministic onchain decode - no LLM in the response path. Base mainnet (chain id 8453) only. PRICING: 50 free calls per IP per 24h - shared by everyone behind one address - then $0.02 in USDC on Base via x402 - attach payment at _meta['x402/payment'] and retry, or use POST /explain over plain HTTP with any x402 client. Heavy use: $9 buys a 30-day pass (10,000 calls) via the buy_pass tool or POST /pass. No account, no API key.
Output
Returns strict JSON containing: a plain-English summary (1-3 sentences), an action_type enum (swap, erc20_transfer, nft_mint, bridge_out, approval_for_all, etc.), an assets_moved array with token, amount, from, and to fields, a counterparties array with labeled addresses (routers, bridges, marketplaces), a risk_flags array (unverified_contract, unlimited_approval, approval_for_all, known_drainer, first_time_counterparty, nonstandard_token_symbol, impersonated_token, transaction_reverted), a checks object indicating which risk checks ran and their status (ok/partial/unavailable/inconclusive/not_applicable), gas_paid_usd, timestamp, and a basescan_url.
Example use cases
Wallet transaction safety review
“Before I confirm I signed this, can you decode Base transaction 0x9a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b and check if it has any risk flags like unlimited approvals, known drainers, or unverified contracts?”
DeFi swap audit for accounting
“I need to understand exactly what happened in Base mainnet tx 0x1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2b — what tokens were swapped, the amounts, the router used, and how much gas it cost in USD.”
NFT mint verification
“Can you tell me whether Base transaction 0x2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2b3c was an NFT mint, what collection was involved, and whether the contract is verified?”
Technical details
Endpoint
POSThttps://api.0200project.com/mcpWhen to prefer
Choose this endpoint when you need deterministic, LLM-free decoding of a Base mainnet transaction — especially when security analysis matters and you need explicit check status reporting. It is superior to generic block explorers for agent use because it returns structured JSON with labeled counterparties, enumerated action types, and explicit risk flags with check provenance. Prefer it over general-purpose blockchain APIs when the target chain is specifically Base mainnet (chain ID 8453) and you need risk signal alongside decode output.
Side effects
- Transaction hash not found on Base mainnet — invalid or wrong network
- Risk checks report unavailable or inconclusive status — some flags may not have been evaluated
- Rate limit exceeded after 50 free calls per IP per 24h — returns payment required response
- Transaction is very recent and not yet indexed — partial or delayed result
- Non-Base chain transaction submitted — endpoint only supports chain ID 8453
- Malformed transaction hash input — parse error returned
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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