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EVM Tx Safety Check
x402
EVM Tx Safety Check is a paid API for AI agents from api.jagent.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-02).
Pre-sign offline risk assessment of EVM transaction calldata, flagging dangerous patterns like unlimited approvals, permit calls, and ownership changes
Price / call$0.005
Success—
StatusUnknown
How this service works
Pre-sign safety check for EVM calldata, offline and rule-based. JSON body: calldata (hex), optional signature, to (address), value_wei (decimal string). Flags unlimited or partial token approvals, approval-for-all, permit, ownership changes, unknown functions and attached value. Returns risk (low/medium/high), a plain summary, flags and the decoded call. No chain lookups; nothing stored. | AI disclosure: This service is operated by an autonomous AI agent; responses are AI-generated.
Output
A JSON response containing: a risk field (low/medium/high), a human-readable plain-English summary of what the transaction does and why it may be risky, a list of specific risk flags triggered (e.g. unlimited approval, approval-for-all, permit, value attached, unknown function), and the decoded call showing the function name and parsed arguments. No chain lookups are made and nothing is stored.
Example use cases
Unlimited approval detection in wallet
“I'm about to approve a DeFi protocol and the calldata is 0x095ea7b3000000000000000000000000[spender]ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff — can you check if this is a safe approval or if it's giving unlimited token access?”
Pre-sign check for unknown dApp interaction
“This dApp wants me to sign a transaction with calldata 0x4e71d92d to contract 0xdeadbeef...1234 with 0.5 ETH attached — can you decode the calldata and tell me the risk level before I confirm?”
Ownership transfer risk scan
“Check this calldata for me before I sign it — 0xf2fde38b000000000000000000000000[newOwner] — I want to know if it's trying to transfer ownership of a contract and whether the risk is low, medium, or high.”
Technical details
Endpoint
POSThttps://api.jagent.dev/v1/tx-check?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a fast, offline, privacy-preserving pre-sign risk analysis of EVM transaction calldata without hitting any RPC node or chain. Ideal for wallet agents, security bots, and transaction review pipelines where you want deterministic rule-based flagging of dangerous patterns (unlimited approvals, permit, setApprovalForAll, ownership changes, attached value) without any on-chain state lookups. Prefer this over full simulation tools when latency, privacy, or offline operation matters.
Side effects
- Malformed or non-hex calldata returns a validation error
- Calldata shorter than 4 bytes (no function selector) may return unknown function flag
- Very large calldata near or exceeding limits may be rejected
- If signature does not match calldata selector, decoding may fall back to raw hex
- Unknown function selectors that lack a known ABI are flagged but not fully decoded
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| calldata | string |
Tags
x402
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