presign-guard

Safe to sign? Green/orange/red verdict for EVM, Solana, XRPL and Algorand transactions, permits, EIP-7702 and tokens, plus OFAC wallet screening.

View on fizzl.eu

Hosted MCP Server

npx add-mcp 'https://presign-guard.fizzl.eu/mcp'

Installs into Claude Code, Codex, Cursor and more

Documentation

Check it before your agent signs it.

Send presign-guard the transaction, approval or signature your agent is about to sign. You get back green, orange or red, with the reasons, in under a second. EVM chains, Solana, the XRP Ledger and Algorand. $0.01 per check in USDC via x402. No account, no API key.

$0.01 per check $0.80 for 100 prepaid · 20% off $7.00 for 1000 prepaid · 30% off

Try it

You pay in USDC on Base. Your wallet shows a signature for exactly this amount, to our payout wallet 0x6B0F…5F25. MetaMask's security check may call that wallet "untrusted" because it is a regular wallet rather than a contract; that is normal for x402 payments, and the signature can only move this one amount, once.

See it in 90 seconds

Watch the explainer video

New: is this wallet sanctioned? In 60 seconds

Watch the wallet screen video

The token verdict in 45 seconds

Watch the token verdict video

How agents use it

HTTP + x402

POST /v1/check answers 402 with the price; the agent pays and gets the verdict in the same request.

What it reads

Approvals, raw transactions, and EIP-712 signatures: Permit, Permit2, Seaport and x402 payments (EIP-3009). It checks who gets access and the token itself: honeypots, fake look-alikes and high taxes.

Solana, XRPL & Algorand

type: "solana": decoded, then simulated. type: "xrpl": a new regular key or fake RLUSD is red, issuing a credential to someone else orange. type: "algorand": a rekey, a close to someone else or fake USDC is red; simulated. Solana agents

Token verdict

GET /v1/token?chain=solana&address=…, $0.01 on Base, Solana, the XRP Ledger, Algorand or Stellar: before buying or accepting a token, a grade (SAFE to AVOID), reasons like active mint or freeze authority, unlocked LP, thin liquidity or a few big holders, and market data. Solana, Base, Ethereum, the XRP Ledger, Algorand and more.

Approval audit

GET /v1/approvals?chain=base&address=…, $0.02 on Base, Solana, the XRP Ledger, Algorand or Stellar: every open token approval of a wallet, who the spender is (flagged, a plain wallet, unverified, unlimited), and which ones to revoke. Base, Ethereum and more, and Solana (token delegations).

Wallet screen

GET /v1/screen?address=…, $0.01: is this wallet sanctioned? Any chain's address (EVM, Solana, Tron, Bitcoin, the XRP Ledger, Algorand) against the OFAC SDN list, synced from the US Treasury, plus theft and phishing reports for EVM. Before paying someone, or accepting their money.

For sellers

Don't take money from sanctioned wallets. presign-guard-payer-screen is one Express middleware before your x402 paywall: a payer on the OFAC SDN list gets 451 and is never charged (EVM, Solana, Algorand, XRP Ledger). It screens in memory against GET /v1/sanctions, our free open copy of the list.

Prepaid credits

Checking often? One payment of $0.80 buys 100 checks, $7.00 buys 1000 (20% / 30% off), valid a year. GET /v1/credits/100 returns a key; send it as x-credit-key instead of paying per call. Prices and costs · the presign-guard-wallet package uses it with creditKey.

Signed verdicts

Every paid answer carries a receipt signed by our published signer (EIP-191 over canonical JSON, bound to your request), so an agent can prove later which verdict it got, not only that it paid. POST /v1/verify checks one for free.

Discovery

OpenAPI, /.well-known/x402 and the CDP Bazaar.

Questions

How do I check a transaction before an AI agent signs it?

Send it to presign-guard: POST https://presign-guard.fizzl.eu/v1/check with the transaction, approval, typed-data signature or message. For $0.01 it answers green, orange or red with reason codes: known drainers, sanctioned addresses, unlimited approvals, look-alike tokens and a simulation of what the transaction does. On red, don't sign. Errors are never charged.

Which chains does presign-guard support?

EVM chains (Ethereum, Optimism, BNB Chain, Polygon, Base and Arbitrum), Solana, the XRP Ledger and Algorand. Paid calls accept USDC on Base, Solana, Algorand or Stellar, RLUSD on the XRP Ledger, or MPP.

Is there an API to screen a wallet against the OFAC sanctions list?

Yes: GET https://presign-guard.fizzl.eu/v1/screen?address=<address> screens any chain's address against the US Treasury's OFAC SDN list for $0.01, plus theft and phishing reports for EVM addresses. The whole list is free open data at GET https://presign-guard.fizzl.eu/v1/sanctions, refreshed from the Treasury every 6 hours.

How do I check a token before an agent buys it?

GET https://presign-guard.fizzl.eu/v1/token?chain=base&address=<token> gives a grade with reasons (honeypot and rug-pull signs, look-alike tokens, mint and freeze authority, liquidity) and market data for $0.01. It works for tokens on Base, Solana and Algorand.

Can an AI agent use presign-guard without an account or API key?

Yes. Each paid call is paid per use over x402 or MPP, with no account. The MCP server at https://presign-guard.fizzl.eu/mcp has free tools (presign_quick_check and token_quick_verdict) to try first, and the Fizzl Agent Wallet runs a presign-guard check on every signature it makes.

How do I add presign-guard to Claude or Cursor?

Add the remote MCP server https://presign-guard.fizzl.eu/mcp. In Claude Code: claude mcp add --transport http presign-guard https://presign-guard.fizzl.eu/mcp. Agent skills: npx skills add Fizzl13/presign-guard, or in Claude Code /plugin marketplace add Fizzl13/x402-doctor and then /plugin install presign-guard@fizzl.