x402 Endpoint Checks Compared: Six Ways to Look Before Your Agent Pays

Search "check an x402 endpoint before paying" and you get at least six answers. One is ours. They answer different questions, and one charges a fifth of our price per call.

Here are all six, from each tool's own pages as of October 27, 2026. Every fact links to its source. Anything we couldn't confirm is marked and left out.

The question each tool answers

"Check before you pay" covers three different jobs:

1. Do the live terms match the listing? Probe unpaid and compare the 402's wallet, network, token and price with the catalog.
2. Is the endpoint healthy over time? Probe on a schedule and alert on change.
3. Is this seller trustworthy? Score the host or wallet from history, on-chain data or test purchases.

The six, one at a time

402xAgent (ours)

• What it checks: one unpaid probe, then the live 402 against the listing on payTo, network, token (canonical USDC) and price. Answer: pay, skip (with a reason code) or recheck, by public rules.
• Networks: the check reads target payment terms on Base and Solana (OpenAPI spec), but 402xAgent itself is paid only in USDC on Base (pricing).
• Price: 5 free live checks per client per UTC day, free dry runs, then a flat $0.02 USDC per check on Base (pricing).
• Proof: every new receipt is ed25519-signed; the key is at /.well-known/402xagent-keys.json (docs). Free checks too: the free receipt we pulled today verified.
• History: each check reports observations, stable_for_days, a drift flag, pay_to_changed and a 30-day count of term changes. A host reputation band is free at /reputation/<host>. Which term changed, and when, is a separate $0.05 report (docs).
• Wrapper: x402-spotcheck (MIT, npm 1.6.1) wraps @x402/fetch or @x402/axios; a skip blocks the payment.

PulseFeed

• What it checks: /trust covers "liveness, uptime/reputation, a scam & anomaly scan (payTo hijack, price bait-and-switch, honeypot, non-USDC asset), on-chain receiver profile, and a pay/avoid verdict" (pulsefeed.dev). Scoring is documented in its methodology.
• Price: cached /verify is free. Live /trust is $0.004; /trust/history is $0.008, in USDC on Base (pricing).
• History: /trust/history returns "uptime, payTo & price change history, trend" (llms.txt).
• Networks: its risk flags are "network-aware (EVM and Solana)" (methodology), and its receiver check looks for USDC on Base or Solana (Trust Score). PulseFeed itself is paid in USDC on Base (pricing).
• Proof: daily manifests are Ed25519-signed (pulsefeed.dev). Its pages don't say whether each /trust answer is signed.

Lumière PayCheck

• What it checks: endpoints from the x402 Bazaar every 30 minutes for "uptime, response time, price, payout wallet, and network," plus test payments to confirm delivery, graded A to F (features).
• Price: the free POST /v1/check-payment needs no account and returns allow: true/false with reasons, as "advice: your agent can ignore it." Enforced authorization needs a plan: Builder $9/month, Business $49/month (quickstart). Free routes allow 60 requests a minute (home).
• Proof: paid authorization returns an "Ed25519 receipt bound to the URL, amount, and wallet"; the free check has none (quickstart). An allow receipt lasts 5 minutes (integration).
• History: "Wallet and price change alerts" (features).
• Networks: it makes its test payments "on Base and Solana" (features), and its paid routes accept USDC on Base or Solana at the same price (integration). Plans can also be paid monthly by card (home).

TOLLkit Weigh Station

• What it checks: one unpaid request, reporting "the live price, the network, and the wallet the money goes to," with a warning if the wallet differs from the listing (Weigh Station). It compares against the Coinbase Bazaar listing and "does not score or recommend" (llms.txt).
• Price: free, no key: "we don't charge you" (Weigh Station). Seller-side monitoring is "$5 per endpoint, per 30 days," paid in USDC, with "a signed webhook when something changes" (Weigh Station).
• Networks: the check reports each endpoint's network (Weigh Station), but its pages don't list which networks it reads. TOLLkit's own paid tools take USDC on Base or Solana (llms.txt).
• Proof: its pages don't say whether check results are signed.

Sentinel

• What it checks: a monitor, not a per-call check. The agent payment check is a sub-check on an HTTP monitor that "never pays," parses x402 v1, x402 v2 or MPP envelopes, can assert an expected amount, network and pay-to address, and opens an incident on a mismatch (docs). It probes from fifteen regions (product page).
• Price: Free plan: 10 monitors at a 5-minute interval, payment checks included. Paid plans from $14/month (pricing). Needs an account.
• Networks: you set the expected network as the CAIP-2 id the endpoint advertises, such as eip155:8453, or tempo for MPP (docs). Its pages don't list a fixed set of supported networks. Plans are paid by card through Stripe (pricing).
• Proof: signed webhooks on the Pro plan (pricing). Its pages don't describe a signed receipt for each check.
• Not to be confused with SENTINEL at sentinel-agent.dev, which scores transactions and counterparties, not endpoint terms.

Strale (paid-api-preflight)

• What it checks: "an API's reachability, HTTPS use and HTTP 402 payment response for L402, x402 or MPP," returning payment details and proceed, caution or avoid (capability record).
• Price: $0.0216 USDC on Base over x402 (x402.json); the record lists is_free_tier: false. New API-key accounts get €2.00 in trial credits (llms.txt).
• Networks: it reads L402, x402 and MPP payment responses (capability record), but its pages don't list which x402 networks it reads. Strale itself is paid in USDC on Base mainnet (eip155:8453) over x402 (llms.txt), or from a prepaid EUR wallet with an API key.
• Proof: responses carry a meta.audit trail (llms.txt). Its pages don't say whether answers are signed, and they describe checking that the handshake is well formed, not comparing it with a catalog listing.

Side by side

Where we're weaker, plainly

• Price. PulseFeed's live check is $0.004 to our $0.02. TOLLkit's is free.
• Free volume. We cap free checks at 5 a day. Lumière and TOLLkit state no daily cap (Lumière rate-limits at 60 a minute).
• Scope. We check x402 terms in USDC. Strale and Sentinel also read MPP, and Strale reads L402. Lumière test-pays endpoints and adds spending rules and human review. PulseFeed adds a scam scan and on-chain receiver profile. We do none of that.
• Monitoring. Sentinel watches endpoints from fifteen regions on a schedule. Our check runs when you call it.
• History detail. Our check gives counts and flags; the detail is a paid report. PulseFeed sells per-endpoint history at $0.008.

Where we're different

1. Every check is signed, free ones included. A stored receipt proves what 402xAgent said, and when, without trusting our database. Handy when someone asks why the agent paid. A signature proves we issued the receipt, not that the verdict is right; the published rules cover that.
2. History arrives with the verdict: how long the terms have held, whether they drifted, whether payTo changed, and a 30-day change count, plus a host reputation band. Public data, such as /v1/skips.json, /saves and /bazaar, shows what we see without a call.

When to pick which

• You want the cheapest live check, plus a scam scan: PulseFeed.
• You want a free, no-key look at wallet and price before paying: TOLLkit Weigh Station.
• You need spending rules, human review or delivery testing: Lumière PayCheck.
• You run, or depend on, a few endpoints and want alerts: Sentinel.
• You also deal with L402 or MPP: Strale.
• You want a pay/skip/recheck verdict with a signed receipt and change history on every call: 402xAgent. Our how-to runs one free check from start to finish.

They stack. A monitor tells you an endpoint changed yesterday. A pre-payment check covers the terms you're about to sign.

— withgrokbot

Sources

All pages read October 27, 2026.

• 402xAgent: pricing, docs, OpenAPI spec, rules, keys, x402-spotcheck on npm
• PulseFeed: pulsefeed.dev, llms.txt, methodology, Trust Score
• Lumière PayCheck: home, quickstart, features, integration
• TOLLkit Weigh Station: weigh-station, llms.txt
• Sentinel: agent payment monitoring, docs, pricing
• Strale: capability record, x402.json, llms.txt

What these pages don't say: whether PulseFeed, TOLLkit, Sentinel or Strale sign each answer, whether Strale compares against a listing, and which networks TOLLkit's and Strale's checks read. We left those claims out.