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I measured every x402 wallet that claims Arbitrum: $11.28 in 30 days

#api #showdev #crypto #web3

Two days ago I published the full x402 directory census: 680 services, and a payment count per rail. Three rails came back with numbers: Solana, Base, Polygon. The fourth — Arbitrum — came back as 40 declared, 0 measured.

The working assumption was a blind spot: the directory measures settlements through facilitator indices, so maybe Arbitrum was just invisible to it. This time I did the same thing I did for Solana: I crawled the live discovery document of every one of the 40 Arbitrum-declaring services I could reach, extracted every payment address they actually publish, and read the chain for 30 days.

The wallets moved almost nothing.

The method

  1. Fresh pull of the directory on 2026-09-11: 685 services (up from 680 two days ago). 40 declare eip155:42161 (Arbitrum One) in their directory listing.
  2. Live GET /.well-known/x402 for all 40: 28 reachable (the other 12 are offline or degraded in the directory too).
  3. Parsed every payment address in the 28 readable docs — across all the doc shapes I've seen (v1 routes, v2 resources with accepts, top-level payTo, per-chain payToByNetwork tables, facilitator-mode envelopes).
  4. 6 distinct EVM payment addresses are published across the 28 readable docs.
  5. 30-day USDC inflow per address on Arbitrum One: the native Circle USDC contract (0xaf88…5831, "USD Coin", the one the docs themselves name), read as Transfer logs on public RPCs, block-timestamp-anchored window 2026-08-12 → 2026-09-11.
  6. Same six addresses, same window, on Base as a control (USDC 0x8335…02913, via the Blockscout API).

One catch worth flagging: my first pass used a wrong USDC address (a lookalike 0xaf88…7526 that has no deployed code), which would have read as zero for everyone. The address above is the one the services' own docs declare, verified on-chain before I trusted a single number.

The cascade 

40 services declare Arbitrum in the directory
  → 28 live discovery docs reachable (12 offline)
    → 6 of the 28 still declare Arbitrum in the live doc
      (3 of those 6 publish no wallet at all)
    → 6 distinct EVM payment addresses published across the 28 readable docs
      → 1 of the 6 received any USDC on Arbitrum in 30 days:
        187 tx / $11.28 — all from agent402-tools, whose own live doc
        no longer declares Arbitrum
        (the 3 wallets the live docs DO map to Arbitrum: $0)
        (the same 6 received $1,325.14 on Base in the same 30 days)
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$11.28 is the entire 30-day Arbitrum inflow to every wallet these services publish. For scale, the same six wallets received 5,992 USDC inflow transactions worth $1,325.14 on Base over the same window — scvd.store's wallet took 185 tx / $1,212.41 from 16 distinct senders, the agent402-tools wallet took 5,786 tx / $112.56 from 128, and the rest (21 tx / $0.17) went to one more.

The six live docs, spelled out

  • 3 services (agentbit, edge-agents-ai, onchainpulse) declare Arbitrum but publish no wallet at all in the doc — agentbit's payment mode is literally facilitator, so the receiving wallet lives with the payment processor, not in the file. The other two omit the wallet the same way; there's no on-chain address to measure.
  • 3 services publish wallets that the live doc maps to Arbitrum: saylor-innovations-watchdog-token-intelligence maps one address to every chain in a payToByNetwork table; scvd.store and x402-extract-api declare four or more EVM chains and publish one global wallet that would receive on any of them. All three, measured on Arbitrum: exactly zero.
  • The remaining 22 readable docs carry Arbitrum in the directory listing only. The live doc either names no network at all or names a different set. The directory claim is older than the doc.

The $11.28 did not come from any of those six. It came from agent402-tools — one of the docs whose live version no longer declares Arbitrum at all. 187 transactions from 4 distinct senders, all in the window. The directory still lists it as an Arbitrum claimant; its own doc quietly dropped the chain. That's the whole story of Arbitrum x402 settlement to declared wallets: one wallet that stopped declaring, and it moved eleven dollars.

Why $11.28 is the finding

The directory's "0 measured" for Arbitrum is mostly right, in the most literal sense. Unlike Solana — a real blind spot, where my declared-wallet measurement found $12.84 of activity the directory couldn't see — there's almost no hidden activity to find here. Three mechanisms, each verified:

  1. Stale declarations. Only 6 of 28 readable live docs still claim Arbitrum. The directory's network field outlives the doc — and the one wallet that did move is attached to a doc that already gave up.
  2. Facilitator-held wallets. When the processor holds the wallet, the "declared address" doesn't exist as a measurable on-chain address at all — the same no-payTo pattern I found on Solana, in facilitator clothing.
  3. The money settles elsewhere. Bitquery's August 2026 x402 audit found that 97.5% of Arbitrum's measured x402 volume runs through one bridge contract (Circle's CCTP bridge extension, CctpExtension — 34,577 distinct payers, median $749, one $10M payment) — settlement that never touches a service's declared wallet. Take that contract out and the chain moved $317M, not $2.59B.

Declaring a chain is marketing. Settling on a chain is a number. On Arbitrum, the number for declared wallets is $11.28 in 30 days.

What this means if you sell over x402

  • The rail you claim is a product decision, not a checkbox. Six of the forty claimants still have a live doc that matches the directory. If an agent's payment path routes to "eip155:42161" and your declared wallet has never received on that chain, you're advertising a route.
  • If your facilitator holds the wallet, say so in the doc. A payTo you can't publish is a wallet the directory and the auditor can't see — and right now "can't see" reads as "doesn't exist".
  • Base is still the settlement default. Every wallet with real x402 volume in this pass settled on Base ($1,325.14) — a hundred times the Arbitrum total. Per the audit, Arbitrum's measured x402 dollars are one bridge contract, not a merchant rail.

The data

Full per-address table (both chains), method, and caveats as a dated CC BY 4.0 snapshot: GET https://api.pennyforge.org/arbitrum-rail (same pattern as the Solana rail file: https://api.pennyforge.org/solana-rail).

Caveats, stated plainly: addresses are the ones currently published — a service that rotated its wallet in the last 30 days is missed, and 12 of the 40 docs were unreachable, so this is a floor. Native USDC only — bridged USDC.e or a USDT/DAI settlement would be invisible to this pass. And $11.28 is a 30-day fact, not a verdict on the chain: the rail can start tomorrow.

Pennyforge is a one-person studio selling address verification over x402. This measurement cost $0 in public RPCs and one afternoon. Raw docs, crawl scripts, and the corrected token address are kept with the data file.

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