x402 Base Pulse

Real-time payment protocol analytics for Coinbase x402 on Base

Track every x402 payment settlement on Base. This Substreams detects when facilitators call transferWithAuthorization on USDC to settle HTTP 402 payments, extracting payer, recipient, amount, and facilitator data from each settlement.

v3.2.0 — Enriches every settlement with the EIP-3009 validity window (valid_after / valid_before, decoded from the transferWithAuthorization call — a real fraud/anomaly signal) and a scheme field (exact / batch). Fixes the Permit2 proxy address: the previous 0x4020615… / 0x4020633… addresses carry no contract code on Base; the live proxy is 0x402085c2…0001. Adds forward-looking batch-settlement capture (x402BatchSettlement Settled sweeps → scheme="batch"; recipient/amount/token exact, payer approximate pending channel-level attribution in v3.3).

v3.1.0 — Adds a static facilitator allowlist (112 addresses across 29 operators) sourced from Merit Systems' x402scan facilitators package. The gate now accepts a settlement if tx.from is either on-chain-registered via FacilitatorRegistry or present in the published allowlist. In practice the on-chain registry is sparsely populated (only Meridian as of 2026-05), so without the allowlist virtually no real x402 activity would be indexed. Matches gating used by x402scan + x402-omnigraph subgraph.

v3.0.0 — Gated EIP-3009 settlements through the on-chain FacilitatorRegistry only. Facilitator names, URLs, and active status resolved from registry events. Deprecated: produces empty output in practice — use v3.1.0.

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How It Works

The x402 protocol enables internet-native payments using the HTTP 402 status code. When a client wants to access a paid resource:

1. Server responds with HTTP 402 + payment requirements
2. Client signs an EIP-3009 authorization
3. Facilitator calls transferWithAuthorization on USDC to settle payment on-chain
4. USDC emits AuthorizationUsed + Transfer events
5. This Substreams captures those events and extracts settlement data
6. Facilitator gate — settlements are kept only if tx.from is either on-chain-registered via FacilitatorRegistry or on the published static allowlist (x402scan's facilitators npm package, baked into the WASM at build time)

Modules

Module	Kind	Description
map_facilitator_registry_events	Map	Extracts FacilitatorAdded / FacilitatorRemoved events from the on-chain registry
store_facilitator_registry	Store	Maintains the set of registered facilitators with names and URLs
map_x402_settlements	Map	EIP-3009 (AuthorizationUsed+Transfer, + validity window from the call), Permit2 proxy (Settled/SettledWithPermit), and batch-settlement sweeps; gates by FacilitatorRegistry OR static allowlist
store_payer_volume	Store	Accumulates total USDC spent per payer
store_payer_count	Store	Counts payments per payer
store_recipient_volume	Store	Accumulates total USDC received per resource server
store_recipient_count	Store	Counts payments per recipient
store_facilitator_volume	Store	Accumulates total USDC volume per facilitator
store_facilitator_count	Store	Counts settlements per facilitator
store_facilitator_gas	Store	Tracks gas costs per facilitator
store_first_seen	Store	Records first-seen timestamp per payer, recipient, and facilitator
map_payer_stats	Map	Computes payer leaderboards and averages
map_recipient_stats	Map	Computes resource server revenue stats
map_facilitator_stats	Map	Computes facilitator economics with name, URL, and active status from registry
db_out	Map	Outputs DatabaseChanges for PostgreSQL sink

Contracts Indexed

Contract	Address	Events
USDC (Base)	0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913	AuthorizationUsed, Transfer (+ transferWithAuthorization call for validity window)
FacilitatorRegistry	0x67C75c4FD5BbbF5f6286A1874fe2d7dF0024Ebe8	FacilitatorAdded, FacilitatorRemoved
x402 Permit2 Proxy	0x402085c248eea27d92e8b30b2c58ed07f9e20001 (live; old …615/…633 have no code)	Settled, SettledWithPermit
x402BatchSettlement	detected by event signature, gated by token == USDC	Settled(receiver, token, sender, amount)

Quick Start

# Stream settlements
substreams run x402-base-pulse map_x402_settlements \
  -e base-mainnet.streamingfast.io:443 \
  -s 29000000 -t +1000

# GUI mode
substreams gui x402-base-pulse map_x402_settlements \
  -e base-mainnet.streamingfast.io:443 \
  -s 29000000

# Sink to PostgreSQL
substreams-sink-sql run "psql://localhost/x402" \
  x402-base-pulse-v3.2.0.spkg \
  -e base-mainnet.streamingfast.io:443

SQL Output

Tables

Table	Key	Description
settlements	tx_hash-log_index	Every settlement: payer, recipient, amount, facilitator, gas, scheme, validity window (valid_after/valid_before), nonce
payers	payer_address	Aggregated spend and payment count per payer
recipients	recipient_address	Revenue and payment count per resource server
facilitators	facilitator_address	Name, URL, active status, volume settled, settlement count, total gas spent

Views

View	Description
daily_stats	Daily protocol-wide volume, unique participants, gas
top_payers	Ranked by total USDC spent
top_recipients	Ranked by total USDC received
facilitator_economics	Name, active status, volume settled vs gas cost per facilitator
whale_payments	Payments > $100 USDC
recent_settlements	Latest 100 settlements

Build

cargo build --target wasm32-unknown-unknown --release
substreams pack substreams.yaml

References

• x402 Protocol -- Coinbase's HTTP 402 payment standard
• How It Works -- Settlement flow
• Network Support -- Supported tokens and chains
• EIP-3009 -- Transfer With Authorization
• x402 Source -- Protocol implementation
• x402-subgraph -- Companion subgraph with matching facilitator gating

Network

• Chain: Base
• Start Block: 25,000,000 (settlements), 30,011,612 (FacilitatorRegistry)
• Endpoint: base-mainnet.streamingfast.io:443