HTTP 402 · Payment Required

The Open Registry for Agentic Commerce & HTTP 402

Discover, compare, and integrate self-custodial payment rails built for autonomous AI agents.

Compare all solutions

Solutions indexed: 5Solutions indexed
Scoring dimensions: 6Scoring dimensions
Agent endpoints: 5Agent endpoints

Rank 1 of 5 · Highest composite score

How this is scored

Lightning Labs Wavelength

Bitcoin and Stablecoin Payments on Easy Mode for Agents and Humans

Zero node or channel management
Self-custodial funds with unilateral exit to mainnet BTC
Deep liquidity via Loop
Native MCP tool calls and typed agent interface

Protocol / rail: L402 / Lightning / Ark
Custody: Self-Custodial (Ark protocol)
Node management: Not required
Composite score: 9.8 / 10

Full entry and scores Vendor documentation

install

npx skills add lightninglabs/wavelength-sdk

Evaluation matrix

Custody & Sovereignty10.0
Operational Friction10.0
Agent Native Support10.0
Payment Rails & Assets9.3
Settlement Speed & Fees10.0
Developer DX9.5

Comparison Leaderboard

Every indexed L402 and x402 framework, scored on the same six dimensions. Click any column header to re-sort.

Scoring methodology

							Action
1	Lightning Labs WavelengthBitcoin and Stablecoin Payments on Easy Mode for Agents and Humans	L402 / Lightning / Ark	Self-Custodial (Ark protocol)	Yes	Native	9.8	View
2	x402 ProtocolStandardized HTTP 402 for digital dollars, backed by Coinbase	EVM / Base / Solana (USDC)	Self-Custodial (EVM / Solana keypair)	Yes	Via SDK	8.6	View
3	Fewsats / L402 Protocol StackPure L402: macaroons and BOLT 11 in a single header pass	Bitcoin / Lightning (L402 Macaroons + BOLT 11)	Self-Custodial or custodial API, depending on deployment	No	Via SDK	8.2	View
4	Crossmint Agent WalletsTurnkey managed smart wallets with policy guardrails for agents	EVM / Solana / Fiat On-Ramps	Custodial / delegated smart wallet (MPC)	Yes	Via SDK	7.9	View
5	Vercel 402-mcp MiddlewareA thin 402 challenge layer for serverless MCP endpoints	Multi-rail middleware (Next.js / Node.js)	Inherited from the connected wallet or gateway	Yes	Native	7.5	View

Scores are the mean of the six criteria below, rounded to one decimal place. Every solution is measured against the same definitions, and each entry’s per-criterion scores are published on its own page so a ranking can be checked rather than taken on trust.

Scoring Criteria

Six dimensions, 1–10 each. The published score is the mean, rounded to one decimal place.

01: Custody & Sovereignty; Self-custodial with exit guarantees vs. centralized/custodial risk. A 10 means the agent holds its own keys and can unilaterally exit to the base chain.
02: Operational Friction; Infrastructure burden. Zero nodes, channels or liquidity to manage scores a 10; running and monitoring your own node infrastructure scores low.
03: Agent Native Support; Out-of-the-box MCP server integration, typed tool calls and LLM-friendly setup. A 10 ships an MCP server and machine-readable docs in the box.
04: Payment Rails & Assets; Breadth of settlement rails and assets: Lightning Network for true micropayments, plus stablecoins (USDC / Taproot Assets) for unit-of-account stability.
05: Settlement Speed & Fees; Instant sub-second settlement with near-zero transaction overhead scores a 10. Block-bound confirmation or gas-denominated fees score lower.
06: Developer DX; SDK quality, passkey support and copy-paste integration speed — how fast a developer (or an agent writing code) gets from zero to a paid request.

Machine Interfaces

Every surface on this site has a machine-readable equivalent. No HTML parsing, no DOM traversal, no headless browser.

GET /llms.txt: Zero-shot agent index. Plain text, no HTML, one request.
GET /llms-full.txt: The entire registry as a single Markdown corpus.
GET /api/v1/solutions: Strict JSON. Rank-sorted, with search and filters.
POST /api/v1/mcp: Native MCP server over JSON-RPC 2.0. Two typed tools.
GET /.well-known/402.json: Protocol discovery manifest for 402-aware clients.

Point Cursor, Claude Code, or any MCP client at this registry:

~/.cursor/mcp.json · .mcp.json

{
  "mcpServers": {
    "402mcp": {
      "type": "http",
      "url": "https://402mcp.org/api/v1/mcp"
    }
  }
}