{"requirements":{"role":"pay","custody":"self"},"weights":{"custody_sovereignty":1.5,"operational_friction":1,"agent_native_support":1,"payment_rails_assets":1,"settlement_speed_fees":1,"developer_dx":1},"notes":[],"recommendations":[{"id":"lightning-labs-wavelength","name":"Lightning Labs Wavelength","rank":1,"score":9.4,"fit_score":9.46,"schemes":["L402"],"roles":["pay","charge"],"kind":"wallet","maturity":"alpha","maturity_note":"Launched in alpha on 21 July 2026. The repository warns RPC surfaces and CLI commands may change between minor versions, and gates mainnet behind an explicit --allow-mainnet flag.","why":["Lets an agent pay 402 challenges","Self-custodial","No node to run","Ships an MCP server or MCP-native tooling","Settles over Lightning — sub-second and economical below one cent","Speaks L402"],"trade_offs":["Alpha: RPC surfaces, on-disk schema and CLI commands may change across minor versions","Mainnet is gated — the repository requires an explicit --allow-mainnet flag, and launch coverage describes mainnet access as invitation-only","Bitcoin-denominated: no stablecoin settlement today"],"install":"npx skills add lightninglabs/wavelength-sdk","docs_url":"https://wavelength.lightning.engineering/","url":"https://402mcp.org/solutions/lightning-labs-wavelength"},{"id":"x402-protocol","name":"x402 Protocol","rank":2,"score":8.6,"fit_score":8.62,"schemes":["x402"],"roles":["pay","charge"],"kind":"protocol","maturity":"production","maturity_note":"Protocol v2; the @x402/* reference packages were at 2.28.0 in September 2026.","why":["Lets an agent pay 402 challenges","Self-custodial","No node to run","Stablecoin settlement gives a stable USD unit of account","Speaks x402"],"trade_offs":["Settlement is block-bound, so sub-cent payments are less natural than on Lightning","v1 and v2 use different headers (X-PAYMENT vs PAYMENT-SIGNATURE); clients must read x402Version to pick the right one","The protocol ships no MCP server itself — MCP support comes from ecosystem packages"],"install":null,"docs_url":"https://docs.x402.org/","url":"https://402mcp.org/solutions/x402-protocol"},{"id":"alby-mcp","name":"Alby MCP Server","rank":3,"score":8.3,"fit_score":8.31,"schemes":["L402"],"roles":["pay","charge"],"kind":"mcp-server","maturity":"unstated","maturity_note":null,"why":["Lets an agent pay 402 challenges","Self-custodial","No node to run","Ships an MCP server or MCP-native tooling","Settles over Lightning — sub-second and economical below one cent","Speaks L402"],"trade_offs":["L402 needs a wallet that returns the payment preimage — not every NWC wallet does","Custody follows the connected wallet; a custodial NWC wallet is custodial","Lightning bitcoin only"],"install":"npx -y @getalby/mcp","docs_url":"https://github.com/getAlby/mcp","url":"https://402mcp.org/solutions/alby-mcp"},{"id":"cloudflare-agents-x402","name":"Cloudflare Agents SDK (x402)","rank":4,"score":8.3,"fit_score":8.31,"schemes":["x402"],"roles":["pay","charge"],"kind":"sdk","maturity":"unstated","maturity_note":null,"why":["Lets an agent pay 402 challenges","Self-custodial","No node to run","Ships an MCP server or MCP-native tooling","Stablecoin settlement gives a stable USD unit of account","Speaks x402"],"trade_offs":["Documented networks are Base and Base Sepolia","Tied to Cloudflare Workers and the Agents SDK"],"install":"npm install agents","docs_url":"https://developers.cloudflare.com/agents/tools/payments/x402/charge-for-mcp-tools/","url":"https://402mcp.org/solutions/cloudflare-agents-x402"},{"id":"machine-payments-protocol","name":"Machine Payments Protocol (MPP)","rank":6,"score":8.3,"fit_score":8.23,"schemes":["MPP"],"roles":["pay","charge"],"kind":"protocol","maturity":"preview","maturity_note":"The core is draft-ryan-httpauth-payment-01 (March 2026), an individual Internet-Draft with no formal IETF standing; method and intent specs are also drafts.","why":["Lets an agent pay 402 challenges","Self-custodial","No node to run","Settles over Lightning — sub-second and economical below one cent","Stablecoin settlement gives a stable USD unit of account","Accepts cards","Speaks MPP"],"trade_offs":["An individual Internet-Draft with no formal IETF standing; method specs are still drafts","Custody, fees and settlement speed depend entirely on the method chosen","A younger ecosystem than x402"],"install":null,"docs_url":"https://paymentauth.org/","url":"https://402mcp.org/solutions/machine-payments-protocol"}],"excluded":[{"id":"coinbase-payments-mcp","name":"Coinbase Payments MCP","reasons":["Not self-custodial"]},{"id":"thirdweb-x402","name":"thirdweb x402","reasons":["Not self-custodial"]},{"id":"payai-x402-facilitator","name":"PayAI Network","reasons":["Does not pay 402 challenges"]},{"id":"crossmint-agent-wallets","name":"Crossmint Agent Wallets","reasons":["Not self-custodial"]},{"id":"stripe-machine-payments","name":"Stripe Machine Payments","reasons":["Does not pay 402 challenges","Not self-custodial"]},{"id":"lightning-labs-aperture","name":"Aperture","reasons":["Does not pay 402 challenges"]},{"id":"fewsats-l402","name":"Fewsats","reasons":["Not self-custodial"]}],"method":"Hard requirements filter the registry; the remainder are ordered by a weighted mean of the six published criteria, with weights raised for what you said matters. Published rank is shown for reference but does not order these results."}