> For the complete documentation index, see [llms.txt](https://docs.rozo.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.rozo.ai/products/agentic-payments-mpprouter.md). # Agentic Payments (MPP Router) Agentic payments let AI agents spend Stellar USDC to call paid HTTP APIs — no API keys, no subscriptions, no credit card on file. The agent makes a request, the server returns `402 Payment Required` with a Stellar payment challenge, the agent signs with its wallet, retries the request, and receives the response. ROZO's agentic payment stack runs on **Stellar mainnet** via [MPP Router](https://www.mpprouter.dev) — a Stellar-native 402 proxy that accepts Stellar USDC and forwards the request to upstream merchants. The router fronts **90+ upstream services** across **670 endpoints**, including OpenAI, Anthropic, DeepSeek, Mistral, Gemini, Grok, Groq, OpenRouter, Perplexity, Exa, Firecrawl, Tavily, Brave, Parallel.ai, Replicate, fal, Stability AI, Deepgram, DeepL, Alchemy, Dune, Nansen, CoinGecko, QuickNode, Mapbox, Google Maps and WolframAlpha. One Stellar USDC balance pays for all of them — no per-service API key, no subscription, no card on file. ## Why Stellar for agentic payments * **Sub-cent fees.** Each 402-gated call settles for fractions of a cent, making microtransactions practical. * **Fast finality.** Stellar closes ledgers every \~5 seconds, so the 402 → pay → retry loop completes in one round trip. * **Sponsored transactions.** The agent's wallet does not need XLM for fees — MPP Router sponsors the fee payer. * **One stablecoin balance, many APIs.** You hold USDC on Stellar once and spend it across 90+ upstream services — no need to fund Base, Tron, or Solana. ## The flow ``` Agent Server (402-gated) │ │ │ ───── 1. POST /endpoint ────────────▶ │ │ │ │ ◀──── 402 Payment Required ───────── │ │ WWW-Authenticate: Payment │ │ request="" │ │ │ │ sign challenge with │ │ Stellar wallet (sponsored mode) │ │ │ │ ───── 2. POST /endpoint ────────────▶ │ │ Authorization: Payment │ │ │ │ ◀──── 200 OK + Payment-Receipt ──── │ ``` 1. First request: plain HTTP POST to the service URL. 2. Server responds `402 Payment Required` with a Stellar charge challenge (either MPP's `WWW-Authenticate: Payment` header or the x402 `Payment-Required` header). 3. Agent signs the challenge with its Stellar key. The inner transaction is a sponsored SAC transfer — the agent's account is `ALL_ZEROS` and only the auth entries are signed, so the server can fee-bump and broadcast. 4. Agent retries the request with the signed credential in the `Authorization` header. 5. Server validates the credential, broadcasts the signed transaction, and returns the upstream response plus a `Payment-Receipt` header. ## Protocols supported MPP Router emits a single `402` response that carries **both** dialects. The inner signed XDR is identical — a single signer produces both envelopes. | Aspect | x402 | MPP | | -------------- | -------------------------------- | -------------------------------------------- | | Outer envelope | `X-Payment` header (base64 JSON) | `Authorization: Payment ` header | | Field names | `payTo`, `asset`, `amount` | `recipient`, `currency`, `amount` | | Sponsored flag | `extra.areFeesSponsored` | `feePayer: true` | | Inner XDR | Same sponsored SAC transfer | Same sponsored SAC transfer | The MPP and x402 `payTo` addresses in a single challenge are **different** and HMAC-bound — pay the address that matches the dialect you chose. Never mix. ## Discovering services The service catalog is live at `https://apiserver.mpprouter.dev/v1/services/catalog`. Never hardcode service paths — the catalog is the source of truth, and it carries its own `generated_at` timestamp plus a `summary` block with the current counts. As of 2026-08-11 the catalog reports **670 endpoints from 94 upstream providers**, of which **444 are payable** and **15 are paid-verified** — meaning a real paid call was made through them and the settling Stellar transaction hash is published. Treat unverified entries as available but untested. Representative services: | id | price | upstream | | ------------------ | ---------------- | ---------------------------------- | | `openai_*` | dynamic | OpenAI models | | `anthropic_*` | dynamic | Anthropic models | | `openrouter_chat` | dynamic | OpenRouter LLM proxy | | `perplexity_*` | dynamic | Perplexity search-grounded answers | | `parallel_search` | $0.01 / request | Parallel.ai web search | | `exa_search` | $0.005 / request | Exa neural search | | `firecrawl_scrape` | $0.002 / request | Firecrawl HTML → markdown | | `tavily_*` | dynamic | Tavily agent search | Prices and availability change; the table above is illustrative and the catalog is authoritative. ## Getting started The fastest path for Claude Code or similar AI agents is the [`stellar-agent-wallet`](https://github.com/mpprouter/stellar-agent-wallet-skill) plugin. Seven skills ship in it — `onboard`, `check-balance`, `discover`, `pay-per-call`, `send-payment`, `send-raw` and `bridge` — of which two drive the pay-per-call loop: * `discover` — fetch and filter the MPP Router service catalog * `pay-per-call` — execute the full 402 → sign → retry loop, handling both MPP and x402 dialects Install the plugin, then: ```bash # Find a service ./node_modules/.bin/tsx skills/discover/run.ts --query "web search" # Call it — the skill pays automatically ./node_modules/.bin/tsx skills/pay-per-call/run.ts \ "https://apiserver.mpprouter.dev/v1/services/parallel/search" \ --body '{"query": "Summarize https://stripe.com/docs"}' \ --method POST ``` For custom integrations, use the `@stellar/mpp` SDK on npm with `@stellar/stellar-sdk ^14.6.1` and `mppx ^0.4.11` as peer dependencies. ## Safety notes * **Credentials are single-use.** The HMAC binding to amount, currency, and recipient is the router's defense against replay. If the retry fails, start fresh with a new 402 challenge — do not re-send the same credential. * **Confirm above a threshold.** For mainnet calls above \~$1.00, prompt the user before signing. The `pay-per-call` skill enforces this by default (`--max-auto ` to override). * **Validate the challenge amount.** If you know the advertised price from the catalog, verify the 402 challenge amount matches before signing. * **Mainnet only.** MPP Router does not run on Stellar testnet. ## Relationship to ROZO MPP Router is the agentic payments rail that lets ROZO's Stellar-native wallets pay for off-chain services with the same USDC balance used for cross-chain intents. An agent holding USDC on Stellar can: 1. Bridge from another chain to Stellar USDC via a ROZO intent. 2. Call any MPP Router service and pay per request. 3. Send the result to an intent for further action (e.g. swap, settle, bridge back). ## Further reading * MPP Router: * Live service catalog: * Stellar Soroban smart-account payments: [Stellar Smart Account Payments](/integration/api-doc/bridge-api/stellar-contract-payments.md) * `stellar-agent-wallet` plugin skills: `onboard`, `check-balance`, `discover`, `pay-per-call`, `send-payment`, `send-raw`, `bridge` *** *Last updated: 2026-08-11. Service counts verified against the live catalog on that date.*