Getting Started
MPP - Machine Payments Protocol
What is MPP?
The Machine Payments Protocol (MPP) is an IETF-based HTTP authentication scheme that enables AI agents and automated systems to pay for API access on a per-request basis. Instead of requiring API keys and subscriptions, MPP lets machines pay for each API call using the standard HTTP 402 Payment Required flow.
Tomba's MPP integration is available at agents.tomba.io and powered by InFlow, supporting both fiat (USD) and crypto (USDC) payments.
Why MPP?
| Traditional API Access | MPP Access |
|---|---|
| Requires account registration | No account needed |
| API key + secret authentication | Payment replaces authentication |
| Monthly subscription plans | Pay-per-request pricing |
| Usage quotas and limits | Pay for what you use |
| Manual billing management | Automated machine-to-machine payments |
How It Works
MPP follows a simple challenge-response flow:
Step-by-Step
- Request — The AI agent calls a Tomba agent endpoint (e.g.,
agents.tomba.io/domain-search) - Challenge — The proxy returns
402 Payment Requiredwith a payment challenge in theWWW-Authenticateheader - Pay — The agent's MPP buyer (via mppx CLI) creates a payment transaction with InFlow
- Retry — The agent retries the request with
Authorization: Payment <credential> - Proxy — agents.tomba.io verifies the payment, then proxies the request to
api.tomba.io - Receipt — A
Payment-Receiptheader is included in the response for proof of payment
Base URL
Code
Available Endpoints
All Tomba API tools are available as pay-per-request endpoints:
| Endpoint | Description |
|---|---|
GET /domain-search | Search emails by domain |
GET /email-finder | Find email by name + domain |
GET /email-verifier | Verify an email address |
GET /email-count | Count emails for a domain |
GET /email-sources | Find email sources |
GET /email-format | Get email format for a domain |
GET /author-finder | Find author email from URL |
GET /enrich | Enrich an email address |
GET /linkedin | Find email from LinkedIn URL |
GET /phone-finder | Find phone by email/domain |
GET /phone-validator | Validate a phone number |
GET /similar | Find similar domains |
GET /location | Get location data |
GET /people/find | People enrichment |
GET /companies/find | Company enrichment |
GET /combined/find | Combined enrichment |
Discovery Endpoints
| Endpoint | Description |
|---|---|
GET / | Agent commerce index (JSON) |
GET /.well-known/agent-card.json | Agent card |
GET /.well-known/mpp.json | MPP config and pricing |
GET /openapi.json | OpenAPI 3.1 spec |
GET /llms.txt | LLM-friendly docs |
GET /skill.md | Skill file with mppx examples |
Supported Payment Rails
| Rail | Description |
|---|---|
tempo_mpp | MPP via InFlow / mppx CLI |
x402_base | x402 USDC on Base |
Supported Currencies
| Currency | Rail | Description |
|---|---|---|
USDC | balance | Crypto stablecoin via InFlow balance |
USDT | balance | Crypto stablecoin via InFlow balance |
USD | instrument | Fiat USD via payment instrument |
EUR | instrument | Fiat EUR via payment instrument |
Pricing
MPP pricing is based on $9.80 per 1,000 credits (1 credit = 1 API request), which works out to $0.0098 USDC per request. The exact amount is included in every 402 challenge response.
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