paid-rail context for autonomous agents

L402 Agent Payments, Governed Before Access

paid-rail context can let agents satisfy HTTP 402 payment challenges. SatGate decides whether the agent is authorized to spend, unlocks only scoped access, and preserves proof for every paid action.

Govern L402 access See Policy-to-Proof

The next API call may be paid by an agent

AI agents increasingly discover, evaluate, call, and combine APIs on behalf of people and companies. That creates a new customer type: software that can decide an API is worth paying for right now.

Traditional API monetization assumes a human signs up, enters a card, picks a plan, stores a key, and then integrates. Agent/API paid access needs a request-native flow: ask for resource, receive price, pay, unlock scoped access, continue task.

L402 gives that flow an internet-native shape. SatGate treats it as paid-rail context governed by request-path policy and proof.

Good fits for L402 agent payments

Premium search, research, or enrichment endpoints.
Datasets agents query occasionally but value highly.
AI tools sold per use instead of by seat.
MCP tools exposed to external agent ecosystems.
APIs where authorization and payment should happen together.

How L402 agent payments work with SatGate

SatGate sits in the request path. The API stays protected while the agent receives a machine-readable price and payment challenge.

Agent requests a resource

An autonomous agent calls a protected API, model, dataset, tool, or premium endpoint.

SatGate returns a 402 challenge

Instead of a subscription flow or sales gate, SatGate issues an L402 payment challenge tied to the request.

Agent pays with Lightning

The agent or wallet client pays the invoice through a wallet such as SaturnZap or another L402-capable client.

Proof unlocks access

SatGate verifies payment and releases a scoped credential or forwards the approved request.

Usage is attributed

Every paid request is tied to agent identity, route, price, policy, and settlement evidence.

Proof becomes request-native

Each paid request can carry identity, policy, price, payment proof, and access decision.

402 is a surface, not one rail

L402, shared payment tokens, and agent wallets are different layers

HTTP 402 can carry different payment challenges. Some flows use card credentials or shared payment tokens. paid-rail context is one paid rail for request-native API access. Other paid rails — x402, AgentCore Payments, and Pay.sh — also use HTTP 402 as their surface but settle differently.

The important control-plane question is broader than payment: whether the agent has authority, budget, scope, and policy approval before paid access is unlocked.

Explore the payment-control stack

HTTP 402 for AI agents Agent payment controls Stripe Link for Agents vs SatGate

Governed L402 payment requirements

Machine-readable price

Agents need a price and payment challenge in the protocol flow, not a human checkout page or sales form.

Payment before access

SatGate verifies paid-rail context payment proof before forwarding the protected API request upstream.

Scoped unlocks

Payment should unlock the requested route, tool, dataset, or capability — not a broad reusable API key.

Evidence Pack receipts

Every paid request should record agent identity, route, price, payment proof, policy decision, and Evidence Pack receipt.

A governed L402 request flow

# Saturnzap CLI; any L402-capable client can present proof
sz fetch https://api.example.com/premium-research --max-sats 25

# SatGate replies with an L402 challenge
HTTP/1.1 402 Payment Required
WWW-Authenticate: L402 invoice=lnbc..., macaroon=...

# Agent pays, presents proof, and receives the resource
HTTP/1.1 200 OK
{ "answer": "paid premium result" }

In this pattern, the merchant runs SatGate. The agent or wallet client presents payment proof. Payment, authorization, receipt capture, and audit happen before upstream access.

OBSERVE

See agent demand

Understand which agents and routes create monetizable demand before forcing a pricing model.

CONTROL

Protect access

Limit which agents, routes, prices, budgets, and proofs are accepted before unlocking protected resources.

PROVE

Preserve the receipt

Use L402 payment proof as one input to a Policy-to-Proof receipt that records authority, rail, price, and decision.

FAQ

L402 agent payment questions

What are L402 agent payments?

L402 agent payments let an API return an HTTP 402 payment challenge that an autonomous agent can satisfy with a Lightning payment before receiving access.

Why use L402 for agent/API paid access?

Agent/API paid access needs programmatic, low-friction payment. L402 combines HTTP 402, Lightning invoices, and access credentials so agents can pay for APIs without manual checkout.

Is L402 enough to govern paid agent access?

No. L402 is a payment/access rail. SatGate Policy-to-Proof governs authority, scope, budget, revocation, and Evidence Pack evidence.

What APIs are good candidates for agent/API paid access?

Premium search, data enrichment, research APIs, MCP tools, datasets, model endpoints, and agent-native services are good L402 candidates when value is tied to each request.

How is L402 different from a normal API subscription?

A normal API subscription requires a human signup, plan, billing account, and long-lived key. L402 lets an agent receive a machine-readable HTTP 402 challenge, pay a Lightning invoice, and unlock scoped access for the specific request.

Can paid-rail context include budget and access policy?

Yes. SatGate can combine L402 payment proof with request-path policy for identity, route, tool, quota, expiry, revocation, and audit so paid access is still governed.

Govern L402-paid access with Policy-to-Proof

L402 can prove payment. SatGate proves the action was authorized: who acted, what policy applied, which rail was used, what was paid, and why access was allowed or denied.

Govern paid agent actions View Policy-to-Proof