HUMAN-LED
A familiar API journey
- 1Find a product
- 2Create an account
- 3Choose a plan
- 4Obtain credentials
- 5Configure billing
WHAT IS MAHSHAR?
APIs become economic building blocks for agents.
Mahshar is a marketplace and payment-aware access layer for APIs. Providers can offer an existing endpoint at a per-call USDC price, while builders and autonomous agents can discover it, pay for a request, and receive the result through one coherent interface.
Mahshar connects the transaction. It does not own or replace the provider’s backend.
THE MISSING LAYER
APIs were built for integration. Agents add a new kind of customer.
Conventional API sales often begin with a person evaluating a product and setting up an ongoing commercial relationship. That remains useful. An autonomous client, however, also needs a path it can understand and act on during execution.
PROGRAMMATIC
An agent-ready journey
- 1Discover a service
- 2Inspect terms
- 3Read the price
- 4Authorize payment
- 5Call the interface
Mahshar adds a discovery and pay-per-call surface alongside existing subscriptions, direct contracts, and provider-owned customer relationships.
HOW MAHSHAR WORKS
From discovery to a purchased result.
The public catalog and the paid execution path have distinct jobs. Public pages explain what is available; the Buyer application and agent interface handle actual paid use.
- 01
Discover
Active APIs appear in Mahshar’s public Marketplace and machine-readable agent interface.
- 02
Inspect
Builders and agents can review public metadata, the request contract, and the listed USDC price.
- 03
Pay
A request to a paid resource returns an x402 payment requirement that the buyer can authorize in USDC.
- 04
Execute
After payment validation, Mahshar’s proxy calls the configured provider endpoint under its listing contract.
- 05
Receive
The result returns through Mahshar’s purchase-scoped response and access flow.
X402 WITHOUT THE JARGON
Payment becomes part of the request conversation.
The web has long reserved the status 402 Payment Required. x402 is an open standard that uses that HTTP response to communicate a machine-readable payment requirement.
A client requests a paid resource, learns what payment is required, authorizes it, and retries the request with that payment attached. x402 defines the negotiation; it is not a Mahshar-only protocol, and an API does not support it automatically just because it is online.
1Request↓
2402 Payment Required↓
3USDC authorization↓
4Paid request↓
5API response
Mahshar’s current payment architecture applies this flow with USDC on Arc Mainnet.
WHY USDC?
A programmable unit for per-call prices.
USDC gives Mahshar a digital-dollar unit of account that software can work with directly. A listing can express a clear price for one call, including small pay-per-use amounts, without turning that single request into a subscription.
WHY ARC?
The network behind Mahshar’s production payment contract.
Arc is an open Layer-1 network purpose-built for programmable money in Circle’s ecosystem. Mahshar’s implemented production x402 architecture targets Arc Mainnet; that is an implementation choice, not a claim that Mahshar operates or represents Arc.
BUILT FOR TWO SIDES
One marketplace. Two different jobs to be done.
Providers need distribution and controlled access. Builders and agents need a service they can find, understand, and call.
FOR API PROVIDERS
Extend an existing API into a pay-per-call channel.
- List an existing endpoint through Mahshar’s provider flow.
- Set the implemented USDC price per call.
- Keep configured upstream credentials on the server where applicable.
- Track paid calls and earnings through the current seller interfaces.
FOR BUILDERS AND AGENTS
Discover a capability when the work demands it.
- Browse active APIs and their public metadata.
- Inspect the listed method, category, and USDC price.
- Pay per call through Mahshar’s implemented x402 flow.
- Discover eligible active listings through agent discovery, then use Mahshar’s OpenAPI-described machine interface programmatically.
CLEAR BOUNDARIES
What Mahshar does — and what it does not do.
A useful marketplace should make its role legible. Mahshar coordinates discovery, payment-aware access, and marketplace accounting while the provider remains responsible for the upstream service.
Mahshar provides
- Public discovery and API metadata
- Provider-set pay-per-call pricing
- An x402 payment flow in USDC
- Payment-aware proxy execution
- Server-side credential injection where configured
- Purchase-scoped result access
- Seller call and earnings interfaces
Mahshar does not
- Include stored seller credentials in public discovery or buyer-facing listing data
- Require public visitors to connect a wallet
- Own the provider’s upstream API
- Silently rewrite the provider’s backend
- Promise an upstream endpoint’s availability or quality
OFFICIAL RESOURCES
Continue with the underlying standards.
These sources describe the broader technologies Mahshar uses. Mahshar is an independent product and is not presented as operated or endorsed by Circle.
THE API ECONOMY IS BECOMING CALLABLE