The full upstream README, mirrored here for reference. Install config, tool schemas, adoption signals, and an original overview live on the DefaultBench listing page.
DefaultBench is sponsored search for AI agents, MCP servers, APIs, tools, and x402 services.
Agents can search without an account. Vendors purchase sponsored placement with verified USDC payments over x402. Paid rank is not an endorsement of quality, safety, trustworthiness, or performance.
The deployed service at defaultbench.com is the source of truth. This repository is a public discovery and integration surface; it does not contain the private application implementation.
DefaultBench is a machine-first marketplace for discovering software agents and services by keyword. Search results expose sponsored listings and their cumulative verified payment. Within a keyword, listings rank by cumulative verified USDC payment, with deterministic tie-breaking.
No account, email, OAuth flow, or browser checkout is required to search. The service publishes REST, OpenAPI, MCP, A2A Agent Card, llms.txt, API catalog, and x402 discovery surfaces.
Use DefaultBench when you need candidates for a capability such as research, code-review, or pdf-parser:
Start with the live llms.txt or the more detailed llms-full.txt.
Search is zero-auth and machine-readable. Results include matching keyword markets, sponsored listings, each listing's rank, and cursor pagination. See examples/search.sh and examples/search.ts.
| Client | Live entry point | Use it for |
|---|---|---|
| REST client | /api/v1/search | Search, listing inspection, keyword rankings, quotes, activity, and statistics |
| OpenAPI client | /openapi.json | The authoritative structured HTTP contract |
| MCP host | /mcp | Read-only discovery tools over remote Streamable HTTP |
| A2A client | /.well-known/agent-card.json | Agent Card discovery for the HTTP+JSON A2A interface |
| Coding agent or crawler | /llms.txt | Concise machine-oriented service index |
| Coding agent needing details | /llms-full.txt | Complete protocol, payment, and retry guidance |
| API catalog client | /.well-known/api-catalog | RFC 9727 linkset discovery |
See docs/discovery.md for the full map.
DefaultBench exposes a remote Streamable HTTP MCP server at:
It implements MCP 2026-07-28 and exposes four read-only tools:
search_agentsinspect_keywordquote_rankget_listingPaid writes are deliberately not MCP tools; bidding remains an explicit x402 REST flow. The registry manifest is server.json.
Use the live OpenAPI 3.1.1 document to generate clients or inspect schemas and error codes. This repository does not fork that contract because a copied specification would become stale.
The paid endpoint is:
An unsigned request returns HTTP 402 and a PAYMENT-REQUIRED x402 v2 challenge. The client validates the exact network, USDC asset, recipient, amount, resource URL, and timeout before authorizing anything. A paid retry uses PAYMENT-SIGNATURE plus an Idempotency-Key exactly equal to the x402 payment-identifier extension ID.
Production uses Base mainnet and native USDC. Never sign or pay merely because a server returned 402; enforce an independent spending policy and explicit user authorization. See examples/x402-bid.ts, which can inspect the flow but cannot sign or settle a payment.
Within one canonical keyword, active listings are ordered by:
Search relevance selects matching keyword markets; it does not convert paid rank into a quality score. Quotes are snapshots, not reservations. The settlement-time transaction is authoritative.
Read the exact behavior in docs/ranking.md.
For framework authors, see docs/integrating-defaultbench.md.
The examples default to read-only behavior. The x402 example contains no signer, accepts no private key, and never sends PAYMENT-SIGNATURE.
This repository is licensed under the MIT License.