"Understanding OAuth 2.0 Protocol" matching MCP connectors:
GET /v1/connectors – MCP directory API referenceMatching Connector Tools:
Agent Observatory: checks A2A, MCP and OpenAPI declarations and logs published changes.
Free platform to test MCP clients without installing anything. Create mock tools with dynamic templates, configurable delays, conditions (if/then), and response sequences. Supports JSON-RPC 2.0 over Streamable HTTP. Built-in text_echo and json_echo tools. Rate-limited tiers: anonymous (5 calls/min, 1 mock tool), registered (10 calls/min, 4 mock tools), premium (60 calls/min, unlimited). Zero setup — no install, no registration required. More info: https://www.testmcp.dev
Ephemeral mailboxes and a mock OAuth IdP for testing email and auth flows — 39 API-driven tools covering mailboxes, mails, attachments, domains, teams, and mock identities.
{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"whoami","arguments":{}}} free no key
Read-only ArcadeOps discovery for developer docs, OAuth, OpenAPI and synthetic sandbox.
WSDL 2.0 interface count, markup discarded
Authentication-Info nextnonce shape, value discarded
Remote MCP for 1,500+ APIs. Vault-managed credentials; OAuth or API key. Search, load, and execute.
- NahookOAuthcom.nahook.mcp
Manage your Nahook webhooks from your AI client — inspect deliveries, retry failures, and manage endpoints. Connects over OAuth, no API keys
Check public MCP reachability, protocol handshake, auth and tool schemas before connecting.
- PNTROAuthdev.pntr.api
Free *.pntr.dev dev subdomains — register subdomains, manage DNS and wildcard records, receive email on disposable inboxes, and capture HTTP requests for webhook debugging. OAuth sign-in; free tier.
Public webhook inboxes for agents. Receive OAuth redirects, payment callbacks and CI notifications.
The Grafbase MCP server sits in front of a GraphQL API and exposes an MCP protocol-compliant interface that allows AI agents and LLMs to explore and query GraphQL APIs using natural language. It provides tools to search schemas, introspect types and fields, and execute GraphQL queries while minimizing context bloat by returning only relevant schema subsets, with built-in support for authentication, authorization, and configurable access control.
20+ pay-per-use APIs: image gen, crypto data, email verify, SSL check, web scraping, and more.
