"A guide to backtesting strategies and tools" matching MCP connectors:

Conformance checker for MCP servers. Free, no key, verdicts recomputable and re-measured daily.

Detect breaking changes, generate changelogs, diff, and validate OpenAPI specs.

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

Discover, pay for, execute, and publish APIs through Apiosk.

Point Gecko at an OpenAPI spec; get first-call-correct, auth-hidden agent tools.

Point Claude Code, Qwen Code, Cursor, or any MCP client at https://docs.jmeter.ai/api/mcp and your agent answers JMeter questions grounded in this documentation, with a source link for every answer. Free, no API key, no signup.

Keyless webhook endpoints: capture, wait, replay, forward, and generate types from real traffic.

Regex matching, email/URL format validation, and JSON Schema validation.

Search the JoJ API marketplace, read endpoint docs, and call any API with one key via one gateway.

Validate OpenRTB bid requests and responses against IAB specs. ARTF, Rust core.

Deploy production REST APIs from JSON schemas in seconds. Manage projects, schemas, and deployments.

MCP tool observatory: do registry servers answer, and are their answers true? No key.

Your DRF API as MCP tools — 1,800 endpoints become 16 dispatchers, permissioned by Django.

Apideck Unified API MCP — 330 tools across 200+ SaaS connectors (accounting, CRM, HRIS, ATS).

Deterministic JSON checks with signed evidence and x402-paid execution

Anonymous webhook capture, inspection, waiting, and response configuration for AI agents.

Create hosted mock REST APIs as tools: seed fake data, import specs, query, write, snapshot. Free.

Instant no-signup webhook & HTTP-request inspector for testing webhooks and agent tool-callbacks.

Debug webhooks from your AI agent: inspect and replay captured webhooks on localhost.

Unified gateway exposing 150+ tools across all NexGenData MCP servers via one endpoint.