"Free tools or resources that do not require an API" matching MCP servers:

A comprehensive suite of HTTP and API testing tools that enables AI agents to perform requests, check endpoint health, and decode JWTs. It also provides utilities for URL parsing and detailed security analysis of HTTP response headers.

Scans code for exposed secrets, API keys, tokens, and credentials across 69 patterns covering cloud services, AI platforms, payment providers, authentication services, and databases.

An MCP server that exposes 43 domain tools behind 4 meta-tools, applying guardrails such as budgets, rate limits, schema validation, human-in-the-loop confirmation for mutations, PII redaction, and an append-only audit log while reducing context window usage.

Post-quantum readiness for AI coding agents: scans code for quantum-vulnerable cryptography (RSA/ECDH/ECDSA/DH) and returns NIST ML-KEM/ML-DSA/SLH-DSA (and hybrid) migration guidance, with fix verification and dependency checks. Content-based, advisory tools only; runs local (npx @quantakrypto/mcp) or as a hosted OAuth endpoint.

Enables AI agents to pay per call for live package-safety and GitHub merge-readiness trust signals via the x402 protocol.

Community MCP server for the Cymulate security validation platform. It exposes the full Cymulate REST API (337 endpoints) as 106 semantic tools for BAS, exposure validation, attack surface management, and platform administration.

Wraps the Remnawave API to provide per-operation MCP tools with mutation safety and data redaction, enabling secure interaction with Remnawave panel.

Enables MCP clients to use paid tools for secret scanning, agent-config auditing, and OG image rendering, with payments handled over the x402 protocol on Base.

Signed, offline-verifiable authorization for API-contract changes. Before a contract change (OpenAPI, GraphQL, Protobuf, AsyncAPI, MCP manifests) merges or deploys, the agent calls preflight_change_set; the decision is deterministic, signed, and verifiable without calling CodeRifts. Three tools: preflight_change_set, verify_receipt, get_decision_details. Only a granted change can proceed.

Presents a plausible, tool-rich workspace surface — file reading, credential listing, command execution, database queries, and configuration retrieval — that returns only synthetic results while logging every connection, tool call, and argument received. It enables researchers to measure what MCP clients and agents actually do when handed dangerous-sounding tools, including whether they follow injected instructions or complete a retrieve-then-use credential chain.

Turns an OpenAPI specification into a broker-published slot of curated, LLM-ready tools that a human operator reviews, tests, and approves before anything goes live. The resulting tools are declarative and run under the broker's authorization, audit, execution limits, and secret handling.

Enables AI agents to perform common utility tasks through a streamable HTTP MCP endpoint, including JSON inspection, regex testing, cron parsing, hashing, base64 encoding/decoding, URL analysis, color conversion, text diffing, CSV parsing, JWT decode/verification, Markdown-to-HTML rendering, and UUID/token generation without API keys.

Provides 9 utility APIs for AI agents covering DNS, email, IP, QR, WHOIS, URL health, headers, text extraction, and tech detection, with x402 micropayments on Base.

Dependency health checker for AI agent skills. Analyzes external endpoints for uptime, SSL validity, domain reputation, ownership changes, and abuse scores. Returns a 0-100 trust score per endpoint.

MCP server for inspecting email domains and addresses, providing objective domain-level email infrastructure answers such as MX, SPF, DMARC, MTA-STS, and disposable-domain evidence.

Enables AI assistants to manage Namecheap domains, DNS, contacts, registrar locks, and view SSL certificates and pricing through safe read and configuration tools.

Enables cryptographic operations including hashing, encoding/decoding, ID generation, password tools, and JWT inspection via MCP.

Enables querying MITRE ATT&CK and D3FEND data efficiently, providing techniques, detections, mitigations, actors, and countermeasures with token-aware summaries and paginated graph traversal.

Enables testing API authentication and authorization by probing endpoints with and without Authorization headers, suggesting auth test matrices for roles, and showing current test configuration.

Fork of @cyanheads toolkit MCP server. Added encoding functions, removed system network functions.