"Free APIs and services without commercial fees" matching MCP servers:

Offers a control surface for AI agent security with four independent checks: source-code scanning, tenant isolation, LLM content verification, and deploy gating. Currently in pre-release, with no functional scanning engines yet.

Enables users to run synthetic support-agent evaluations, preserve and inspect traces, score results deterministically, inject failures, and enforce release review gates through MCP tools, resources, and prompts.

Enables AI agents to perform passive security scans on domains, checking email spoofing (DMARC/SPF/DKIM), TLS weaknesses, security headers, exposed files, and subdomain-takeover risk without needing an API key.

Enables assistants to analyze files and URLs for malware by integrating with security services like VirusTotal and ANY.RUN, returning threat reports.

A minimal, dependency-free MCP server that gives AI agents three real, read-only security-orchestration tools: cve_lookup, shodan_host_lookup, and nuclei_scan.

Enables interaction with NowSecure Platform for listing applications, retrieving remediation findings, and generating remediation PDFs via REST and GraphQL APIs.

Domain security reconnaissance for AI agents — 13 tools (DNS+DNSSEC, SSL/TLS, HTTP security headers, SPF/DKIM/DMARC email auth, port scan, ASN, RDAP/WHOIS) plus a one-shot security_scan returning a 0–100 Health Score (A–F). Free, no API key.

This server enables AI-assisted APK reverse-engineering entirely on-device, orchestrating jadx, apktool, adb, frida, and APKiD through a job/workflow engine, and exposing those agents as native MCP tools for Claude without any cloud dependency.

Automates Android app analysis using Frida via AI commands, connecting a rooted Android phone to a computer and running dynamic analysis scripts without manual command execution.

Free deterministic security scan of a public git repository (GitHub, GitLab, Codeberg, Bitbucket): vulnerable dependencies via OSV.dev, secret patterns, and config lint, returned as structured JSON. Tools: scan_repository(url), audit_pricing(). Runs locally over stdio (python3 web/mcp_stdio.py or the Dockerfile) and is also hosted at https://project-feldspar.com/mcp. MIT licence, stdlib-only. Buil

Enables sudo-free management of /etc/hosts entries for Hack The Box and lab work, with a zero-dependency MCP server for AI coding agents.

Vulnerability intelligence for AI agents that enables CVE lookup, package vulnerability checks, and dependency auditing without API keys.

Enables interactive Ghidra reverse-engineering inside an AI client by rendering live decompiler, function browser, and call graph views. Users can click symbols to rename them and follow calls to navigate, all without leaving the conversation.

Enables AI coding agents to run sub-millisecond, fully offline CVE lookups and audit dependency manifests such as requirements.txt and package.json against known vulnerable version ranges. It returns CVSS severity details and calculates the minimal safe upgrade version needed to eliminate matching vulnerabilities, without rate limits or API keys.

MCP server that enables LLMs to operate Acunetix/Invicti web vulnerability scanners through 15 tools, covering authentication, target management, scanning, vulnerability retrieval, and reporting via GraphQL and REST APIs.

Enables any MCP-capable AI to headlessly launch and dynamically instrument Windows executables via IDA Pro's PIN tracer, with tools for breakpoints, register/memory access, execution control, and instruction tracing without opening the IDA GUI.

Enables guided security evaluation of a virtual lab machine, including network scanning, HTTP/TLS analysis, OWASP Top 10 assessment, and Markdown report generation, without performing exploitation.

Enables AI clients to manage ADB devices and packages, detect packers, pull APKs, and unpack hardened Android apps via static extraction, BlackDex, or Frida, then convert DEX files to smali. Supports listing, reading, and regex-searching smali classes to locate APIs and other reverse-engineering targets.

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.

Enables AI agents to symbolically execute binaries and solve them mathematically — unflattening OLLVM control flow, using Z3 and angr to derive exact inputs that reach target branches, tracing taint to dangerous sinks, devirtualizing bytecode VMs, and hot-patching live process memory without touching disk.

Enables MCP-capable LLM agents to control YADS queues, manage tags, and trigger scans through YADS's API-authenticated /api/v1 interface without dashboard access. All actions respect tenant isolation and scan limits.

A security research MCP server for testing tool call safety with deterministic policies like allowlists, path boundary enforcement, SSRF prevention, output redaction, and prompt injection detection, without requiring external LLMs or API keys.

Enables deterministic security testing of AI agents that use tools by serving synthetic MCP environments with poisoned data, fake secrets, and privileged actions. Records agent tool calls and evaluates security invariants (e.g., canary leaks, forbidden access, approval binding) without an LLM judge or real systems.

An MCP server that provides AI assistants with real-time access to Windows internals including processes, kernel traces, event logs, services, drivers, and PE analysis.

Provides local, dependency-free security scanning tools for LLM configurations, prompts, RAG sources, and more, enabling AI coding agents to detect prompt injections and other vulnerabilities without external network access.

Enables local, evidence-first triage of native binaries by extracting bounded symbols, strings, sections, call sites, gadget candidates, and mitigation signals as MCP tools for agent-guided manual review. It also provides metadata-only inspection for carriers such as archives, WebAssembly, firmware, and scripts without claiming verified vulnerabilities.

Enables AI agents to query and act on Microsoft Defender XDR incidents, alerts, advanced hunting data, Entra ID logs, threat indicators, device response actions, and vulnerability management via Microsoft Graph and Defender for Endpoint APIs.

Enables scanning OpenAPI specifications for security gaps and generating security test checklists for APIs.

Enables AI assistants to perform automated security audits on APIs, detecting BOLA/IDOR vulnerabilities by comparing responses across user tokens.

A CTF Pwn AI-assisted debugging platform based on MCP, enabling AI to directly interact with remote GDB and CTF services for automated heap exploitation.