Hashgraph Online · Open source

Open-source security for AI agents.

HOL Guard checks every command, package install and config change your coding agent makes, before it runs. The HOL Plugin Registry scores 50,031 plugins before you install one. Both are built on open standards we publish.

Download HOL GuardBrowse plugins
  • Apache-2.0, source on GitHub
  • Runs locally, works offline
  • 13 coding agents supported
  • Open HCS standards

HOL Guard · review

Claude Code

$ curl -fsSL get.devtool.sh | sh

Runs a script from the internet in your shell.

BlockAllow onceAlways allow

Plugin Registry

A Team

by RBraga01

Trust score91

Owner verified

Registry Broker

GET /api/v1/search?q=translator

20012 agents · 4 registries

Guard downloads
2.5M+
PyPI, Guard and plugin-scanner
GitHub stars
6.1K+
Across HOL repositories
Registry listings
50K
HOL Plugin Registry
Latest Guard release
v3.56.0
Released Oct 24, 2026
Guard works with
Claude CodeCodexCursorGemini CLIOpenCodeand more

What HOL builds

Open infrastructure for the agent ecosystem.

Four products, one goal: make AI agents safer to run, easier to find and simpler to build on.

  • 01

    HOL Guard

    Local security for coding agents. Reviews commands, tool calls and package installs before they run.

    Explore HOL Guard
  • 02

    Plugin Registry

    Plugins, MCP servers and skills for agent tools, each with developer, verification and trust signals.

    Browse plugins
  • 03

    Advertise and sponsor

    Reach developers where they pick tools. Placements from $50 a month, sponsorship from $5,000 a year.

    AdvertiseSponsor
  • 04

    Registry Broker

    One API to find and resolve agents across registries, built on the open HCS standards.

    Open the registry

HOL Guard

See the command before it runs.

Guard sits between your coding agent and your machine. Routine work goes through silently. Anything new or risky stops and asks you, with the reason in plain words.

  1. $ git status && npm test

    Reads and runs your own tests

    Allowed

  2. $ npm install left-pad-utils

    New package, first install

    Asks you

  3. $ cat ~/.aws/credentials

    Reads cloud credentials

    Blocked
Guard PyPI downloads
2.5M+
HOL GitHub stars
6.1K+
See how HOL Guard worksRead the docs
localhost · HOL Guard review
Install on macOS or Linux
$ set -o pipefail; curl -fsSL https://hol.org/guard/install.sh | bash -s -- --mode install --verify$ hol-guard init

Works with

  • Codex
  • Claude Code
  • Copilot CLI
  • Antigravity CLI
  • Cursor
  • OpenCode
  • Hermes
  • OpenClaw
  • Antigravity
  • Kimi
  • Grok
  • Pi
  • Z Code

HOL Plugin Registry

Check a plugin before you install it.

The HOL Plugin Registry lists 50,031 plugins, MCP servers and skills for agent tools. Every listing shows who built it, whether the owner is verified, and a trust score you can compare.

Browse all pluginsBest MCP plugins

  • Agent402

    by Havok Holdings LLC

    Open-source MCP server and x402 seller: 500+ tools for web search, rendering, PDFs, OCR, market and SEC data, paid per call in USDC or free via proof-of-work, no account or API key

    Plugin · Codex

    Owner verified

    Trust

    94

  • AI Command Center

    by Hredo

    Local-first Windows, macOS and Linux command center for Claude Code, Codex, OpenCode, Aider, Gemini CLI, Ollama and 8,000+ API models, with live cost and token analytics (even for Claude Code sessions in other terminals), a side-by-side Arena, real terminals and git per project

    Plugin · Codex

    Owner verified

    Trust

    94

  • ThoughtProof MCP

    by ThoughtProof

    Local MCP pre-action verification for agents: mandate + proposed action → ALLOW/BLOCK/UNCERTAIN; execute only on ALLOW

    Plugin · Codex

    Owner verified

    Trust

    94

  • A Team

    by RBraga01

    A complete engineering team in one folder with 26 specialist agents, 20 workflow skills, an orchestrator, and quality gates; integration and hook support vary by coding platform.

    Plugin · Codex

    Owner verified

    Trust

    91

  • humanizer-ru

    by Ilya Utov

    Agent skill for Claude Code, Codex, Cursor and Gemini that rewrites Russian text to remove 64 AI-generation markers (bureaucratese, calques, ChatGPT fingerprints), with a corpus-calibrated scanner, audit mode and author-voice calibration

    Plugin · Codex

    Owner verified

    Trust

    94

  • Ontoly

    by 0xsarwagya

    Deterministic Software Graph workflows for Codex: architecture review, dependency analysis, request tracing, configuration analysis, and impact analysis.

    Plugin · Codex

    Owner verified

    Trust

    92

  • agent-kit

    by agent-kit-startup

    Extension pack of slash commands, skills, rules, and hooks adding plan-driven, confirmation-gated coding and staging-to-prod git workflows to Cursor and Claude Code

    Plugin · Codex

    Owner verified

    Trust

    92

  • Embedded Workbench

    by Amethyst Luna

    Embedded C/C++ firmware development toolbox — 7 skills (FreeRTOS, Keil MDK, ARMCLANG, HardFault triage, state machines, LVGL) plus workflow gates and 4 agents for Claude Code, Codex, Cursor, Kimi, OpenCode, and ZCode

    Plugin · Codex

    Owner verified

    Trust

    92

Work with HOL

Reach developers. Back open source.

Put your product in front of developers while they pick agent tools, or fund the open-source work they already run.

Advertise

From$50a month

Self-serve placements where developers choose agent tools.

  • Featured slots in the plugin and extension directories
  • Linked logos in HOL project READMEs, including HOL Guard
  • Exact monthly prices and self-serve checkout
See advertising ratesPreview the placements

Sponsor

From$5,000a year

An annual sponsorship of HOL open-source work.

  • A linked logo for 12 months
  • A jointly reviewed announcement on the HOL blog
  • Quarterly written updates on the work you fund
See sponsor offersStart a sponsor inquiry

HOL Registry Broker

Find any agent with one API.

The Registry Broker searches and resolves AI agents across registries and protocols. Every result carries an HCS-14 universal agent ID, so you can address it the same way wherever it lives.

Open the registry
Registry Broker API
GET /api/v1/search?q=translator&limit=2
200Example response, trimmed
{  "total": 12,  "hits": [    {      "name": "Polyglot",      "registry": "hashgraph-online",      "protocols": ["a2a", "mcp"],      "uaid": "uaid:aid:…"    },    …  ]}

Open standards

We publish the standards.

HOL is part of Hiero, the open-source ledger project at the Linux Foundation Decentralized Trust. We write the Hiero Consensus Standards in the open, with partners and working groups. Anyone can read them, implement them, and propose changes.

All HCS standards

Partners and open source

Built in the open.

HOL develops its standards and software in public, together with the organizations in the HOL Partner Program.

About the programOpen-source impact
Founding partners
30+
Working groups formed
12+
GitHub stars across HOL repos
6.1K
Package downloads, last 30 days
333.2K
Join the partner program

FAQ

Questions people ask about HOL.

What is HOL?

HOL, short for Hashgraph Online, is open infrastructure for AI agents. It builds HOL Guard for agent security, the HOL Plugin Registry for finding plugins, MCP servers, and skills, the Registry Broker for agent discovery, and the open HCS standards behind them.

What is HOL Guard?

HOL Guard is a local-first security layer for AI agents. On supported integrations it checks risky actions such as commands, tool calls, package installs, and configuration changes before they run, lets you allow, ask, or block them, and keeps a record of what happened. Install it with the one-line command on this page, then run hol-guard init.

Which AI tools does HOL Guard work with?

HOL Guard connects to Codex, Claude Code, Copilot CLI, Antigravity CLI, Cursor, OpenCode, Hermes, OpenClaw, Antigravity, Kimi, Grok, Pi, Z Code, or a custom agent. How much Guard can intercept depends on what each tool exposes, so check the Guard documentation at hol.org/guard/docs for the coverage of your tool.

What is the HOL Plugin Registry?

The HOL Plugin Registry is a public directory of plugins, MCP servers, and skills for AI agent tools. Each listing shows its developer, category, verification and trust signals, and scan results, so you can compare options before you install one.

How do developers build on the HOL Registry Broker?

The Registry Broker is the HOL API for discovering and resolving AI agents across registries. Start with the documentation at hol.org/docs and the developer hub at hol.org/developers, then call the API described by the OpenAPI document at hol.org/openapi.json and the registry docs at hol.org/registry/docs.

What are the HCS standards?

The HCS standards are open specifications for agent identity, messaging, registries, and trust that HOL and its partners publish. Examples include HCS-10 for agent communication, HCS-14 for Universal Agent IDs, and HCS-26 for agent skills registries. The full list is at hol.org/standards.

How can I advertise to AI developers on HOL?

Advertising on HOL starts at $50 a month for a plugin directory placement and $50 a month for an extension directory placement. See hol.org/advertise for current rates, slots, and how placements are labeled.

How can I sponsor HOL's open-source work?

HOL sponsorship starts at $5,000 a year. The Visibility sponsorship includes a linked company logo on an agreed HOL sponsor or partner page for 12 months, a jointly reviewed announcement on the HOL blog, and quarterly written updates on the open-source work it supports. See hol.org/sponsor for the full offers.

Get started

Put Guard in front of your agent today.

One command installs HOL Guard and connects it to the coding agents on your machine. Free and open source.

Download HOL GuardBrowse pluginsTalk to us
macOS or Linux
$ set -o pipefail; curl -fsSL https://hol.org/guard/install.sh | bash -s -- --mode install --verify$ hol-guard init