YaCy peer-to-peer search

Name: YaCy peer-to-peer search
Author: pad01g

by pad01gversion 1.0.0i★ –iRuns on your computer

Registry nameio.github.pad01g/yacy-search

Install

Overview

Description from the maker (original English)

Web search, crawling and ranking evaluation on your own YaCy peer: no API key, no central service.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiVery new★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Search & AI memory
You need to fill in: YACY_URL, YACY_ADMIN_PASSWORD

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
You fill in yourself: YACY_URL, YACY_ADMIN_USER, YACY_ADMIN_PASSWORD, YACY_CRAWL_ALLOW_PRIVATE, YACY_ALLOW_TRUST_SETTINGS

Values marked secret are keys to your account. Never share them or paste them into a chat.

You need

DockerDocker installed

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "yacy-search": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e",
        "YACY_URL",
        "-e",
        "YACY_ADMIN_USER",
        "-e",
        "YACY_ADMIN_PASSWORD",
        "-e",
        "YACY_CRAWL_ALLOW_PRIVATE",
        "-e",
        "YACY_ALLOW_TRUST_SETTINGS",
        "ghcr.io/pad01g/yacy-search-mcp:1.0.0"
      ],
      "env": {
        "YACY_URL": "your-value",
        "YACY_ADMIN_USER": "your-value",
        "YACY_ADMIN_PASSWORD": "your-value",
        "YACY_CRAWL_ALLOW_PRIVATE": "your-value",
        "YACY_ALLOW_TRUST_SETTINGS": "your-value"
      }
    }
  }
}

Run this in your terminal

claude mcp add yacy-search --env YACY_URL=your-value --env YACY_ADMIN_USER=your-value --env YACY_ADMIN_PASSWORD=your-value --env YACY_CRAWL_ALLOW_PRIVATE=your-value --env YACY_ALLOW_TRUST_SETTINGS=your-value -- docker run -i --rm -e YACY_URL -e YACY_ADMIN_USER -e YACY_ADMIN_PASSWORD -e YACY_CRAWL_ALLOW_PRIVATE -e YACY_ALLOW_TRUST_SETTINGS ghcr.io/pad01g/yacy-search-mcp:1.0.0

Fill in the empty values before running it.

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "yacy-search": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e",
        "YACY_URL",
        "-e",
        "YACY_ADMIN_USER",
        "-e",
        "YACY_ADMIN_PASSWORD",
        "-e",
        "YACY_CRAWL_ALLOW_PRIVATE",
        "-e",
        "YACY_ALLOW_TRUST_SETTINGS",
        "ghcr.io/pad01g/yacy-search-mcp:1.0.0"
      ],
      "env": {
        "YACY_URL": "your-value",
        "YACY_ADMIN_USER": "your-value",
        "YACY_ADMIN_PASSWORD": "your-value",
        "YACY_CRAWL_ALLOW_PRIVATE": "your-value",
        "YACY_ALLOW_TRUST_SETTINGS": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "yacy-search": {
      "type": "stdio",
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e",
        "YACY_URL",
        "-e",
        "YACY_ADMIN_USER",
        "-e",
        "YACY_ADMIN_PASSWORD",
        "-e",
        "YACY_CRAWL_ALLOW_PRIVATE",
        "-e",
        "YACY_ALLOW_TRUST_SETTINGS",
        "ghcr.io/pad01g/yacy-search-mcp:1.0.0"
      ],
      "env": {
        "YACY_URL": "your-value",
        "YACY_ADMIN_USER": "your-value",
        "YACY_ADMIN_PASSWORD": "your-value",
        "YACY_CRAWL_ALLOW_PRIVATE": "your-value",
        "YACY_ALLOW_TRUST_SETTINGS": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

Values you fill in

YACY_URL required env
Base URL of your YaCy peer as seen from the MCP server container, e.g. http://yacy:8090 on a shared Docker network (docker run --network ...), or http://host.docker.internal:8090
YACY_ADMIN_USER env
YaCy administrator account, needed for crawling and settings
YACY_ADMIN_PASSWORD secret env
YaCy administrator password; without it crawl, settings and the index counts of index_status are not available
YACY_CRAWL_ALLOW_PRIVATE env
1 lets crawl reach loopback and private addresses (intranets); off by default
YACY_ALLOW_TRUST_SETTINGS env
1 lets set_ranking_setting change the trust filter settings (acceptUnverified, excludeTags); off by default

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 8, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account pad01g, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Search & AI memoryi

More stars than 0% of the other 5716 servers in this category
Published to the registry more recently than 51% of the other 5716 servers in this category
Basic checks equal to or better than 100% of the other 5716 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is YaCy peer-to-peer search safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

You need to fill in: YACY_URL, YACY_ADMIN_PASSWORD

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (1.0.0) reached the registry 38 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Docker on your computer.

What can I use instead?

In the same category: Context7, Codebase Memory, Exa

Alternatives

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Reading a card:↓ Downloads per weeki★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

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Exa

Connect AI agents to Exa for web search, content fetching, and multi-step research.

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Runs in the cloud✓ exa.ai

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

yacy-search MCP server

An MCP server for one YaCy peer: web search without a search API or API key, crawling, ranking settings and search quality evaluation. It runs next to the agent (stdio) and talks to the agent's own peer over HTTP. There is no central service: the peer is yours, and it searches the peer-to-peer network it belongs to. Registry name: io.github.pad01g/yacy-search.

It is written for the improved-search fork (results carry author signature verdicts and tags). Search, crawl, status and settings also work with upstream YaCy.

Run

Start a peer and the MCP server on one Docker network:

docker network create yacy 2>/dev/null || true

docker run -d --name yacy --network yacy -p 127.0.0.1:8090:8090 \ -v yacy_data:/opt/yacy_search_server/DATA ghcr.io/pad01g/yacy-improved-search:latest

Claude Code

claude mcp add yacy -- docker run -i --rm --network yacy \ -e YACY_URL=http://yacy:8090 -e YACY_ADMIN_PASSWORD=' ' ghcr.io/pad01g/yacy-search-mcp:1.0.0

The fork's image starts with the administrator account admin / yacy: change the password at http://127.0.0.1:8090/ConfigAccounts_p.html before connecting the MCP server, and pass the new one.

Other clients (mcp.json style):

"mcpServers": { "yacy": { "command": "docker", "args": ["run", "-i", "--rm", "--network", "yacy", "-e", "YACY_URL=http://yacy:8090", "-e", "YACY_ADMIN_PASSWORD= ", "ghcr.io/pad01g/yacy-search-mcp:1.0.0"] } } }

For a peer outside Docker use -e YACY_URL=http://host.docker.internal:8090 (Linux: add --add-host=host.docker.internal:host-gateway). Without Docker: npm ci && node src/server.ts in this directory (Node 24).

Variable	Default	Meaning
`YACY_URL`	`http://localhost:8090`	base URL of the peer
`YACY_ADMIN_USER`	`admin`	administrator account (crawl, status counts, settings)
`YACY_ADMIN_PASSWORD`	unset	administrator password; without it `crawl_site`, `control_crawl`, `delete_document` and `set_ranking_setting` are refused (even if the peer accepts local requests without a password), and the reading admin tools work only where the peer allows them without one
`YACY_CRAWL_ALLOW_PRIVATE`	unset	`1`: `crawl_site` may reach loopback and private addresses (an intranet). Otherwise only http(s) URLs of public hosts. This checks the start URL only; the links and redirects YaCy follows are limited by YaCy's own `network.unit.domain` (`global` on public peers refuses local addresses)
`YACY_TIMEOUT_MS`	`30000`	timeout of one request to the peer
`YACY_ALLOW_TRUST_SETTINGS`	unset	`1`: `set_ranking_setting` may also change `trust.search.acceptUnverified` and `trust.policy.excludeTags`

On the improved-search fork, the vector search (short questions find pages without the exact words) is used only for searches of the peer's administrator or from its host. When the MCP server runs in another container, set search.vector.public=true on the peer (it then embeds every new query of its search page).

Tools

Tool	What it does
`search_web`	full-text search; `resource: "global"` also asks connected peers and waits `waitMs` before ranking all answers
`crawl_site`	start a crawl (`url`, `depth`, `range`: domain / subpath / wide, `maxPages` per host, default 200)
`get_index_status`	indexed documents, crawl queues, peer type and connections; explains a paused crawler (load average) and a peer without a public address
`list_peers`	connected peers: signed seed, reach (direct / relay), tags
`get_ranking_settings`	the ranking and filtering settings with their meaning
`set_ranking_setting`	change one of them (allow-list only: minimum match, coverage and thin page weights, title phrase boost, wait time; unverified results and excluded tags only with `YACY_ALLOW_TRUST_SETTINGS=1`)
`evaluate_ranking`	queries with known relevant URLs: precision@k, recall@k, R-precision, the rank of each relevant URL; finishes within about 50 s (queries that do not fit are reported as `skipped`)
`get_trust_status`	the signed delegations and peer lists the peer holds
`list_crawls`	the crawls started on the peer, with the handle `control_crawl` needs
`control_crawl`	pause or resume the local crawler, or stop one crawl (indexed pages stay)
`delete_document`	remove one page from the peer's own index (stop a running crawl of that site first)

1.0.0 renamed the tools to a consistent verb_noun form (no aliases): search → search_web, crawl → crawl_site, crawls → list_crawls, crawl_control → control_crawl, index_status → get_index_status, peers → list_peers, trust_status → get_trust_status. Clients that call tools by name need the new names.

A typical loop for improving results: evaluate_ranking → set_ranking_setting → evaluate_ranking.

Titles and snippets come from page authors and other peers: the tool descriptions tell the model to treat them as data, not instructions. crawl_site, control_crawl, delete_document and set_ranking_setting are marked destructive so that clients ask before calling them. Values of settings are checked per key, and a value YaCy stores differently is rolled back.

Test

npm ci && npm run typecheck && npm test                      # unit tests

YACY_URL=http://localhost:8090 YACY_ADMIN_PASSWORD=yacy npm test # also calls every tool on a live peer

License

This directory (the MCP server) is under the MIT license. It talks to YaCy only over HTTP and contains no YaCy code; the rest of this repository, YaCy itself, stays under the GPL.

YaCy peer-to-peer search

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

Values you fill in

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Search & AI memoryi

Common questions

Alternatives

Context7

Codebase Memory

Exa

README from the maker

yacy-search MCP server

Run

Claude Code

Tools

Test

License