YaCy review: a search index you run yourself

YaCy is a free open-source search engine you install on a computer you control. It keeps a search index, a list of pages and the words on them, and it gives you a search box in your browser. It suits anyone who wants to search a website, a home or office network, or a set of pages they choose, without sending every query to a large search company. You can share that index with other YaCy users, or keep it on your own machine.¹³

Last checked October 28, 2026.

At a glance

What it is: Free search-engine software for a local index, an organization portal, or a shared peer-to-peer index.¹

Works on: Windows, macOS, and Linux, including Docker. Not on phones. Java 17 or newer, unless you use Docker.²

Price: Free to download and run. The project asks for donations and also offers consulting.¹

Licence: GPL version 2 or later. Files under source/net/yacy/cora are LGPL version 2 or later.³⁴

Best for: A website, intranet, or personal crawl on a computer you can leave running.

Official site: yacy.net

What YaCy does (and how it protects your privacy)

YaCy stores the index, shows a search page, and includes a crawler, a program that follows links, with a scheduler so the index can stay fresh. It can run on an intranet, a private office or home network, and scan for HTTP, FTP, and SMB servers.³

The default is a public peer-to-peer network: the peers are equals, they share an index, and the homepage says there is no central point and no storage of search requests. Your copy still asks other peers, then keeps those results locally. Sharing stays on until you switch it off. That private setup is called Robinson mode. For your own site, turn off DHT distribution and DHT receive. A DHT (distributed hash table) is how index words are spread across peers. If a firewall or router means others cannot reach you, YaCy calls the peer junior: it may still send index files out, but search uses the local index only.¹³⁵⁸

Key features

Your own index. The index, the search page, and the crawler run on a machine you manage.³
Public network or private search. Joining the shared cluster is the default. You can opt out, or search only the local index.³
Site, intranet, and file search. Crawl your website, or scan an internal network for HTTP, FTP, and SMB servers.¹³
No extra database. Solr, the search database, is built in. You can use an external Solr server if you already have one.⁵
A page on your computer. After startup, open http://localhost:8090. On this computer, admin pages need no password.²
Filters, and a disk cap. inurl: filters by web address. /date sorts by when a page was indexed. You can cap the cache in megabytes. The global index is shared, not copied onto every peer.⁵

Pros and cons

Pros

The index sits on hardware you choose. The README says privacy was the priority reason YaCy was created.³
The software is free. The source is GPL version 2 or later, with the cora files under the LGPL.¹⁴
A local-only search is computed from this copy’s index.³
Password-protected pages, cookie pages, and pages loaded with GET or POST parameters are left out of the index by default.⁵
Version 1.942 packages are dated 15 August 2026, and the source has commits on 23 September 2026.⁶⁷

Cons

No phone app. It runs on desktops and servers, and needs Java 17 unless you use Docker.²
The first run joins the public network, and index sharing stays on until you change it. A junior peer can still send index files out.³⁵⁸
The public index is only what peers have crawled. With few peers, the FAQ says YaCy cannot match Google.⁵
The FAQ calls YaCy resource hungry. A fast disk and plenty of RAM help.⁵
From another device the first login is admin, password yacy. Change it before you expose YaCy on a network.²

Is YaCy safe and private?

The project site says YaCy does not collect personalized data and has no phoning-home, meaning it does not report back to a vendor. The source is public. The README names Michael Peter Christen as maintainer, including for paid customization. A private company owns the brand. The homepage calls the software project non-profit and also offers consulting.¹³

On the public network your copy asks other peers for results. The homepage says there is no central point and no storage of search requests. The FAQ says there is no central server. The FAQ says four seed-list servers are hard-coded into the source. Received results are stored on your peer.¹⁵ Opening a result is an ordinary visit to that website. A guide to what your internet provider can still see covers that part of the path.

As a proxy, a go-between for pages you open, YaCy may index them. Password- and cookie-protected pages are excluded, and pages loaded with GET or POST parameters are skipped by default. The FAQ says a peer’s stored pages cannot be browsed as a history. From another device the login starts as admin / yacy. Change it before YaCy is reachable on a network.²⁵

How to get started

Use a computer, not a phone. Install Java 17 or newer, unless you use the Docker image yacy/yacy_search_server:latest. On Windows the guide suggests Temurin.²
Download from the install page or release.yacy.net. The newest files there are version 1.942, dated 15 August 2026 (Windows .exe, macOS .dmg, Linux .tar.gz). Skip yacy_latest, last modified on 2 December 2024. Docker is the ready-to-run package. Git is how you build the newest source.²³⁶
Start YaCy. On Linux, unpack the archive and run ./startYACY.sh. On Windows and macOS, open the installed app. Then go to http://localhost:8090.²
On this computer the admin pages open with no password. From another device the account is admin and the password is yacy, including under Docker. Set a new password before the service is reachable from the network.²³
Sharing starts on. To search only this computer, pick another operation mode or a local-only search. For your own site, turn off DHT distribution and DHT receive.³⁵⁸
Start a crawl of a site you may index, or of pages on your own network, then type a query. If the peer has never contacted the network, YaCy calls it virgin, or offline, and search uses the local index only.⁵

Who should use YaCy (and who might prefer something else)

YaCy fits people who will run a computer and want the index in their own hands: a website, shared folders, or an intranet. On the public network, results come from the indexes peers have built together.⁵

If you want a search box without installing software, see Marginalia Search for the noncommercial web, or MetaGer, a nonprofit metasearch. Pick YaCy when the pages are yours.

Frequently asked questions

Is YaCy free?

Yes. The homepage calls YaCy free software. It also asks for donations and offers consulting. The source is GPL version 2 or later, except the cora files, which are LGPL version 2 or later.¹⁴

Is YaCy safe?

The project says it does not collect personalized data and has no phoning-home. Password- and cookie-protected pages are not indexed. Sharing starts on, a public search asks other peers, and a remote login begins as admin / yacy until you change it.¹²⁵⁸

Does YaCy work on iPhone?

No. YaCy runs on desktops and servers, not on phones. Use Windows, macOS, Linux, or Docker, then open the search page on that computer.²

Can YaCy search without sharing my index?

Yes. Leave the public cluster, or run one search on the local index only. Results then come from that index. For your own site, turn off DHT distribution and DHT receive. A peer that has not contacted the network yet can still search what it has stored.³⁵