The Horde Project

Open Source Groupware and Collaboration Softwarehorde.org

The Horde Project is an open-source community initiative that builds a PHP-based groupware framework and webmail suite, serving self-hosting enterprises, ISPs, and developers who need standards-based email, calendar, contacts, and collaboration tools, funded primarily through corporate sponsorships and professional services.

Company typePrivate
Founded2001
HeadquartersAtlanta, United States
Headcount1–10
GTM typeB2B
OfferingSoftware

What The Horde Project does

The Horde Project is an open-source community project that develops a PHP-based groupware platform consisting of a reusable application framework and a suite of browser-based collaboration applications. Headquartered in Atlanta and founded circa 2001, the project is maintained by a small core team (1–10 personnel) including co-founders Jan Schneider and Michael J. Rubinsky, with developer Ralf Lang contributed via employer B1 Systems. The platform serves self-hosting enterprises, ISPs, and developers who need standards-based email, calendar, contacts, tasks, notes, file management, and wiki functionality without vendor lock-in; its claimed reach extends to millions of end users deployed across hosting providers and on-premise installations.

The product stack is anchored by the Horde Framework, a modular PHP framework, and Horde Groupware Webmail Edition, the integrated suite. Around twenty add-on applications extend the suite, including IMP (mail), Kronolith (calendar), Turba (contacts), Nag (tasks), Mnemo (notes), Gollem (file manager), Ansel (photo gallery), Wicked (wiki), Ingo (mail filters), Whups (ticketing), and Chora (repository browser). The platform supports CalDAV/CardDAV for calendar and contact sync, ActiveSync for mobile device integration, SyncML for legacy mobile sync, and LDAP for identity. Horde 6 is currently in beta (announced 2026), introducing modern PHP support, PHP-FIG standards adoption, hybrid JWT authentication, and a new Two-Factor Authentication API with a One-Time Password module.

Horde operates as a non-commercial open-source initiative: the core product is distributed free of charge under an open-source license, and there is no venture funding or public ownership. Recurring cash inflow comes from a tiered corporate sponsorship program (Bronze $100/month through Platinum $1,000/month) and from quote-based professional services for enterprise installations and custom development. Infrastructure is supported through partnerships with Hub.org (mailing lists, GitHub, Packagist hosting) and B1 Systems (server hosting plus developer time). Sponsors and testimonial customers include Hub.org, B1 Systems, intra2net, PSW GROUP, Synthesis AG (SyncML licensing), and AMMMa AG (affiliated with Jan Schneider); Ubiquity Hosting Solutions and The WebWonker are cited as independent endorsements.

The Horde Project firmographics

Firmographics

Name: The Horde Project
Legal name: The Horde Project
Website: https://horde.org
Company type: Private
Founded year: 2001
Operating status: Operating
Headcount range: 1–10 employees
Short description: The Horde Project is an open-source community initiative that builds a PHP-based groupware framework and webmail suite, serving self-hosting enterprises, ISPs, and developers who need standards-based email, calendar, contacts, and collaboration tools, funded primarily through corporate sponsorships and professional services.
Ownership category
akta.pro rank

The Horde Project industry classification

Industry

Product category: Open Source Groupware and Collaboration Software
NAICS: Software Publishers (5132), Computer Systems Design and Related Services (54151)
SIC: Services-Prepackaged Software (7372), Services-Computer Programming Services (7371)
akta.pro industry: PRIMARYBPAMAMAC
Email, Calendar & Scheduling
Business & Public Services/Web, Mobile & Digital Platforms/Collaboration, Productivity & Work Platforms
SECONDARYBPAMAMAF
Project & Task Management
Business & Public Services/Web, Mobile & Digital Platforms/Collaboration, Productivity & Work Platforms

Keywords

Open source groupware
PHP webmail framework
Collaboration software
Browser-based email suite
Calendar contact management

Where The Horde Project is headquartered

Location

Headquarters

HQ city: Atlanta
HQ country: United States
HQ region: North America

Offices1 record

Markets served

The Horde Project business model

Business model

GTM type: B2B
Offering type: Software
Cost components: Personnel, Technology or R&D, Infrastructure, Operations

Revenue model

Open Source Software Distribution: Free open source software distributed under open source license. Core product is freely available for download and self-hosting.
Professional Services: Team of trusted professionals helps build large installations or custom applications. Consulting and implementation services for enterprise deployments.
Sponsorship and Donations: Monthly sponsorships from Bronze ($100/month) to Platinum ($1,000/month) tiers. Funds support general Horde development and new features.

Pricing tiers

Model	Billing	Price
Freemium	Monthly	Free open source version
Subscription	Monthly	Bronze Sponsor
Subscription	Monthly	Silver Sponsor
Subscription	Monthly	Gold Sponsor
Subscription	Monthly	Platinum Sponsor

Go-to-market motion1 record

Distribution channels4 records

Marketing channels8 records

The Horde Project product offering

Product offering

Core offering

The Horde Project develops and distributes a free, open-source, browser-based communication and groupware suite for managing email, calendars, contacts, tasks, notes, files, and wikis, built on a PHP-based modular framework. It also offers professional services for large enterprise installations and custom application development, and accepts tiered monthly sponsorships to fund ongoing development.

Product overview

The Horde Project is an open-source groupware platform based on PHP and the Horde Framework. The core product is Horde Groupware Webmail Edition, a free enterprise-ready browser-based communication suite. The platform follows a modular architecture where the Horde Framework provides the foundation for multiple add-on applications including IMP (mail), Kronolith (calendar), Turba (contacts), Nag (tasks), Mnemo (notes), Gollem (file manager), Ansel (photos), Wicked (wiki), Ingo (filters), Whups (tickets), Chora (repository), Sesha (inventory), Passwd (passwords), and more. Horde 6 is the upcoming major version in beta, promising support for latest PHP releases and improved CalDAV/CardDAV synchronization.

Differentiator

Problem solved

Functional benefit

Products and services

Horde Groupware Webmail Edition Free, enterprise-ready, browser-based communication suite for sending, reading and organizing email, managing calendars, contacts, tasks and notes with users both inside and beyond their own network, with different interfaces for different devices and synchronization out of the box.
Horde Framework Robust, standards-based PHP application framework that provides the foundation for all Horde applications and enables developers to build custom web applications capable of using existing platforms and backends.
Professional Services Consulting and implementation services for large enterprise deployments of the Horde platform and custom application development on the Horde Framework, quoted per engagement.

Companies that use The Horde Project

Customer profile

Named customers2 records

Segments2 records

Ideal customer profiles2 records

The Horde Project technology and API

Technology

Technology focussed Yes

API detail

Has API: No
API docs
API detail

Core technology

AI maturity

App detail

Integration6 records

Feature6 records

The Horde Project partnerships and signals

Strategic signal

Partnerships

Eight partnerships are on record, tiered core and minor.

Hub.org Networking ServicescoreOthersHub.org provides hosting services for Horde.org servers including mailing lists, GitHub, and Packagist. This is infrastructure support for the open source project.
B1 SystemscoreOthersB1 Systems provides hosting for Horde.org servers and employs developer Ralf Lang who works on Horde development. They also provide sponsorship support.
Synthesis AGminorOthersSyncML client licenses have been generously donated by Synthesis AG for use in Horde synchronization features.
intra2netminorOthersSilver sponsor donating funds to support general Horde development. Listed on the thanks page.
PSW GROUPminorOthersBronze sponsor donating funds to support general Horde development.
topratedbingosites.co.ukminorOthersBronze sponsor donating funds to support general Horde development.
bingo gamesminorOthersBronze sponsor donating funds to support general Horde development.
AMMMa AGminorOthersAward winning e-learning and knowledge management solutions company co-founded by Jan Schneider, core developer and founding member of Horde.

Scale indicators1 record

Recent moves6 records

Expansion highlights4 records

The Horde Project competitors and assessment

Company assessment

Emerging players

iRedMail: Open source mail server solution bundling Postfix/Dovecot with a webmail frontend (often Roundcube) and optional groupware components. Comparable as an alternative open source email/collaboration stack that overlaps with Horde's webmail use case.

Direct peers

Open-Xchange: Provider of OX App Suite, an open source email, calendar, contacts, and document platform targeted at ISPs, telcos, and enterprises. Direct competitor in the standards-based, self-hostable groupware category.
Nextcloud: Open source, self-hosted collaboration suite (calendar, contacts, mail, files, talk) built on PHP. Direct competitor in the on-premises groupware category Horde serves, with overlapping standards-based sync and a much larger contributor base.
Zimbra: Open source email and collaboration platform offering webmail, calendar, contacts, and tasks for service providers and enterprises. Competes head-on with Horde Groupware Webmail Edition for hosting-provider and on-prem deployments.
BlueMind: Open source messaging and collaboration platform (mail, calendar, contacts, mobile sync) targeted at European enterprises and public sector. Competes in the same self-hosted, standards-based groupware category as Horde.
Kolab Systems: Open source Kolab Groupware Server offering shared calendars, contacts, tasks, and notes, and a documented integration partner for Horde. Competes in the same privacy-focused, self-hosted segment.
eGroupware: Open source groupware suite (calendar, email, CRM, projects) primarily used in European SMBs and public sector. Direct competitor in the open source, self-hosted collaboration category.
Citadel: Open source groupware platform combining email, calendaring, address books, and bulletin boards in a single self-hostable server. Comparable as a community-driven, all-in-one alternative to Horde.
SOGo: Open source groupware server with Webmail, CalDAV, CardDAV, and ActiveSync support. Targets the same self-hosted enterprise and ISP use cases as Horde and uses similar standards-based sync protocols.
Roundcube: Open source PHP-based webmail client with calendar/contacts plugins. Closely comparable as a free, browser-based email/collaboration tool often deployed alongside or instead of Horde's IMP module.

Market position

Strengths4 records

Weaknesses4 records

Competitive moat4 records

Key risks5 records

Key highlights5 records

Customer concentration

The Horde Project financial estimates

Financial estimate

Revenue estimate

Valuation estimate

The Horde Project leadership team

Management profile

Number of profiles

Profiles3 records

The Horde Project funding detail

Funding detail

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

The Horde Project M&A and investment

M&A and investment

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about The Horde Project

What does The Horde Project do?

Is The Horde Project a public or private company?

The Horde Project is a private company. It is classified as founder individual operated bootstrapped and is currently operating.

When was The Horde Project founded?

The Horde Project was founded in 2001. It employs 1 to 10 people.

Where is The Horde Project based?

The Horde Project is headquartered in Atlanta, United States, in the North America region.

How does The Horde Project make money?

Three revenue lines are on record. Open Source Software Distribution is the primary driver. The others are professional Services and sponsorship and Donations.

Who are The Horde Project's main competitors?

iRedMail is listed as an emerging player. Direct peers are Open-Xchange, Nextcloud, Zimbra, BlueMind, Kolab Systems, eGroupware, Citadel, SOGo and Roundcube.

Does The Horde Project have an API?

No public API is recorded for The Horde Project.

What industry is The Horde Project in?

The Horde Project's product category is Open Source Groupware and Collaboration Software. Its primary akta.pro industry code is BPAMAMAC, Email, Calendar & Scheduling, with a secondary code of BPAMAMAF, Project & Task Management. Its NAICS code is 5132 and its SIC code is 7372.