Popular Open Source Ticketing Systems

In an era of increasing service demands, companies, authorities, and support teams are looking for flexible, cost-effective, and secure ways to efficiently handle customer inquiries. Open-source ticketing systems offer exactly that: license-free software with full access to the source code, an active community, and countless integration and extension possibilities.

In this comprehensive comparison, we take a look at the best-known solutions – OTOBO, Znuny, OTRS (Community Edition), and Zammad – and introduce other relevant systems such as osTicket, GLPI, and KIX. We analyze features, usability, integrations, hosting options, AI features, and much more.

Whether it's a small business with few support staff or a large IT service desk with complex workflows: this guide shows which open-source ticketing system fits your requirements – and how to successfully implement it. We also incorporate modern AI solutions like Open Ticket AI to elevate classification, prioritization, and automation in the helpdesk to a new level.

Comparison of Open Source Ticketing Systems

Below is a tabular comparison of the mentioned ticketing systems with their key features:

Feature	OTOBO	Znuny	OTRS (Community Edition)	Zammad
License & Open Source Status	GPL v3 (fully open source); fork of OTRS 6 Community Edition, further developed by Rother OSS.	GPL v3 (fully open source); official OTRS 6 successor, maintained by Znuny GmbH / OTTER Alliance.	Open source (GPL) up to version 6; proprietary from OTRS 7/8 onwards (only commercially available).	AGPL v3 (fully open source, guaranteed by Zammad Foundation); developed since 2016.
UI/UX (Modernity & Usability)	Agent interface based on OTRS, customer portal modernized and redesigned (more intuitive, cleaner). Responsive design. Overall more user-friendly due to optimized forms.	Revised UI from Znuny 7: modern, clean design with improved usability. Agent UI remains familiar; customer frontend is contemporary. Before version 7, classic OTRS look.	OTRS 6: feature-rich web interface, visually outdated by now. OTRS 8 (proprietary) with UI updates, but not freely available.	Very modern, appealing web interface. Intuitive operation. Single-page app with live updates (WebSockets). Integrated knowledge base, responsive GUI.
AI Features & Automation	Classic automation via Generic Agent. Optional AI plugin for automatic ticket classification/prioritization (Machine Learning). Planned "OTOBO AI Assistant".	Automation via Generic Agent, process management, templates. No integrated AI out-of-the-box; connection to external AI possible via API/add-ons.	Generic Agent, process management, and templates available. No AI features in the Community Edition.	AI features such as ticket summarization and AI-powered text editor for response assistance. Language detection; extensive automation (triggers, macros).
Integrations (LDAP, Email, API, Plugins)	LDAP/AD, Email (POP3/IMAP/SMTP). REST & SOAP API. Many add-ons via package manager (e.g., OpenStreetMap, i-doit CMDB, PowerBI). GenericInterface for external systems.	Like OTRS CE: LDAP, Email, GenericInterface (REST/SOAP). New Search API with Elasticsearch integration. Many packages/modules (FAQ, ITSM). SSO (Kerberos/AD).	LDAP/AD, Email, SOAP API; later also REST API. Large selection of OTRS packages (FAQ, ITSM, Report). No new integrations; migration to Znuny/OTOBO recommended.	Broad multi-channel integration: Email, Chat, Phone, Twitter, Facebook. REST API and Webhooks; LDAP/AD support.
Hosting Options (Self-Hosted, Cloud, Docker)	Self-hosted (Linux/Perl) or Containers: Official Docker images; Kubernetes deployments possible. No official SaaS, hosting/support via partners.	Primarily Self-hosted. Community Docker images available; no official container deployment. Hosting/support via Znuny GmbH/partners.	Self-hosted standard; community Dockerfiles existed. After EOL of CE, no updates – for new installations, use Znuny/OTOBO.	Very flexible: Self-hosted (packages, Docker-Compose) and Cloud (official SaaS). On-premise identical to cloud. From version 7 onwards, only PostgreSQL.
Extensibility & Community Support	High extensibility, modular design, package manager. Active German-speaking community and DE/EN docs. Regular updates; commercial support available.	Very active community (forums/Discord), OTTER Alliance. Many add-ons compatible. Focus on LTS, stability, and backward compatibility. Commercial services available.	Large historical user base; community support mainly in the forks. OTRS AG focuses on proprietary suite. Switching to Znuny/OTOBO recommended.	Strong community and foundation. Extensions via API/integrations; some premium add-ons. Active forums/GitHub.
Target Audiences & Use Cases	Companies of all sizes; IT service desk, customer support, authorities; ITIL processes via ITSM modules; popular for OTRS migrations and Docker operation.	For existing OTRS users/large organizations focusing on stability, LTS, compliance, and complex workflows; high customizability.	Historically widespread; today mainly relevant for existing installations; new users should choose forks.	From SMB to Enterprise; modern multi-channel experience, popular in B2C customer service and IT support; AI automation.
Language & Docs	Multilingual (>30). Documentation DE/EN. OTOBO Documentation. Active German-speaking community.	UI in many languages; docs primarily EN, numerous DE resources in community/partner environment.	Multilingual (>30). Admin docs of CE v6 in EN; new docs proprietary; fork docs (Znuny/OTOBO) current.	UI in >40 languages; docs primarily EN; community wiki/blog partly DE; internationally oriented.

Note: OTRS here refers to the OTRS Community Edition (Version 6), as newer OTRS versions are not freely available. Znuny and OTOBO originated as forks of this last free OTRS version and continue its open-source development.

Details on Individual Ticketing Systems

Below, we highlight the mentioned ticketing systems individually and discuss their particular strengths.

OTOBO – Modern OTRS Fork from Germany

OTOBO is a ticketing system based on the OTRS 6 Community Edition, initiated by the company Rother OSS. It targets companies of all sizes looking for a flexible, self-hosted helpdesk system. Compared to the original OTRS, OTOBO brings some improvements: notably a modern web frontend. The customer portal has been completely redeveloped and is now much more intuitive and contemporary. OTOBO also performs well on mobile devices thanks to its responsive design.

Functionally, OTOBO covers all classic helpdesk areas – from ticket creation, SLAs, escalation management to knowledge base and self-service portal. Automations can be implemented via the Generic Agent as well as ticket templates and auto-replies. A unique selling point is the available AI plugin for ticket classification, which uses machine learning to pre-sort incoming tickets by category/priority. This relieves the support team through AI automation (keyword AI Automation).

In terms of integrations, OTOBO impresses with its openness: LDAP integration for users, REST and SOAP interfaces, as well as an add-on package manager facilitate the integration of external tools. For example, plugins exist for map display (OpenStreetMap) or linking with a CMDB (e.g., i-doit). A two-factor authentication system (2FA) is also integrated, enhancing security.

Installation & Hosting: OTOBO can be classically installed on Linux (e.g., Debian/Ubuntu), but requires some Perl modules and knowledge. Thanks to official Docker containers, the initial installation is significantly easier – an advantage over the original OTRS. Kubernetes support is also planned. There is no official SaaS offering, but various service providers (such as SoftOFT itself) offer managed hosting and support, which can be attractive for smaller companies that do not want to manage the operation themselves.

Community & Support: As an open-source project, OTOBO has a growing community. The documentation is extensive and available in German (see the OTOBO Documentation), which simplifies onboarding, especially in German-speaking regions. Users exchange best practices in the SoftOFT forum. Commercial support is available directly from Rother OSS or partner companies if professional services are needed. Overall, OTOBO appeals to users who liked OTRS but want a more modern UI and current features – and are willing to support a still relatively new fork community.

Znuny – The Official Successor to the OTRS Community Edition

Znuny emerged in early 2021, immediately after OTRS AG discontinued the free version. It was launched by a consortium of German IT service providers, the OTTER Alliance, with the goal of maintaining OTRS 6 as a fork in the long term. One of the initiators is interestingly OTRS co-founder Martin Edenhofer himself. Znuny can thus be considered the direct successor to the OTRS Community Edition – including Long Term Support (LTS) and a regular release cycle for new features and security updates.

In version 6.x, Znuny largely kept the interface and functionality stable (allowing for an easy upgrade from OTRS 6). However, in 2023, Znuny 7 brought a major step forward: the user interface was modernized and updated in design. Agents can still find their way around but benefit from better usability and accessibility. The customer portal also received a fresh coat of paint. This allows Znuny to catch up somewhat in terms of UI with newer tools.

Znuny offers extensive functionality for tickets, similar to OTRS: queue and role management, escalations, FAQ module, etc. Complex workflows can be mapped through process management extensions – Znuny has even made further improvements here in newer versions. AI features are not integrated by default, but Znuny can be coupled with external AI services thanks to its open interfaces, if desired. The project's priority is rather stability and security: for example, additional compliance and security options have been implemented.

For integrations, Znuny uses the proven GenericInterface from OTRS (SOAP/REST). A new Elasticsearch integration has been added: via a plugin, search indexes can be connected to enable, for example, an external search backend or advanced dashboard analytics (via Grafana). Otherwise, what was integrable in OTRS is also possible in Znuny – from LDAP to external authentication to network monitoring interfaces. The availability of add-on packages (FAQ, ITSM, etc.) remains guaranteed; Znuny provides compatible package repositories.

Deployment: Like OTRS, Znuny is primarily designed for Linux servers. The installation requires a Perl environment, web server, and database, but is routine for experienced administrators. Official Docker images were not available initially, but the community has published Dockerfiles, and since Znuny 6.5, there are best practices for container operation in the community. The core team itself focuses on classic installations and LTS packages. Companies can also use support contracts or hosting with Znuny partners (e.g., maxence, it-novum).

Community: Znuny benefits from a very vibrant community. There is an active forum as well as a Discord channel for developers and users. The OTTER Alliance ensures that resources and knowledge are shared – joint community meetings and webinars keep the user base engaged. As Znuny is used worldwide (downloads come from outside Europe to approx. 25%), communication is mostly in English, but German-speaking help is also available. Overall, many former OTRS users choose Znuny to continue seamlessly, and new users with high demands for customization and support are also well-served here.

OTRS (Community Edition) – The Veteran (up to Version 6)

For many years, OTRS (Open Ticket Request System) was the synonym for open-source ticketing systems. The free Community Edition up to version 6.0 was used in countless companies and organizations. OTRS was characterized by its enormous functional variety and flexibility – from multi-tenancy capabilities and ITIL processes to customization via Perl modules and package systems. More than 30 languages, numerous integrations (e.g., Active Directory, database connectors), and a modular design made OTRS very universal. Many helpdesk features that are now standard originated in OTRS.

However, OTRS AG, the company behind OTRS, announced in late 2020 that it would discontinue the free version. Since then, new features are only released in the proprietary OTRS Suite (versions 7 and 8). The last OTRS Community Edition 6 no longer receives updates, leaving known security vulnerabilities unpatched. For this reason, both experts and the OTRS community itself recommend switching to forks like Znuny or OTOBO, which maintain and improve the code.

For existing installations of OTRS 6, migration paths are still available: Both Znuny and OTOBO allow for a largely lossless transfer of the database and configuration. The switch is worthwhile, as it allows users to continue benefiting from security updates and new features without sacrificing the open-source advantages. Therefore, anyone considering OTRS should practically choose one of the successors directly, as OTRS itself is no longer being developed as an open-source product.

Nevertheless, OTRS as a term still has a strong appeal – many search for "free ticketing systems like OTRS". The good news: With Znuny and OTOBO, there are two worthy open-source heirs ready to meet this demand. And for those who prefer a slightly different approach, Zammad, created by an OTRS co-founder, brings fresh air to the helpdesk world.

Zammad – Modern Helpdesk with All the Trimmings

Zammad is a relatively young open-source ticketing system (first released in 2016) that has relied on modern web technologies from the start. The name Zammad means "together" in Bavarian dialect, and this system perfectly masters bringing together various channels: email, web forms, live chat, phone, social media (Twitter, Facebook) – everything can be bundled and processed centrally in Zammad. This multi-channel orientation makes Zammad particularly attractive for customer service teams that want to be reachable across multiple platforms.

The user interface of Zammad is often praised: it is clear, quick to learn, and updates in real-time. Agents see new updates immediately without reloading the page, thanks to WebSocket technology. The interface looks like a modern web app and is available in numerous languages (over 40). End-users also benefit from an appealing self-service portal and a knowledge base integrated into Zammad.

Feature-wise, Zammad covers all essentials: ticket management with priorities, assignments, attachments, notes; user and permission management with roles; as well as statistics/reporting. It also features sophisticated search (Elasticsearch-based) for quick results. In Zammad, administrators can automate workflows with triggers and macros (e.g., automatic replies or ticket assignments based on specific keywords). Newer versions even include built-in AI features: Zammad can optionally generate a summary of a ticket, which is extremely helpful for long threads. Response formulation is also supported by AI – if you highlight text in the reply field, Zammad can, for example, simplify, make more polite, or make more detailed. These Smart Reply features are optional and show that Zammad is at the forefront of AI automation.

The integration of external systems is primarily done via the API. Zammad offers a REST API that allows almost anything to be controlled remotely (create tickets, read data, synchronize users, etc.). Additionally, there are connectors for CRM systems or VoIP phone systems, for example – call detection can be integrated, which automatically opens the corresponding ticket when a customer calls. Such integrations are invaluable in everyday helpdesk work and are usually uncomplicated to configure. Zammad itself does not (currently) have a plug-in system in the OTRS sense, but due to the openness of the code, third-party providers have been able to provide extensions (e.g., a plugin for SMS dispatch or a WordPress connector for the chat widget).

Deployment: Zammad can be self-hosted – there are packages for Ubuntu, Debian, etc., and also Docker-Compose templates to get started quickly. Alternatively, Zammad GmbH offers cloud hosting (SaaS). This flexibility is helpful: small companies without their own server capacity choose the cloud, while larger or data-sensitive organizations can operate Zammad on-premise. Important: Both variants are based on the exact same open-source version, meaning there is no vendor lock-in. The Zammad Foundation ensures that the project remains free.

Community & Support: Zammad now has a broad user base worldwide. Project maintenance is transparently handled via GitHub, where contributions from the community regularly flow in. For questions, there is an active forum (community.zammad.org) with developers and experienced users. Official documentation is available online (currently mainly in English, but very detailed). For professional needs, Zammad GmbH offers support contracts, training, and possibly enterprise add-ons, but the open-source version is already fully equipped. With the founding of the Zammad Foundation, a strong statement was made that Zammad will remain free helpdesk software in the long term.

Other Open Source Ticketing Systems

Besides OTOBO, Znuny/OTRS, and Zammad, there are several other popular open-source ticketing systems and helpdesk tools that are worth considering depending on your requirements:

• osTicket: A PHP-based, long-established ticketing system. osTicket is completely free (GPL license) and particularly interesting for smaller companies as it is very easy to set up and use. It offers an email-to-ticket function, a simple web portal for customers, and basic features (priorities, SLA, attachments). UI/UX are not as modern as Zammad's, but osTicket convinces with its simplicity and low barriers to entry. Many use it as a lightweight alternative to more complex solutions.

• GLPI: Originally from France, GLPI is a combination of IT asset management and helpdesk. It is open source (GPL) and particularly popular in IT departments that want inventory of hardware/software alongside tickets. GLPI includes a ticketing system for support requests, including a knowledge base and SLA management. UI/UX have improved, but GLPI is primarily aimed at IT administrators who need a comprehensive overview of their infrastructure plus tickets.

• KIX: Another OTRS fork, originating from the KIX4OTRS project by cape IT. KIX has evolved into an independent product focused on IT Service Management. It includes advanced modules for, e.g., maintenance planning, but is also freely available (AGPL). KIX differs slightly in its interface from OTRS and is mainly used in German-speaking countries. For organizations looking for an OTRS-based ITSM with extras, KIX can be an option. However, KIX further developments are sometimes only available to paying customers (open-core model).

• Request Tracker (RT): A classic open-source ticketing system (Perl-based, from BestPractical). RT is very stable and text-heavy but comes without graphical frills. It is suitable for organizations that primarily need email-driven issue tracking (e.g., in universities or for developer support). The learning curve is a bit steeper and the UI is not as modern, but RT is known for its robust performance with many tickets.

• Others: There are numerous other free ticketing systems such as UVdesk (PHP/Laravel-based with an interesting multichannel approach), Helpy (Ruby on Rails, incl. forum function), OTRS Community Edition Forks in other forms (like ((OTRS)) Community Edition at otrscommunityedition.com, which basically corresponds to Znuny). Open-source project management tools like Redmine or OTRS-like solutions could also be repurposed, but the ones listed above are the most prominent representatives in the support area.

Open Ticket AI – AI for Ticket Classification & Automation

Automate ticket assignment (queue, priority, language), generate summaries, and create synthetic training data on demand – integrable with OTOBO, Znuny, and Zammad. More information, demos, and API can be found here: https://open-ticket-ai.com

Conclusion

For IT administrators and helpdesk teams in small to medium-sized businesses, open-source ticketing systems offer a cost-effective and customizable alternative to proprietary solutions. Whether you choose an OTRS successor with a familiar concept (like OTOBO or Znuny) or opt for modern UI and multi-channel communication with Zammad – the decision depends on your specific requirements.

OTOBO appeals to users seeking maximum functionality and an active German community, as well as an easier entry through Docker support. Znuny is ideal for long-time OTRS users and organizations that value stability, support, and continuous updates. Zammad, on the other hand, targets teams that prioritize usability, real-time updates, and AI-powered productivity.

Ultimately, these are free ticketing systems that still meet professional standards. Through their open-source licenses (GPL/AGPL), you benefit from transparency, community-driven innovation, and the freedom to extend the system yourself if needed. The investment in such a system – whether personal (knowledge building) or infrastructural – pays off in the form of more efficient support processes and satisfied end-users.

When implementing, it is worthwhile to utilize the documentation and community resources – such as the OTOBO Documentation for OTOBO/Znuny or the Zammad guide and forums. This ensures that the chosen open-source ticketing system is optimally tailored to your own needs and represents a sustainable solution for the helpdesk in the long term.