Introduction
If there is one product that best represents the ticketing system space, it is Zendesk, much like Salesforce in the CRM world.
Founded in 2007, Zendesk shaped the modern customer support ticketing model for many years, introducing capabilities such as email-to-ticket conversion, multi-channel support, SLA management, knowledge bases, and team collaboration.
As we move into 2026, however, enterprise expectations for ticketing systems are clearly shifting.
On one side, Zendesk, as a commercial SaaS platform, is increasingly constrained by cost, limited deep customization, and concerns around data ownership.
On the other side, AI is redefining what a ticketing system can be. Companies are no longer satisfied with simple auto-replies. They expect AI to work with real data under proper permission controls, reference historical cases, and trigger workflow actions, pushing support operations toward true automation.
In this article, we review some of the most notable open-source alternatives to Zendesk. These include long-established and proven projects such as Zammad and osTicket, as well as newer solutions like NocoBase that place stronger emphasis on extensibility and automation, and are already starting to integrate AI into real scenarios.
Whether you want a fast replacement for Zendesk or are looking to build a foundation for AI-driven support workflows, the comparisons below should help you find the right direction.
💬 Hey, you're reading the NocoBase blog. NocoBase is the most extensible AI-powered no-code/low-code development platform for building enterprise applications, internal tools, and all kinds of systems. It’s fully self-hosted, plugin-based, and developer-friendly. → Explore NocoBase on GitHub
Open-source Zendesk Alternatives
A capable open-source alternative to Zendesk should be able to answer several key questions:
- Is the ticketing system mature enough to handle everyday customer support?
- Does it provide a knowledge base, automation rules, and a solid permission model?
- Can it be extended and integrated as business needs evolve?
- With AI becoming more important, does it have room to grow into a more intelligent system?
The following open-source solutions are evaluated in this article:
- NocoBase: An AI-ready ticketing foundation for business systems, allowing AI to operate within real data and workflows
- Zammad: A mature and full-featured open-source help desk, widely regarded as a direct Zendesk alternative
- FreeScout: A lightweight shared inbox ticketing tool, ideal for small and medium-sized teams that need quick deployment
- osTicket: A classic open-source ticketing system covering core support workflows, stable but more traditional in design
- GLPI: A ticketing and asset management platform focused on internal enterprise IT service management (ITSM)
If your goal is simply to find a mature, ready-to-use open-source replacement for Zendesk, Zammad is a strong choice. If you are aiming to build a system-level platform that deeply integrates with business processes and prepares your support workflows for AI, NocoBase is well worth closer examination.
Next, we will take a closer look at each open-source alternative in detail.
NocoBase
Official website: https://www.nocobase.com/
GitHub: https://github.com/nocobase/nocobase
GitHub Stars: 21.4k
Online demo: AI-Powered Intelligent Ticketing System
NocoBase is an open-source, self-hosted, AI-powered no-code and low-code development platform. Built on a data-model-driven foundation with a plugin-based architecture, it allows teams to rapidly build and iterate enterprise business systems. Beyond CRM and project management, NocoBase can also be used to create highly extensible intelligent ticketing systems.
The NocoBase ticketing system covers the entire support lifecycle, from request intake and automated assignment to SLA management and knowledge accumulation.
Unlike traditional help desk products, NocoBase treats the ticketing system as part of a broader data model. You start by defining the underlying business structure, such as customers, service levels, assets, and process stages, and then layer pages, permissions, and automation rules on top.
As a result, the ticketing system is not a fixed template, but a system that evolves continuously with the business:
- Tickets can be connected with CRM, project management, or internal approval workflows
- Different teams can be assigned different data permissions and processing views
- AI employees can be embedded into workflows to perform classification, retrieval, and reply suggestions based on real business data
This level of system-wide extensibility is what most clearly differentiates NocoBase from other open-source Zendesk alternatives.
Email-to-ticket
NocoBase supports unified ticket intake from multiple sources, including:
- Public forms
- Customer portals
- Email parsing and email-to-ticket conversion
- API and webhook integrations
Requests from all channels are automatically deduplicated and routed into a single ticket entry point, fully covering common email-to-ticket use cases.
Email-based ticketing in NocoBase can also work together with AI employees. For example, once an email conversation is completed, you can invoke the AI employee Dex to summarize the conversation and automatically fill key information into the ticket form. With a single click, a structured ticket is created, without manual copying, pasting, or repeated data entry.
Knowledge base
The NocoBase ticketing system includes built-in mechanisms for continuous knowledge accumulation:
- Ticket resolution processes can be automatically converted into knowledge articles
- When new tickets are created, similar solutions can be recommended based on existing knowledge
- AI employees can help search the knowledge base and generate suggested replies
This allows the ticketing system to handle requests while gradually forming a self-reinforcing knowledge loop.
Automation and SLA
NocoBase provides comprehensive automation and SLA management:
- Define response and resolution targets for different priority levels, such as P0 to P3
- Automatically track response times, resolution times, timeout alerts, and escalation rules
- Enable automated workflow transitions and rule-based triggers
In intelligent ticketing workflows, SLAs are embedded throughout the entire lifecycle rather than treated as static attributes.
RBAC
As an enterprise application development platform, NocoBase includes a robust role-based access control (RBAC) model, which is fully inherited by the ticketing system:
- Access control based on user roles and data scope
- Role-specific permissions and views
- Support for row-level and field-level access control
- AI employees are also governed by RBAC rules
This permission model is well suited for enterprise service desks and multi-team collaboration.
Extensibility and integration
NocoBase is designed for system-level extensibility, not just incremental customization.
It provides open APIs, SSO, webhooks, and HTTP request nodes within workflows, making it easy to integrate with external systems such as CRM platforms, asset management tools, and alerting services.
At the same time, its plugin system allows continuous extension on both the server side and the UI, including custom blocks, fields, and business actions. This ensures the ticketing system can grow with business needs instead of being locked into predefined templates.
On the frontend, more flexible page layouts can be implemented using JS blocks. These blocks can be generated and configured directly by AI employees. You simply describe the desired outcome, and the AI produces usable UI components.
Crucially, these blocks are not isolated scripts. They operate within the same data model and permission framework as the rest of the system, and can interact with ticket fields, workflow states, and other page components. This allows both the interface and business logic to evolve continuously as requirements change.
AI capabilities
Across all of these dimensions, AI capabilities are embedded throughout the NocoBase ticketing system. From structuring information during email-to-ticket conversion, to knowledge retrieval and reply suggestions, to automated classification and assignment within workflows, AI employees act as an integral part of the system.
In many traditional ticketing systems, AI is usually limited to chatbots or response generation and is often applied only at the final step of ticket handling, helping agents reply faster.
In NocoBase, AI employees can be applied far more broadly and can be customized to work closely with your own business systems.
Zammad
Official website: https://zammad.com/
GitHub: https://github.com/zammad/zammad
GitHub Stars: 5.3k
Zammad is a well-established open-source ticketing and customer support system released in 2016. It can be deployed on self-hosted servers or via Docker, offering a unified ticket entry point that consolidates requests from email, chat, phone, and social channels. Licensed under AGPL-3.0, Zammad focuses on transparency, flexibility, and long-term maintainability as a help desk solution.
Email-to-ticket
Zammad provides native support for email-to-ticket workflows, automatically converting customer requests from email and other channels, such as chat, into structured tickets. This allows support teams to process large volumes of incoming requests without manual data entry.
Knowledge base
Zammad includes a built-in knowledge base and reusable text modules, enabling teams to create FAQs, standard reply templates, and searchable help content. Both agents and end users can access the knowledge base to find relevant information, helping reduce duplicate ticket submissions.
Automation and SLA
Zammad offers built-in SLA management, allowing teams to define response and resolution targets for different request types. Administrators can set first response times, update response times, and final resolution deadlines based on ticket category, customer group, or priority. The system tracks ticket progress against these targets, applies escalation rules, and calculates SLAs based on business hours. Notifications are triggered as deadlines approach or are exceeded, helping teams meet their service commitments.
RBAC
Zammad’s access control model is based on roles and ticket groups. Roles represent collections of permissions, and in addition to predefined roles such as admin, agent, and customer, custom roles can be created with tailored permission sets.
At the ticket level, group access levels determine what agents can see and do within specific groups, for example read-only access, editing, creation, or assignment. Roles can also include group-specific permissions, making access boundaries between teams and ticket groups clear and manageable.
Extensibility and integration
Zammad exposes a full REST API for integration with other business systems and automation services. Webhooks allow ticket events to be pushed to third-party platforms in real time, enabling cross-system workflows. It also supports enterprise authentication integrations, including LDAP, Active Directory, and single sign-on via SAML or OpenID Connect, keeping access control aligned with existing identity systems.
Built-in integrations, such as linking GitHub or GitLab issues, further support collaboration between support and development teams by surfacing code-related issues directly within the help desk.
AI capabilities
Zammad does not natively include AI agents or intelligent ticket execution features. AI-related functionality is typically achieved through external integrations, such as connecting to LLM services or automation tools.
At its current stage, Zammad does not embed an AI runtime in its core architecture. While it can be extended through APIs to work with external intelligent services, this requires additional setup and development effort.
FreeScout
Official website: https://freescout.net/
GitHub: https://github.com/freescout-helpdesk/freescout
GitHub Stars: 4k
FreeScout is a lightweight open-source help desk positioned as an open-source alternative to Help Scout. Its primary goal is to deliver a low-cost, self-hosted shared inbox ticketing system, making it a good fit for small and medium-sized teams that rely mainly on email-based support.
Rather than focusing on complex workflows or enterprise-level SLA management, FreeScout prioritizes simplicity, quick setup, and easy maintenance of core support processes.
Email-to-ticket
Email handling is one of FreeScout’s core strengths:
- Automatically pulls emails from one or multiple mailboxes
- Converts incoming emails into assignable support tickets
- Keeps email replies and ticket conversations fully synchronized
For teams whose support workflows are primarily driven by email, this functionality is stable, straightforward, and easy to operate.
Knowledge base
FreeScout includes a basic knowledge base module for publishing FAQs, standard responses, and help articles. Compared with more feature-rich help desk platforms, its content management is intentionally simple:
- Supports basic titles and content categorization
- Allows customers to search and browse common questions
It works well as a centralized FAQ repository, but is not designed for complex or highly structured knowledge management.
Automation and SLA
FreeScout offers entry-level automation features:
- Simple rule-based triggers, such as conditional assignment and automated reply templates
- Optional modules to extend automation capabilities
However, it does not provide the fine-grained SLA controls, complex conditions, or multi-step workflows found in enterprise ticketing systems. More advanced automation typically requires plugins or integration with external automation tools.
RBAC
FreeScout includes basic role-based permission management to control what users can see and do in the system.
By default, it distinguishes between administrators and regular users. Administrators can assign specific permissions to individual users through the “Settings → Permissions” interface.
Extensibility and integration
FreeScout’s extensibility is centered around its official module system. Teams can enable modules as needed, such as team collaboration, customer portals, automation rules, SSO authentication, or Telegram notifications. This modular design helps keep the system lightweight while allowing teams to selectively add functionality as their support needs grow.
AI capabilities
FreeScout does not provide built-in AI functionality and is not natively designed for AI-driven workflows.
That said, because it is open source, it can be integrated with third-party AI services through APIs or custom extensions, which may be sufficient for basic intelligent assistance scenarios.
osTicket
Official website: https://osticket.com/
GitHub: https://github.com/osTicket/osTicket
GitHub Stars: 3.6k
osTicket is a long-standing open-source ticketing system built around simplicity, stability, and low maintenance overhead. Its goal is to satisfy essential support requirements with as little complexity as possible. Requests from email, forms, and web portals are converted into structured tickets and handled through queues, assignments, and status-based workflows.
At a functional level, osTicket provides the core capabilities most support teams need:
- Email-based ticket intake that automatically turns incoming messages into tickets
- Queue and workflow management with multiple queues, statuses, and assignment options
- A basic knowledge base for FAQs and standard response templates
- A simple permission model with administrator, agent, and guest roles
- Limited plugin and integration support, with a smaller ecosystem than modern extensible platforms
From a user experience perspective, osTicket follows a clear “function over form” approach. It does not offer the polished or highly configurable interfaces seen in newer products, but its stable, well-understood workflows, refined through years of community use, continue to make it a reliable choice for many teams.
However, osTicket does not include any native AI functionality and does not support intelligent replies, automatic classification, or context-aware assistance.
In addition to customer support ticketing systems, the open-source ecosystem also includes projects aimed at other ticketing use cases, such as internal IT service management.
GLPI
Official website: https://glpi-project.org/
GitHub: https://github.com/glpi-project/glpi
GitHub Stars: 5.5k
GLPI is primarily designed for internal enterprise IT service management (ITSM), supporting scenarios such as hardware repairs, access requests, and day-to-day operations and maintenance support.
Conclusion
There is no shortage of open-source alternatives to Zendesk, but they broadly fall into two categories.
The first includes mature open-source help desk systems such as Zammad, osTicket, and FreeScout. These tools typically cover email-to-ticket workflows, knowledge bases, SLA management, and basic access control, making them a good fit for teams that want to reduce SaaS costs and adopt a self-hosted solution with minimal friction.
The second category represents a shift in how ticketing systems are defined. Instead of being limited to customer support, ticketing becomes part of broader business workflows and increasingly AI-driven. New-generation platforms like NocoBase place tickets within a unified framework of data models, permissions, workflows, and AI employees. In this context, AI does more than generate responses. It actively participates in classification, retrieval, workflow progression, and even system configuration.
If your goal is simply to replace Zendesk, a mature open-source help desk may be sufficient. If, however, you want your ticketing system to integrate deeply with business processes and evolve into the foundation of AI-powered support workflows, NocoBase offers stronger long-term value.
❤️ Thank you for reading through to the end. If you found this article valuable, feel free to share it with others.
Related reading:
- 4 Open Source Data Management Tools for Business Systems
- 4 Lightweight Enterprise Software for Business Processes (With Real-World Cases)
- 6 Enterprise Softwares to Replace Excel for Internal Operations
- 10 Open Source Tools Developers Use to Reduce Repetitive CRUD
- Top 12 Open-source AI Workflows Projects with the Most GitHub Stars
- 6 Open-Source No-Code & Low-Code Tools for Software Agencies
- Top 10 Open-source AI CRM Projects with the Most GitHub Stars
- How to Quickly Build a Real System to Replace Excel: A Complete Guide
- Top 5 Open-Source AI Internal Tools on GitHub
Top comments (0)