Kimai

What Is Kimai?

Every freelancer or agency that has tracked time with a commercial SaaS tool has had the same sinking feeling: the monthly bill quietly climbing as the team grows, the data locked behind someone else's API, and the nagging awareness that your hours — the raw material of your invoicing — live on servers you do not control, in a jurisdiction you did not choose.

Kimai exists because a German developer decided that problem was solvable. Originally launched in 2006 and completely rewritten as Kimai 2 on the Symfony PHP framework, Kimai is an open-source time tracking application that you can self-host on your own infrastructure. It gives freelancers, agencies, and teams multi-user time tracking, project management, invoicing, and reporting with no licence fees and complete data sovereignty.

The trade-off is real: Kimai demands more from you than Toggl or Harvest. You need a server. You need to maintain it. The interface is functional rather than beautiful. But for teams that value data ownership over convenience — particularly those operating under GDPR obligations — Kimai offers something commercial tools structurally cannot: your time data on your servers, under your rules, at no recurring cost.

Maintained by a solo developer based in Munich, Kimai has quietly built a user base spanning thousands of companies, universities, and freelancers across Europe. It is not the prettiest time tracker. It is the one that lets you own everything.

Key Features

Multi-User Time Tracking

Kimai supports start/stop timers, manual time entry, and calendar-based weekly timesheets. Each user can track time against projects and activities, with configurable permissions controlling who can see and edit what. Team leads can view timesheets across their team, approve entries, and manage workloads. The timer interface is straightforward — select a project, select an activity, and start the clock. It lacks the micro-interaction polish of Toggl's one-click timer, but it covers the core workflow without unnecessary complexity.

Project and Customer Management

Every time entry in Kimai is linked to a customer, project, and activity hierarchy. You define customers with contact details, create projects under each customer, and define activities within projects. This three-level structure works well for agencies managing multiple clients with overlapping project types. Custom fields extend the data model for specific needs, such as billing rates, contract numbers, or internal codes.

Invoicing

Kimai generates invoices directly from tracked time entries, outputting PDF, DOCX, or HTML documents from customisable templates. You select a date range, a customer, and filter by project — Kimai calculates totals and produces a ready-to-send invoice. For freelancers who currently copy data from a time tracker into a spreadsheet and then into an invoice template, this feature alone justifies the setup effort. Template customisation requires some familiarity with Twig syntax, which is a hurdle for non-developers but offers significant flexibility.

Plugin Marketplace

Kimai's plugin system extends the core platform with over 50 extensions. Premium plugins — available as affordable one-time purchases typically ranging from EUR 15 to EUR 79 — add features like audit trails, custom fields, task management, expense tracking, and advanced reporting. The one-time pricing model is notable: you pay once and receive updates, rather than adding monthly subscription costs. The audit trail plugin is particularly valuable for regulated environments that need immutable records of time entry changes.

Kiosk Mode and API

For environments where employees clock in and out at a shared terminal, Kimai offers a kiosk mode that simplifies the interface to a badge-scanning or PIN-entry flow. The REST API enables custom integrations with project management tools, accounting software, or internal dashboards. LDAP and SAML SSO support connects Kimai to existing identity infrastructure, making it viable for larger organisations with centralised user management.

Pricing

Kimai's pricing model is its most compelling feature for cost-conscious teams. The self-hosted version is completely free under the MIT licence, with no user limits, no feature restrictions, and no artificial caps. You download it, install it on your server, and use it indefinitely. The only cost is your hosting infrastructure.

Premium plugins are priced as one-time purchases, typically between EUR 15 and EUR 79 each. The audit trail, custom fields, and task management plugins are the most popular. This model means a fully featured Kimai installation with several premium plugins costs less than a single month of Harvest for a medium-sized team.

Kimai Cloud, the managed hosting option, starts at approximately EUR 9 per month. It removes the self-hosting burden with automatic updates, daily backups, and EU-hosted infrastructure. However, the cloud version has historically lagged behind the self-hosted version in feature availability, and power users tend to prefer self-hosting for maximum control.

For a ten-person agency, the total cost of ownership with self-hosting might be EUR 5-15 per month in server costs plus a few one-time plugin purchases. The equivalent annual cost on Harvest would be several hundred euros. The savings are substantial, but they come at the cost of your time managing the infrastructure.

EU Compliance & Privacy

Kimai's GDPR story is structurally different from most SaaS tools: when self-hosted, there is no third-party data processor. Your time data stays on your servers, in your data centre, under your jurisdiction. There is no Data Processing Agreement to negotiate because you are both the controller and the processor.

The platform includes configurable data retention policies, data export capabilities for subject access requests, and an audit trail plugin for compliance logging. Multi-language support covers 30+ languages, reflecting Kimai's broad European user base.

For organisations in regulated sectors — public bodies, healthcare, legal services — this self-hosted model eliminates an entire category of compliance risk. You do not need to evaluate a vendor's sub-processors, review their security certifications, or worry about transatlantic data transfers. The data simply never leaves your infrastructure.

Kimai Cloud, for those who prefer managed hosting, runs on EU-hosted infrastructure in Germany, providing a GDPR-compliant alternative for teams that cannot manage their own servers.

Who It's Best For

Freelancers and small agencies who want professional time tracking and invoicing without monthly subscription fees and are comfortable with basic server administration.

European organisations with strict data sovereignty requirements — public sector bodies, law firms, consultancies — where time tracking data must remain on controlled infrastructure.

Cost-conscious teams who need multi-user time tracking with project management but cannot justify the per-user pricing of commercial alternatives like Harvest or Clockify's paid tiers.

Technical teams who value open-source transparency and want to extend their time tracking with custom plugins and API integrations.

The Verdict

Kimai is not the easiest time tracker to set up, and it will never win a design award. What it offers instead is genuine ownership: of your data, of your costs, and of your workflow. For teams willing to invest the initial setup effort, the return is a powerful, extensible time tracking platform that costs virtually nothing to run and keeps every hour you track exactly where it belongs — on your own servers. It scores 7.3 overall, with standout marks for value (9.0) and EU compliance (9.5), held back by a dated UI and limited support bandwidth.

Frequently Asked Questions

Is Kimai suitable for non-technical teams?

Day-to-day use of Kimai requires no technical skills — the web interface is intuitive for time entry, reporting, and invoicing. However, the initial installation on a self-hosted server requires familiarity with Linux, PHP, and database administration. Teams without technical resources should consider Kimai Cloud, which eliminates the server management requirement entirely.

How does Kimai compare to Toggl Track?

Toggl offers a more polished interface, better mobile apps, and a smoother onboarding experience. Kimai counters with self-hosting for data sovereignty, free unlimited users, built-in invoicing, and one-time plugin pricing. Toggl is better for teams that prioritise ease of use; Kimai is better for teams that prioritise data control and cost.

Can Kimai handle invoicing for multiple clients?

Yes. Kimai's customer-project-activity hierarchy supports managing multiple clients with different billing rates. You can generate invoices per customer, per project, or per date range. Customisable invoice templates allow you to match your branding and include the specific line items your clients expect.

What happens if the developer stops maintaining Kimai?

Kimai is open-source under the MIT licence, meaning the source code is freely available and can be forked by anyone. The plugin marketplace and active GitHub community provide a degree of resilience. However, the project's dependence on a single core developer is a legitimate risk — it is worth monitoring the project's activity before committing to a large-scale deployment.

Does Kimai integrate with accounting software?

Kimai has no native integrations with accounting platforms like DATEV or Xero. However, its REST API and CSV/Excel export capabilities allow you to build custom data pipelines. Several community plugins provide export formats compatible with common accounting workflows, and the invoice generation feature can produce documents suitable for direct submission to clients.