Time Tracker

There are hundreds of time trackers out there. Most of them look the same, work the same, and cost the same — a monthly fee per user that quietly adds up until someone in accounting starts asking questions. Kimai takes a different approach: it’s open source, it’s free to self-host, and it’s been around since 2006. That’s not a typo — nearly two decades of development, long before “SaaS time tracker” became a crowded category.

What a time tracker actually needs to do

Strip away the marketing buzzwords and a time tracker has one job: record how people spend their working hours. Everything else — reports, invoices, integrations — is built on top of that foundation.

The trouble is, most time trackers optimize for the demo, not for daily use. Flashy dashboards look great in a sales call but slow you down at 8 AM on a Monday. Kimai takes the opposite approach: the most common action (starting and stopping a timer) is one click. Everything else stays out of your way until you need it.

Who uses an open-source time tracker?

Agencies billing by the hour need every minute assigned to the right client. Kimai tracks time against a hierarchy of customers, projects, and activities. At the end of the month, invoices generate from actual recorded hours — no guessing, no rounding, no spreadsheets.

Development teams use Kimai to understand where engineering time goes. When half the sprint disappears into unplanned support work, the time tracker makes that visible. You can’t fix what you can’t measure.

Universities and research institutions appreciate two things about Kimai: it’s free, and it runs on their own servers. Research budgets are tight, data protection requirements are strict, and a self-hosted open-source time tracker checks both boxes.

Trades and construction firms need a time tracker that works on a job site. Kimai runs in any browser — including the one on that dusty tablet in the foreman’s truck. The kiosk mode lets workers clock in and out with a PIN, no individual accounts required.

Freelancers want something lightweight but professional. Kimai delivers clean time reports for clients and a solid paper trail for taxes. No per-user fees when you’re the only user.

Why open source matters for time tracking

A time tracker sees everything: when your team starts working, how long they spend on each task, when they take breaks. That’s sensitive data. With a proprietary SaaS tool, you trust the vendor’s privacy policy and hope for the best. With Kimai, you can read every line of code, host it on your own infrastructure, and know exactly where your data lives.

Open source also means no artificial limitations. There’s no “starter plan” with 5 users and crippled reporting, no “enterprise tier” that unlocks the features you actually need. Self-hosted Kimai gives you everything, for free, with unlimited users.

Extending Kimai: plugins, API, and custom fields

Out of the box, Kimai covers the fundamentals well. But businesses have specific needs, and that’s where the plugin system comes in. Pre-built plugins add features like advanced invoicing, custom reports, approval workflows, and expense tracking. If none of the existing plugins fit, the API lets you build your own integrations.

Custom fields deserve a special mention: you can add any data field to time entries, projects, customers, or users. Tracking cost centers? Add a custom field. Need a purchase order number on every entry? Custom field. This flexibility means Kimai adapts to your processes instead of forcing you to adapt to its assumptions.

Cloud or self-hosted — same software, your call

The Kimai Cloud is the fastest way to get started: sign up, create your instance, invite your team. It runs on European servers, handles updates and backups automatically, and includes all commercial plugins.

Self-hosting gives you full control. Run Kimai on your own Linux server, your company’s Kubernetes cluster, or a five-dollar VPS — it’s your choice. Docker images make deployment straightforward.

Both versions run the same code. Switching directions is always possible: cloud customers receive full data exports, self-hosted users can migrate to the cloud. No lock-in, no data hostage situations.

Give Kimai a try and discover what time tracking feels like when the software works for you, not the other way around.