Kimai

Last reviewed Sep 13, 2026 · 862 words

Kimai is the only time tracker in our catalogue I would hand to an accountant. Customers, projects and activities carry their own hourly rates, timesheets round by rule, and the invoice module turns a month of entries into a numbered PDF or DOCX from a template you control, with the paid-and-unpaid state tracked inside the same app. That combination is why agencies, lawyers and freelancers who bill by the hour run it, and why it has survived since 2006. It is also more app than a person who wants to know "how long did I spend on the garden this week" needs; for them, the lighter tools at the end of this guide are kinder.

It needs MySQL or MariaDB, and 512 MB is realistic

Kimai 2 is a PHP Symfony application, and the current major line requires MySQL or MariaDB; SQLite was dropped and is not coming back. The official Docker image (kimai/kimai2, in apache and fpm flavours) plus a MySQL container is the whole stack:

services:
  kimai:
    image: kimai/kimai2:apache
    environment:
      - DATABASE_URL=mysql://kimai:kimaipass@db/kimai?charset=utf8mb4&serverVersion=8.3.0
      - TRUSTED_HOSTS=time.example.com,localhost
      - [email protected]
      - ADMINPASS=changeme-on-first-login
    ports:
      - "8001:8001"
    volumes:
      - ./kimai-data:/opt/kimai/var/data
      - ./kimai-plugins:/opt/kimai/var/plugins
  db:
    image: mysql:8.3
    environment:
      - MYSQL_DATABASE=kimai
      - MYSQL_USER=kimai
      - MYSQL_PASSWORD=kimaipass
      - MYSQL_ROOT_PASSWORD=rootpass
    volumes:
      - ./db:/var/lib/mysql

The 512 MB figure in our catalogue holds for a team of 10; a single freelancer runs it comfortably alongside other services. TRUSTED_HOSTS must match the hostname you visit, and forgetting it produces a blank 400 page that has confused every first-time installer I know. Setting it on day one is the single most useful thing to take from this guide if you are about to deploy.

The data model is Customer > Project > Activity, and it is worth respecting

Every timesheet entry belongs to an activity, which belongs to a project, which belongs to a customer. Rates cascade down that chain and can be overridden at each level, and per-user rates layer on top. Budgets (in hours or money) sit on projects and activities with warning thresholds. If you set this up carelessly, with a project called "Misc" and an activity called "Work", none of the reporting means anything. If you spend 30 minutes modelling how you actually bill, the weekly report, the customer statement and the invoice all fall out without further effort. Time entries can be started with a live timer or entered after the fact; team leads can approve or lock periods so that invoiced hours cannot be edited later.

Invoicing is built in, and templates are files you edit

The invoice module filters entries by customer and date range, applies rates, and renders through a template: HTML, DOCX, XLSX, ODS or CSV, with PDF export from the HTML variant. Templates live in a directory and are ordinary files, so a designer can match your letterhead in Word without touching PHP. Invoice numbers follow a configurable pattern, and the generated documents are archived in Kimai with a status flow of new, pending, paid and cancelled. It is not accounting software (no ledger, no tax filing, no recurring billing), and for full accounts receivable you would pair it with Invoice Ninja or export to your bookkeeping package. For a freelancer sending 10 invoices a month it is entirely sufficient on its own.

The plugin marketplace is partly commercial

Kimai's core is AGPL-3.0 and complete, but a marketplace of plugins extends it, and a good number of the most-wanted ones (expenses, custom fields, task tracking, some report formats) are sold by the maintainer for a one-off fee in the tens of euros each. That is how the project is funded, and I think it is a fair model, but budget for it if your requirements list includes "track expenses against projects". Free plugins cover LDAP and SAML login, which the core also supports, plus API-driven integrations. The REST API is complete enough that community mobile apps and browser extensions exist for starting and stopping timers.

Lighter alternatives for lighter needs

TimeTagger is a single-user, tag-based tracker that runs on a fraction of the resources and has no invoicing; it suits a developer tracking their own week. Traggo is similar in spirit with tags instead of hierarchy and a clean dashboard. Solidtime is the newer team-oriented option with a modern UI and less reporting depth. If the word "invoice" does not appear in your requirements, one of those three will get you tracking in 10 minutes with less to configure.

What I'd do

For anyone who bills hours to more than one client, Kimai behind Caddy with MySQL, TRUSTED_HOSTS set before the first visit, nightly database dumps, and 30 minutes spent building the customer and project tree properly before entering a single hour. Buy the expenses plugin if you incur costs on client work. For a solo developer or a household, install TimeTagger instead and keep Kimai for the day you start invoicing.