We have been using KIMAI for many years, previously self-hosted at an internet provider, and for some time now in the cloud. The data model fits our business field perfectly, in which we bill certain projects based on effort and others at a fixed price (budgeted). Both billing models are supported by KIMAI. For budgeted projects, we keep track of the respective consumption of time and costs in relation to the budget (burndown). For time-and-materials projects, we export all billable hours along with the stored hourly rates monthly or quarterly as a basis for the invoices, which we create with another invoicing/accounting software.
In addition to what I consider a very practical data model and the logical structure, the cloud solution is also very well designed in terms of look and feel, modern and intuitive to use. I find everything where I expect it to be. Numerous small features, such as hiding columns or the filter options, make work easier. In addition, a great deal is configurable, so I am not forced to adapt my processes to KIMAI; instead, I can adapt KIMAI to my needs.
Support responds very quickly. I have also been able to submit several suggestions that were actually implemented promptly. I have not yet experienced such implementation strength with any other provider of cloud solutions.
Out of conviction and free of charge, I have shown KIMAI to befriended business partners from completely different industries, recommended it to them, and supported them in setting it up.
From my point of view, an absolute recommendation, very professional and well thought out. You can tell from the software its maturity and from the manufacturer the experience in this field.