TYPO3 Developer

The client is looking for a developer to support their internal dev team in maintaining and further developing a long-running TYPO3 app (v6.2) for a customer.
The freelancer should be willing to work with the client for a longer period (min. 3 months). Since there is not one big chunk of work to be done, but rather new features and bugfixes every now and then, the client wants to agree on a minimum number of days per month (e.g. 5 days per month) that the freelancer is available. It might be a few more days in one month but the minimum number is always guaranteed.
Remote work from Berlin with the occasional trip to the client's office in Hamburg is no problem.