Developer per site (php5, mysql)

I am looking for a php developer to maintain/maintain an existing internet magician.

The store is old, self-written, php5/mysql. You can consider an adaptation to work with php7.

Piecework, according to tasks. For example:
- improvement of existing integrations with carriers
- development of integration with Yandex.Market (interface implementation)
- implementation of printing plates (generation of an invoice for the order)
and the like.

There are plans to develop a new online store. But before you hit the long development of a new store - you need to perform a number of tasks for the existing one, which would enable the business to continue comfortable work and perform its tasks.