we are web engineers

based in Cogolin, France.

Contact us


Behind the company

Mistralys is specialized in web development

Hello, my name is Sebastian Mordziol. I created Mistralys in 2005, but my web expertise dates back to when dial-up modems were a thing. I started out as a graphics designer, and quickly realized that I wanted more: I longed to make my designs work. From there, I slipped into website development, which ultimately led to my real calling.

With my company Mistralys, I have focused on building highly specialized application suites for my customers. We thrive in developing tools for which no mainstream software exists. We analyze the workflows and needs of the people who will be working with the tools, and build interfaces that they can use on a daily basis. One of our core principles is to make software that documents itself, with meaningful context extracted from our experiences with the end user's workflows.


Years experience



What we can do

Case studies

Some solutions we devised

A modular product database

1&1 needed a way to bring together their diversified range of products in one central database. It had to be flexible enough to handle information for products like dedicated servers and mobile phones. The resulting intranet tool that Mistralys designed and developed takes a modular approach: It allows freely defining the structural blueprint of each type of product. These blueprints then translate to the editing masks that product managers use to enter product information.

One of the core functions of the tool is the feature tables editor: This is where the structure of the product feature overviews are built as they are shown in the 1&1 stores.

All data in the tool is stored in a versioning and campaigning system. The campaigning system allows for the parallel deployment of product changes for marketing campaigns. Several API endpoints allow client systems within the 1&1 network to access the product information. Custom tailored export APIs enable the consumption of data in highly specialized ways, separately for every campaign.

The development took several years, split into several feature-set based milestones, and is still ongoing today.

  • Customer:1&1 Internet AG
  • Name:SPIN
  • Type:Intranet Application
  • Start year:2013
  • Technology:PHP, Web UI

Some statistics

Authoring system for customer communications

IONOS sends out a considerable amount of customer communications over the 8 markets they are present in. This includes e-mailings, SMS, push notifications, and traditional paper mail. These types of communication were all handled separately, and often by different teams. The goal was to unify the creation and editing of all communications into a single application.

When we started this project, the first and biggest milestone was to enable the authoring of e-mailings. These were still being built by a web agency, driving costs up. It was the perfect occasion to bring our own experience with e-mailings into play: We had already developed a specialized HTML email generation framework in-house. It is called Rygnarôk, and we use it to build e-mailings for our customers.

The application we created uses our framework as HTML generation backend. The mailing teams can edit their e-mailings in a dynamic builder interface, without needing any knowledge of HTML templating. The plain text version is generated automatically from the same sources. The tool interfaces directly with the IONOS network-internal services. Using a versioning and publishing system, e-mailings can be registered in the send system.

This first milestone brings all e-mailing aspects together for a streamlined workflow. Development is still ongoing to bring the resting communication types into the fold.

  • Customer:IONOS
  • Name:Communication Center
  • Type:Intranet Application
  • Start year:2015
  • Technology:PHP, Web UI

Some statistics

Open source

GitHub-based projects

PHP, Composer

Application utils

A developer's toolset

Collection of legacy tools, modernized and ported to a separate project.

View on GitHub

PHP, Composer

DeepL XML translator

Automated translations

Allows translating large sets of texts using DeepL's XML translation service.

View on GitHub


CKEditor paste plaintext

WYSIWYG Editor plugin

Small plugin that adds a "Paste as plain text" toggle button to avoid pasting any markup.

View on GitHub

PHP, Composer

Errorcode incrementor

Development tool

Webservice or Composer dependency to manage counters, like error code counters.

View on GitHub

PHP, Composer

Text diff

UI Helper

Used to display differences visually between texts.

View on GitHub

PHP, Composer

Subset sum

Development tool

Calculates the subset sum of a range of numbers to match a target number.

View on GitHub

PHP, Composer

Application localization

Translation tools

Application translation layer with an integrated UI, for backend and frontend.

View on GitHub

PHP, Apache Velocity, Composer


Preprocessor language

Specialized language used for preprocessor commands in an emailing application.

View on GitHub


WordPress SQL domain replacer

WordPress migration helper

Script used to replace the site domain in a WordPress SQL dump when moving to a new domain.

View on GitHub

PHP, Composer

Version string parser

Development tool

Retrieve the major, minor and patch version numbers of application version strings.

View on GitHub

PHP, Composer

Column widths calculator

Development tool

Calculates widths given a flexible amount of inputs.

View on GitHub


Get in Touch


C30 Quai de la Galiote
Les Marines de Cogolin
FR-83310 Cogolin

+33 786 995 353