Querydsl commercial offers

We are frequently asked about our future plans regarding Querydsl and in which direction we intend to take it commercially. With the recent announcements of the jOOQ project to change its licensing model from a pure OSS licensing model to dual licensing our users are wondering if we might follow suit.

We have no intention of changing the licensing model of Querydsl and will keep on using a pure open source license for the foreseeable future. We feel that middleware should be transparent, and open source is one of the best models to guarantee both transparency and an interactive development model.

Our commercial model for Querydsl is open source software and commercial services. Querydsl is free to use and you will get free public support for it, but for private support, bigger additions and closed source extensions we are available for consulting and development at reasonable hourly rates.


Querydsl training is available in packages and can also be customized for special needs. The available packages are


one day of training to get an overview of the general functionality of Querydsl and usage examples for its most popular modules JPA and SQL

Querydsl & JPA/Hibernate

two days of training to get an overview of Querydsl and how it is best used with JPA including best practices for service/DAO design with Querydsl

Querydsl & SQL

two days of training to get a general overview of Querydsl and how it is best used with JDBC/SQL

Project development

Development services for projects involving Querydsl and related technologies are also available. We have worked with small startups and big global corporations to provide solutions using open source Java and Web technologies.

See our references for some examples of projects we’ve done in the past.

In addition, we have consulted a major Finnish software company on Hibernate performance problems. And later given training on Hibernate and Querydsl usage for their development team in St. Petersburg.


Querydsl extensions in both open source and closed source form can be provided by us via development projects.

Examples of such extensions are
  • support for SQL/NoSQL technologies that are not yet supported by Querydsl (e.g. DB2 or Cassandra)
  • higher level abstractions for Querydsl that fit into your IT infrastructure
  • integration of Querydsl into other middleware frameworks or libraries

Contact us at querydsl@mysema.com if any of these options sound attractive to you. And if you haven’t yet participated in the Querydsl user survey, please do so.


HelMet integration for Linked Events

The most recent addition to Linked Events, the event information aggregator developed by Mysema, is the integration of events taking place at libraries throughout the Helsinki region. This information is kindly provided by HelMet.

Adding new sources of data to an existing system is always a challenge. For example, the format of the new data might be incompatible with the existing data. This is true for event information in particular since there isn’t any generally accepted format, although some work is being done in that direction, see for example schema.org, EventsML or CitySDK. Other difficulties can arise from incompatibilities at the API level - even though a machine-friendly API is provided, it isn’t necessarily cut out for all possible use cases that application developers might come up with.

Open data has become a priority for the public sector in many countries. The idea is enticing - make your data open and let people innovate with it, developing applications that the public sector itself does not have the resources to implement. New York has NYC BigApps, Helsinki loves developers and there is even an Apps4Pirkanmaa competition, to name just a few. The HelMet case is a good example of a public organization’s willingness to expose data for public use - information about events taking place in HelMet’s network of libraries is provided using a machine-friendly API, which we decided to leverage in the Linked Events portal.

The challenges of open data

Despite the easy-to-use API, we still encountered a few problems while integrating our new data source, problems that probably are rather typical for developers trying to leverage open data. In our case, several vital pieces of information were missing from the event data that the API provides - location information, translations and so on. All of these issues would certainly be possible to fix, but it would probably take a long time for the data provider, a large public sector organization, to go through the hoops of procurement, IT development outsourcing and so forth. Because of time constraints, we ended up scraping a website for the missing pieces of information, an unnecessarily brittle step in what could otherwise have been a very simple integration.

Developers of applications that utilize open data are usually individuals or small, agile companies. When the providers of the open data are large organizations that cannot respond quickly to developers’ needs, there is going to be friction. Here are some tips for organizations that want developers to be able to smoothly leverage their open data sets:

  • Prefer open source components and universal data formats for developing APIs. This avoids provider lock-in and makes maintenance easier.
  • Outsource carefully and have someone in your organization with sufficient technical know-how oversee the project. Facilitate knowledge transfer by bringing consultants in-house and having them collaborate with your own people instead of doing development off-site.
  • Designate someone to be the “API maintainer”. This person should coordinate development, answer questions from developers, monitor API usage and watch out for potential problems. Provide this person’s contact information to developers. 
  • Open a public issue queue on for example GitHub. This provides a channel for developers to report issues, to discover what problems other developers have run into and and to see what progress has been made on resolving them.
  • Transparency is key - provide documentation, examples, a list of known bugs and so on. Consider open-sourcing your API. 

I think the push for making data open and accessible is an applaudable effort by the public sector. There have already been many beautiful applications built using open data - take, for example, BlindSquare or our own Linked Events aggregator. To make open data even more useful, data providers should seek to become more agile and responsive to developers’ needs. A public-facing API can’t be implemented and then forgotten about, it is something that needs to be supported and refined continuously.