About Nadaclair Language Technologies

Nadaclair Language Technologies is an industry leader in the creation of pedagogically-oriented grammar correction software. Our objective is to develop and promote affordable language learning tools to help students master the rules of written languages. NLT currently offers tools for the learning of French, English, and Spanish.

Our flagship program is BonPatron, a state-of-the art tool for learning the rules of French grammar. In 2007, we introduced SpellCheckPlus, a similar website with a focus on the common stumbling blocks of written English. More recently, we have introduced SpanishChecker which currently identifies grammatical and orthographic errors in Spanish.

All of our products are developed with a pedagogical focus in mind. It is our view that learners make greatest progress when they are actively involved in the grammar correction process. Unlike other similar products, the tools developed by Nadaclair Language Technolgies aim to teach students about grammar, rather them help them simply edit a specific text.

About our People

Nadaclair language technologies was co-founded by Dr. Terry Nadasdi and Dr. Stéfan Sinclair, two university professors with many years of experience in the area of language instruction. Dr. Nadasdi is a linguist who specializes in bilingualism and grammatical analysis, while Dr. Sinclair has a background in literary analysis and humanities computing.

Availability & Pricing

We are committed to providing free access to our full suite of high-quality language tools – these are valuable resources for people everywhere in the world. We also provide enhanced Pro versions of our tools that offer a range of significant advantages, including the following:

  • no advertising – the free versions are supported in part by advertising
  • text archiving – you can view any of your previously submitted texts
  • or private mode without text logging – all texts are logged in the free version
  • summary of errors
  • interactive grammar exercises for many errors
  • integrated vocabulary tools
  • resizable text editor – much more room available for editing your text
  • fullscreen editor – you can maximize the editor to the size of your browser window
  • and more...

The Pro versions of our tools are priced very reasonably at $15 for an individual annual subscription and $249 for classrooms of up to 30 students. For more information about pricing (for groups of various sizes), please contact us.


We have hundreds of private and institutional clients, including New York University, Johns Hopkins University, Carleton University, and many elementary/secondary schools and universities across Canada.

Contact Information

The best way to contact us is by email: mail@nadaclair.com.