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About mypy

Jukka Lehtosalo began work on mypy in 2012. The project borrows heavily from Jukka's earlier work on Alore, a Python-inspired language with an optional static type system.

In addition to Python and Alore, the design of mypy has been influenced by Java, C#, Typed Racket, Boo, Dart and the work of Jeremy G. Siek and Walid Taha on gradual typing.

Mypy Team

Jukka Lehtosalo

Jukka is the lead developer of mypy. Born and raised in Finland, Jukka works as a software engineer at Dropbox. Jukka created mypy while he was at the University of Cambridge Computer Laboratory in the UK as a PhD student. Before Cambridge, Jukka worked as a software engineer and later as a development manager for 9 years.

Jukka lives with his wife, two children, a cat, and a dog in Cambridge, England.

Guido van Rossum

Guido is Python's BDFL. Born and raised in the Netherlands, Guido works as a software engineer at Dropbox in San Francisco.

Ivan Levkivskyi

Ivan is an engineer working on mypy since 2016. Born and raised in Ukraine, spent 10 years in Switzerland working as a physicist, Ivan now works as a software engineer at Dropbox Ireland.

Michael J. Sullivan

Michael is an engineer at Dropbox in San Francisco. Born and raised in Wisconsin, Michael joined the mypy team after completing a PhD at Carnegie Mellon University's Principles of Programming Group.

Past Dropbox core team members

The following people have contributed to mypy as Dropbox employees, interns or contractors.

Non-Dropbox core team members

The following non-Dropboxers are considered core mypy contributors.


See the CREDITS file in the repository for a list of contributors.

Send us a pull request to join the team!


The development of mypy and the research behind mypy has been supported financially by the Finnish Cultural Foundation, the Academy of Finland, Emil Aaltonen Foundation, Engineering and Physical Sciences Research Council UK, University of Cambridge Computer Laboratory, ACM, and Dropbox.