AI People Wiki

Builders & open source

Shantanu Jain

Works on language models, including training data and training infrastructure (since 2020), OpenAI

  • Works on language models, including training data and training infrastructure (since 2020), OpenAI12
  • Member of the mypy core team and typeshed maintainer, mypy51

Shantanu Jain, who publishes open-source work under the username hauntsaninja, has worked on language models at OpenAI since 2020, studying training data and building training infrastructure. Jain is the listed author of tiktoken, OpenAI's open-source BPE tokeniser for use with its models, and is a maintainer of mypy and typeshed and a CPython core developer.12345

At a glance

Current roles
Works on language models, including training data and training infrastructure (since 2020) +1 more
Companies
OpenAI, mypy
Sector
Company
Work listed
2
Sources cited
8
Profile reviewed

Career

Jain worked at Quora before joining OpenAI. Jain's site states that Jain has worked on language models at OpenAI since 2020, studying what data to train them on and building the infrastructure used to train them; Jain's GitHub profile lists OpenAI as the current organization.12

Open-source work

Jain is the listed author of tiktoken, a fast BPE tokeniser for use with OpenAI's models, whose README directs OpenAI staff with questions to Jain. The Python package first appeared on PyPI in December 2022 and has continued to receive releases, including version 0.14.0 in August 2026.364

Outside OpenAI, Jain works in the Python static typing ecosystem: the mypy CREDITS file lists Jain among the non-Dropbox core team members, and Jain also maintains typeshed and is a CPython core developer. Jain wrote pyp, a tool for running Python one-liners at the shell.5127

Work and contributions

  • tiktoken Open-source code

    Listed as the author of the tiktoken package in its pyproject.toml and on PyPI, where the first release (0.1.1) was published in December 2022.346

  • pyp Open-source code

    Author of pyp, a command-line tool for running Python at the shell, published on PyPI as pypyp since April 2020.781

Timeline

  1. Began working on language models at OpenAI.1
  2. Published the first release of pyp on PyPI under the package name pypyp.8
  3. Published the first release of tiktoken (0.1.1) on PyPI as its listed author.4
  4. Version 0.14.0 of tiktoken was published on PyPI, still listing Jain as author.4

Other documented roles

Roles the sources document that are not confirmed as current.

  • Previous employer before OpenAI, Quora1

Where they work

  • OpenAI 63 people in the wiki
  • mypy 1 person in the wiki

Suggest a correction or removal

Profiles cover public professional work only, and each statement cites a source. If something is out of date, missing or wrong, tell us and link a source. People can also ask for their profile to be corrected or removed.

References

8 sources · profile reviewed Oct 22, 2026 · data updated Oct 22, 2026

  1. Shantanu (hauntsaninja) — homepageShantanu Jain · Official page · accessed Oct 22, 2026
  2. hauntsaninja (Shantanu) on GitHubGitHub · Official page · accessed Oct 22, 2026
  3. openai/tiktoken pyproject.toml (package metadata and authors)openai/tiktoken (GitHub repository) · Repository · accessed Oct 22, 2026
  4. tiktoken on PyPI (package metadata and release history)Python Package Index · Release notes · accessed Oct 22, 2026
  5. python/mypy CREDITSpython/mypy (GitHub repository) · Repository · accessed Oct 22, 2026
  6. openai/tiktoken READMEopenai/tiktoken (GitHub repository) · Repository · accessed Oct 22, 2026
  7. hauntsaninja/pyp READMEhauntsaninja/pyp (GitHub repository) · Repository · accessed Oct 22, 2026
  8. pypyp on PyPI (package metadata and release history)Python Package Index · Release notes · accessed Oct 22, 2026