# Releases and Version Compatibility
URL: /releases
OpenHTF release history from 1.0 (2016) to 1.6.x (2025), Python version requirements per release, what changed, and which release this documentation is verified against.
OpenHTF is released on PyPI from github.com/google/openhtf. This page tracks the releases that matter for compatibility; the changelog for TofuPilot's own products is at tofupilot.com/changelog.
Every page on this site shows a **Verified with OpenHTF x.y.z** line under its title. The examples were run against that release, currently **1.6.1**, on Python 3.12. When a page has no such line its content is version-independent.
Release
Date
Python
Notes
**1.6.1**
2025
≥ 3.10
Current PyPI release. Packaging fixes on top of 1.6.0.
**1.6.0**
March 2025
≥ 3.10
"Roll-up" release after two and a half years: Python 3.10 minimum, `protobuf>=5.28`, `tornado>=6,<6.5`, modern `pyproject.toml`, many accumulated fixes.
1.5.2
October 2022
≥ 3.7
`setup.py` fixes. Last release for Python 3.7–3.9.
1.5.1
October 2022
≥ 3.7
Deployment workflow fix.
1.5.0
October 2022
≥ 3.7
Numerous features and bug fixes; dropped Python 2. Diagnoses, branches and checkpoints matured in this line.
1.3.0
May 2018
2.7 / 3
Improved logging, new Angular web GUI (the Operator UI still used today).
1.2.x
January–March 2018
2.7 / 3
Incremental fixes.
1.1.0
July 2017
2.7
1.0.0 – 1.0.3
August–September 2016
2.7
Initial open-source releases.
`master` carries version `1.6.2` in `pyproject.toml` (unreleased as of September 2026). Install it with `pip install git+https://github.com/google/openhtf.git` if you need a fix that has not shipped.
**Python**: 3.10 or newer is required. Recreate the virtual environment.
**protobuf 5**: only matters if you use `mfg_inspector` or the proto output; regenerate any custom `_pb2` modules.
**tornado \< 6.5**: if another package in the environment needs a newer tornado, isolate OpenHTF in its own venv.
**API**: no intentional breaking changes to phases, measurements, plugs or output callbacks. Test scripts written for 1.5 run unchanged.
Pin OpenHTF and instrument libraries per station:
See Installation and Production deployment.