Release Cycle and Major Dependency Support Policy

This document describes a general plan for releasing the ASDF library, along with how long we intend to support each release. Moreover, it also describes our policy for how long we plan to support versions of CPython and NumPy. Note that this is a living document, and may be updated at any time.

Backwards Compatibility and Semantic Versioning

ASDF will maintain a backwards compatible API for all minor and patch versions. Any breaking API changes will only be included in major releases (where the major version number will be increased). We follow Semantic Versioning with one exception (LTS versions, described below).

Release Cycle

As ASDF is still under active development, it will continue to be developed on a rolling release cycle. This means that ASDF will not have a fixed release schedule, but rather will be released as needed.

However, we do intend to create and maintain designated “long-term support” (LTS) branches for at least major version of ASDF in a similar way as what is described for astropy in APE 2. This means that for every new major version of ASDF, say version a.0 we will designate and maintain a.0.x as the LTS branch of ASDF for at least one year. During this time we will try to ensure that the LTS branch receives bugfixes and has regular releases. After one year, we may decide to designate a new LTS branch for ASDF if no new major versions of ASDF have been released; otherwise, we will cease to maintain the old LTS branch in favor of the newer one(s). Aside from the LTS version(s), we will also maintain a rolling current version of ASDF. This support for these rolling versions will end when the next non-LTS version of ASDF is released.


Since this policy has not yet been implemented, we have not yet formally declared an LTS version for ASDF. Our plan is to declare 2.15 as an LTS version when it is released and move forward to actively working on ASDF 3.0 as our main development. Once 3.0 is released, it will also become a second LTS version of ASDF and we will continue to release bugfixes for ASDF 2.15 and 3.0 for at least one year past their release dates.

Dependency Support Policy

ASDF primarily depends on CPython and NumPy. As a scientific Python library, we have chosen to abide by the policy laid out in NEP 29. The following table summarizes this policy:




Jan 31, 2023



Apr 14, 2023



Jun 23, 2023



Jan 01, 2024



Apr 05, 2024



Jun 22, 2024



Dec 18, 2024



Apr 04, 2025



Apr 24, 2026



CPython and NumPy Drop Schedule

On Jan 31, 2023 drop support for NumPy 1.20 (initially released on Jan 31, 2021)
On Apr 14, 2023 drop support for Python 3.8 (initially released on Oct 14, 2019)
On Jun 23, 2023 drop support for NumPy 1.21 (initially released on Jun 22, 2021)
On Jan 01, 2024 drop support for NumPy 1.22 (initially released on Dec 31, 2021)
On Apr 05, 2024 drop support for Python 3.9 (initially released on Oct 05, 2020)
On Jun 22, 2024 drop support for NumPy 1.23 (initially released on Jun 22, 2022)
On Dec 18, 2024 drop support for NumPy 1.24 (initially released on Dec 18, 2022)
On Apr 04, 2025 drop support for Python 3.10 (initially released on Oct 04, 2021)
On Apr 24, 2026 drop support for Python 3.11 (initially released on Oct 24, 2022)

Support for Other Dependencies

ASDF also depends on several other Python packages. We currently do not have a formal policy for how long we intend to support these dependencies. However, we will try to support as many versions of these dependencies as possible.

In general, we will pin each of these dependencies from below with the oldest version that we guarantee will work with ASDF. We will also try to test against the latest version of each of these dependencies and release bugfixes to supported versions of ASDF on an as-needed basis. We will try our best to announce when we need to bump the support of these dependencies, and will always record doing so (and why) in the changelog.

If you find any issues with ASDF dependencies which affect a currently-supported version of ASDF, please open an issue in the ASDF repository.