Release v6.0.0

The Vega-Altair team is pleased to announce the release of version 6.0.0. Firstly, we are grateful for the many returning contributors (@franzhaas, @dangotbanned, @dsmedia, @joelostblom, @tempdata73, @mattijn, @jonmmease, @eitanlees, @kurtmckee, @MarcoGorelli), and a special shoutout to all the new contributors (@JasonnnW3000, @edmundmiller, @jannisko, @stanmart, @star1327p, @baldwint, @daizutabi, @azjps, @joaopalmeiro, @bobot). You are all awesome!

In short what is included with the version 6 release of Altair.

• we now compile against Vega-Lite version 6 (to be specific, version 6.1.0) and provide support for Python 3.14.
• we have a new datasets module, altair.datasets, lazily access to datasets from https://github.com/vega/vega-datasets.
• we are now thread-safe, altair specifications should be stable after re-running.
• we improved docs and included new examples, eg. this faceted choropleth of habitat species across geographical counties https://altair-viz.github.io/gallery/maps_faceted_species.html.
• we improved the typing experiences.
• we migrated to uv as part of the infrastructure modernization and now have automated weekly builds.

We test all changes thoroughly, but nevertheless, if you encounter any issue or like to start a discussion. Please feel free!

Full details are available in the complete changelog below.

Breaking

• feat: Bump vega-lite>=6 by @franzhaas in #3831

Enhancements

• feat: Show python types in ValidationError messages by @dangotbanned in #3735
• feat: Update vega-lite to 5.21.0 by @dangotbanned in #3761
• feat: Show user_rows in MaxRowsError message by @dangotbanned in #3768
• feat: Allow numpy scalars in altair expressions by @stanmart in #3827
• feat: adds altair.datasets by @mattijn in #3848
• feat: preserve the empty property for the three operators (&, |, ~) by @mattijn in #3853
• feat: hashing of parameter and view names by @mattijn in #3851
• feat: Allow opening the editor without validating the spec by @joelostblom in #3869
• feat: require minimal vegafusion 2 and revert #3857 by @mattijn in #3885
• feat: add warning for deduplications by @mattijn in #3902

Bug Fixes

• fix(typing): Resolve LSP violation for ChartType.data by @dangotbanned in #3740
• fix: Replace circular import in schemapi.py by @dangotbanned in #3751
• fix: Include *(Datum|Value) in SchemaValidationError by @dangotbanned in #3750
• fix: Resolve multiple sphinx warnings by @dangotbanned in #3787
• fix(typing): overload in eval_block incorrectly showed True as the default for strict by @MarcoGorelli in #3855
• fix: import TypedDict from typing from python 3.15 by @mattijn in #3877
• fix: update typing_extensions dependency for Python < 3.15 by @daizutabi in #3881
• fix: Make .changed property optional in JupyterChart #3868 by @azjps in #3871
• fix(types): Change the height and width types of alt.Chart() from int to float by @joaopalmeiro in #3888
• fix: Repair vega export by @bobot in #3889

Documentation

• docs: Update LICENSE, fix copyright license year by @JasonnnW3000 in #3726
• docs: Add altair-upset link by @edmundmiller in #3786
• docs(example): Adds Confidence Interval Ellipses by @dangotbanned in #3747
• docs: Resolve geopandas.read_file(...) warnings by @dangotbanned in #3795
• docs: bump pyscript==2025.2.2 by @dangotbanned in #3797
• docs: fix broken links by @jannisko in #3802
• docs(example): Add Faceted map using Species Habitat dataset by @dsmedia in #3809
• docs: Add documentation for initial interval selection date ranges by @dsmedia in #3815
• docs: Update the waterfall_chart.py colors by @eitanlees in #3830
• docs: Clarify how order and on in the param section by @joelostblom in #3629
• docs: Improved docs on Transforms by @tempdata73 in #2655
• docs: More clearly illustrate parameter compositions by @joelostblom in #3628
• docs: new dataset source, from vega_dataset to altair.dataset by @mattijn in #3859
• docs: Correct some typos by @star1327p in #3904
• docs: improve docs how to return chart as html by @mattijn in #3849
• docs: Update the Lightning Viz link by @star1327p in #3839
• docs: Iris to penguins by @baldwint in #2231
• docs: docbuild warnings by @mattijn in #3850
• docs: Make the Code of Conduct link clickable by @star1327p in #3852
• docs: note within geoshape mark page to spatial data section by @mattijn in #3892
• docs: Remove whitespace after '*' so that text is rendered italic. by @thomascamminady in #3882
• docs: fix broken external reference URLs in examples by @dsmedia in #3898

Other Changes

• chore: Bump version to 5.6.0dev by @jonmmease in #3700
• ci: Temporal examples in vegafusion by @dangotbanned in #3702
• refactor(ruff): Apply TC006 fixes by @dangotbanned in #3706
• chore: fix ruff, mypy warnings by @dangotbanned in #3717
• ci: Switch from hatch, pip to uv in GitHub Actions by @dangotbanned in #3719
• ci(typing): Add bundled stubs to pyright.ignore by @dangotbanned in #3724
• ci: bump astral-sh/setup-uv from 4 to 5 in the github-actions group by @dependabot[bot] in #3727
• chore(ruff): Fix ruff warnings by @dangotbanned in #3736
• chore(typing): fix mypy>=1.14.0 warnings by @dangotbanned in #3739
• chore(ruff): Fix UP006 warnings during codegen by @dangotbanned in #3746
• refactor: Centralize Vega project versioning by @dangotbanned in #3720
• ci: Unpin pillow, allow >=10.0.0 by @dangotbanned in #3764
• chore(ruff): Update to 0.9.0 by @dangotbanned in #3766
• chore(ruff): Fix 0.9.2 lints by @dangotbanned in #3771
• chore: Add needs-triage to new bug reports by @dangotbanned in #3769
• test: Make skip_requires_pyarrow compatible w/ pytest.param by @dangotbanned in #3772
• build: Migrate from hatch to uv by @dangotbanned in #3723
• ci(typing): Disable mypy [annotation-unchecked] on examples by @dangotbanned in #3775
• ci(uv): Remove dynamic version from uv.lock by @dangotbanned in #3776
• ci(uv): bump mypy==1.15.0 by @dangotbanned in #3790
• ci: bump narwhals>=1.25.1 by @dangotbanned in #3792
• ci(uv): bump ruff==0.9.5 by @dangotbanned in #3799
• ci: bump narwhals>=1.26.0 by @dangotbanned in #3800
• ci: bump narwhals>=1.27.1 by @dangotbanned in #3807
• chore: Remove deprecated nw.from_native(..., strict=True) by @dangotbanned in #3811
• chore(typing): Follow-up fix _from_array_like by @dangotbanned in #3812
• ci(ruff): move exclude to extend-exclude by @dangotbanned in #3813
• chore: Add numfocus sponsor link by @joelostblom in #3814
• chore: Use organization-wide FUNDING.yml by @joelostblom in #3816
• chore: Bump vega-embed==7 by @franzhaas in #3829
• chore: Run typos and codespell against the codebase by @kurtmckee in #3840
• ci: bump astral-sh/setup-uv from 5 to 6 in the github-actions group by @dependabot[bot] in #3834
• ci: fix outdated ipython[kernel] dependency by @dangotbanned in #3861
• test: update test_datasets.py by @mattijn in #3857
• ci: add nightly builds system by @mattijn in #3858
• ci: fix mypy unused-ignore in tests by @mattijn in #3867
• ci: bump the github-actions group with 2 updates by @dependabot[bot] in #3866
• ci: use github raw and skip jsdelivr by @mattijn in #3875
• ci: bump actions/setup-python from 5 to 6 in the github-actions group by @dependabot[bot] in #3878
• ci: simplify nightly builds and do it weekly by @mattijn in #3887
• ci: improve weekly workflow version generation to resolve PEP 440 compliance error by @mattijn in #3897
• ci: bump astral-sh/setup-uv from 6 to 7 in the github-actions group by @dependabot[bot] in #3900
• ci: Test with minimum Narwhals version, bump minimum typing-extensions to 4.12.0 by @MarcoGorelli in #3899
• ci: improve body of weekly build by @mattijn in #3901
• ci: include python 3.14 rc3 to the GitHub action matrix by @mattijn in #3876
• ci: extra workflow to test free-threaded python by @mattijn in #3907
• ci: add pypi development release to weekly build by @mattijn in #3910
• ci: make sure artifact in weekly build contains data by @mattijn in #3911
• chore: v6 release branch by @mattijn in #3912

New Contributors

• @JasonnnW3000 made their first contribution in #3726
• @edmundmiller made their first contribution in #3786
• @jannisko made their first contribution in #3802
• @stanmart made their first contribution in #3827
• @star1327p made their first contribution in #3839
• @baldwint made their first contribution in #2231
• @daizutabi made their first contribution in #3881
• @azjps made their first contribution in #3871
• @joaopalmeiro made their first contribution in #3888
• @bobot made their first contribution in #3889

Full Changelog: v5.5.0...v6.0.0