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pypi / simplejson

simplejson

What changed in simplejson 4, from its official release notes, upgrade guides and advisories. Sources checked 2026-10-25.

1 breaking1 new APIs and options2 tooling5 fixes and other

See which of these apply to your code, ranked, in your agent:

npx @unstale/cli init

@unstale/cli 0.2.8 on npm

simplejson 49 changes

Breaking changes 1

  • Circular references introduced by custom JSON methods are now checked.

    4.2.0release notes

New APIs and options 1

  • Large integer stringification thresholds are supported in both encoders.

    4.2.0release notes

Tooling 2

  • Wheels are now built for CPython 3.15, making them available to developers using that Python version.

    4.2.0release notes

  • Wheel builds are now available for Python 2.7 on Windows platforms.

    4.1.1release notes

Fixes and other changes 5

  • The C scanner now uses the first-key error message.

    4.2.0release notes

  • The reported position for a control character is corrected when content precedes it.

    4.1.2release notes

  • Invalid \X escape errors report the offending character rather than the backslash.

    4.1.2release notes

  • The encoder handles non-finite Decimals the same way it handles floats.

    4.1.2release notes

  • Illegal trailing comma errors report the comma position.

    4.1.2release notes