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Python Changelog (3.6 → 3.14.0)

This changelog captures the major changes and important notes across Python versions from 3.6 to 3.14.0, focusing on significant language features, performance improvements, and breaking changes.

Python 3.14.0 (October 7, 2025)

Major Features

  • PEP 779: Free-threaded Python is officially supported - removes the Global Interpreter Lock (GIL) for true multi-threading
  • PEP 750: Template string literals (t-strings) for custom string processing using f-string-like syntax
  • PEP 649: Deferred evaluation of annotations - improves performance and semantics of type annotations
  • PEP 734: Multiple interpreters in the standard library - enables better isolation between Python interpreters
  • PEP 784: New compression.zstd module providing Zstandard compression algorithm support
  • PEP 758: except and except* expressions may now omit brackets for cleaner syntax
  • PEP 768: Zero-overhead external debugger interface for CPython

Performance & Implementation

  • Experimental JIT compiler included in official Windows and macOS binaries
  • Improved error messages with better traceback information
  • Built-in HMAC implementation with formally verified code from HACL* project
  • UUID versions 6-8 support and 40% faster generation for versions 3-5
  • Incremental garbage collection improvements

Platform & Build Changes

  • Official Android binary releases now available
  • Emscripten (WebAssembly) officially supported at tier 3
  • PGP signatures discontinued for releases (use Sigstore instead)

Python 3.13 (October 2024)

Major Features

  • Experimental free-threaded mode - no-GIL builds available (predecessor to 3.14's official support)
  • Improved interactive interpreter with better REPL experience
  • iOS support as an officially supported platform
  • PEP 594: Removed many deprecated modules from the standard library
  • PEP 703: Scalable garbage collection improvements

Performance

  • Significant interpreter optimizations
  • Faster startup time
  • Improved memory management

Python 3.12 (October 2023)

Major Features

  • PEP 695: Type parameter syntax - cleaner syntax for generic classes and functions
  • PEP 701: Syntactic formalization of f-strings - allows nested f-strings and better error messages
  • PEP 709: Comprehension inlining - improves performance of list/dict/set comprehensions
  • PEP 688: Making the buffer protocol accessible in Python code

Performance

  • 5% average performance improvement over 3.11
  • Reduced memory usage for certain operations
  • Better optimization of common patterns

Python 3.11 (October 2022)

Major Performance Release

  • Specializing adaptive interpreter - up to 25% faster on average
  • Faster function calls with optimized stack frames
  • Faster startup time - interpreter starts quicker
  • Improved error messages with precise error location indicators

Language Features

  • PEP 654: Exception groups and except* syntax
  • PEP 673: Self type for typing
  • PEP 646: Variadic generics for typing

Python 3.10 (October 2021)

Major Features

  • Structural pattern matching (PEP 634/635/636) - match/case statements
  • PEP 604: Union types with | operator (str | int instead of Union[str, int])
  • PEP 613: TypeAlias for explicit type alias declarations
  • Better error messages with more context

Performance

  • Faster attribute access
  • Optimized various built-in operations

Python 3.9 (October 2020)

Major Features

  • Dictionary union operators (PEP 584) (| and |=)
  • String methods: removeprefix() and removesuffix()
  • Built-in generic types - can use list[int] instead of List[int] from typing
  • PEP 593: Annotated type hints with metadata
  • PEP 615: IANA time zone database support via zoneinfo module
  • Annual release cycle adopted (changed from 18-month cycle)

Performance

  • Improved parsing speed with new PEG parser
  • Vectorcall protocol optimizations for built-ins

Python 3.8 (October 2019)

Major Features

  • Assignment expressions (PEP 572) (:=) - "walrus operator"
  • Positional-only parameters (PEP 570) (/)
  • Self-documenting f-strings (f"{variable=}") (PEP 572)
  • importlib.metadata for accessing package metadata
  • Runtime audit hooks for security monitoring

Performance

  • 20-50% speedup for many built-in methods
  • Shared memory support in multiprocessing
  • Optimized list creation (12% smaller on average)

Python 3.7 (June 2018)

Major Features

  • Dictionaries preserve insertion order - guaranteed by language spec
  • dataclasses - automatic class generation with type hints
  • contextvars - context variables for async programming
  • importlib.resources for accessing package resources
  • __future__.annotations - deferred annotation evaluation

Performance

  • Significant speed improvements across the board
  • Faster method calls
  • Optimized various built-in operations

Python 3.6 (December 2016)

Major Features

  • Formatted string literals (f-strings) - f"Hello {name}"
  • Underscores in numeric literals - 1_000_000 for readability
  • Variable annotations - type hints for variables (PEP 526)
  • Asynchronous generators and comprehensions
  • Secrets module added for secure random number generation

Performance

  • Dict implementation rewritten for better performance and memory usage
  • Faster function calls and method lookups

Important Migration Notes

End-of-Life Status

  • Python 3.6: EOL June 2023
  • Python 3.7: EOL June 2023
  • Python 3.8: EOL October 2024
  • Python 3.9: EOL October 2025
  • Python 3.10: EOL October 2026
  • Python 3.11: EOL October 2027
  • Python 3.12: EOL October 2028
  • Python 3.13: EOL October 2029
  • Python 3.14: EOL October 2030

Breaking Changes to Watch

  • 3.14: Major shift with free-threading support - may affect C extensions
  • 3.13: Many deprecated modules removed - check for removed stdlib modules
  • 3.12: Comprehension scoping changes may affect some code
  • 3.11: Some typing changes and new syntax requirements
  • 3.10: Pattern matching is a major new paradigm

Recommendations

  • Always test thoroughly when upgrading between major versions
  • Use tools like python -Wd to catch deprecation warnings
  • Consider using typing and type checkers for larger codebases
  • Take advantage of new features gradually rather than all at once

Last updated: October 2025