The following public C API is new in 3.13 (beta 1, relative to 3.12), and as of this writing it looks either

• undocumented, or
• documented incorrectly. See the docs search page for what Sphinx thinks the type and fully-quilfied name of the symbol are; it should be a C entry without extraneous namespaces. (The details tend to matter for search, URLs, and Intersphinx links.)

See also: 3.14

• PY_MACCONFIG_H in Include/pymacconfig.h (header guards don't need docs)
• PY_MONITORING_EVENT_BRANCH in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_CALL in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_C_RAISE in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_C_RETURN in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_EXCEPTION_HANDLED in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_INSTRUCTION in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_JUMP in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_LINE in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_PY_RESUME in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_PY_RETURN in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_PY_START in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_PY_THROW in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_PY_UNWIND in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_PY_YIELD in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_RAISE in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_RERAISE in Include/cpython/monitoring.h
• PY_MONITORING_EVENT_STOP_ITERATION in Include/cpython/monitoring.h
• PY_MONITORING_IS_INSTRUMENTED_EVENT in Include/cpython/monitoring.h
• PyCF_OPTIMIZED_AST in Include/cpython/compile.h
• PyEval_GetFrameBuiltins in Include/ceval.h:25
• PyEval_GetFrameGlobals in Include/ceval.h:26
• PyEval_GetFrameLocals in Include/ceval.h:27
• PyExc_IncompleteInputError in Include/pyerrors.h:111
• PyExc_PythonFinalizationError in Include/cpython/pyerrors.h:129
• PyFrameLocalsProxy_Check in Include/cpython/pyframe.h
• PyFrameLocalsProxy_Type in Include/cpython/pyframe.h:6
• PyMonitoring_EnterScope in Include/cpython/monitoring.h:44
• PyMonitoring_ExitScope in Include/cpython/monitoring.h:48
• PyRefTracerEvent in Include/cpython/object.h:516, Include/cpython/object.h:519
• PyUnstable_AtExit in Include/cpython/pylifecycle.h:91
• PyUnstable_CopyPerfMapFile in Include/cpython/sysmodule.h:20
• PyUnstable_EXECUTABLE_KINDS in Include/cpython/pyframe.h
• PyUnstable_EXECUTABLE_KIND_BUILTIN_FUNCTION in Include/cpython/pyframe.h
• PyUnstable_EXECUTABLE_KIND_METHOD_DESCRIPTOR in Include/cpython/pyframe.h
• PyUnstable_EXECUTABLE_KIND_PY_FUNCTION in Include/cpython/pyframe.h
• PyUnstable_EXECUTABLE_KIND_SKIP in Include/cpython/pyframe.h
• PyUnstable_ExecutableKinds in Include/cpython/pyframe.h:45
• PyUnstable_GetExecutor in Include/cpython/optimizer.h:137 (now removed)
• PyUnstable_GetOptimizer in Include/cpython/optimizer.h:135 (now removed)
• PyUnstable_InterpreterState_GetMainModule in Include/cpython/pystate.h:11
• PyUnstable_Optimizer_NewCounter in Include/cpython/optimizer.h:145 (now removed)
• PyUnstable_Optimizer_NewUOpOptimizer in Include/cpython/optimizer.h:146 (now removed)
• PyUnstable_PerfTrampoline_CompileCode in Include/cpython/sysmodule.h:21
• PyUnstable_PerfTrampoline_SetPersistAfterFork in Include/cpython/sysmodule.h:22
• PyUnstable_Replace_Executor in Include/cpython/optimizer.h:129 (now removed)
• PyUnstable_SetOptimizer in Include/cpython/optimizer.h:133 (now removed)
• Py_ASNATIVEBYTES_BIG_ENDIAN in Include/cpython/longobject.h
• Py_ASNATIVEBYTES_DEFAULTS in Include/cpython/longobject.h
• Py_ASNATIVEBYTES_LITTLE_ENDIAN in Include/cpython/longobject.h
• Py_ASNATIVEBYTES_NATIVE_ENDIAN in Include/cpython/longobject.h
• Py_ASNATIVEBYTES_REJECT_NEGATIVE in Include/cpython/longobject.h
• Py_ASNATIVEBYTES_UNSIGNED_BUFFER in Include/cpython/longobject.h
• Py_ATOMIC_H in Include/pyatomic.h (header guards don't need docs)
• Py_CAN_START_THREADS in Include/pyport.h:463
• Py_C_RECURSION_LIMIT in Include/cpython/pystate.h:215 (removed in 3.14)
• Py_MOD_GIL_NOT_USED in Include/moduleobject.h:69
• Py_MOD_GIL_USED in Include/moduleobject.h:69
• Py_MONITORING_H in Include/monitoring.h (header guards don't need docs)
• Py_OPTIMIZER_H in Include/cpython/optimizer.h (header guards don't need docs)
• Py_TPFLAGS_INLINE_VALUES in Include/object.h:632
• Py_TRASHCAN_HEADROOM in Include/cpython/object.h:463 (removed in GH-124715: Move trashcan mechanism into Py_Dealloc #132280)
• CO_NO_MONITORING_EVENTS in Include/cpython/code.h:192

Some more are generated by configure, I guess that's low priority:

• HAVE_CLOCK_T in ./pyconfig.h:138
• HAVE_CLOSEFROM in ./pyconfig.h:138
• HAVE_GETGRENT in ./pyconfig.h:138
• HAVE_GRANTPT in ./pyconfig.h:515
• HAVE_POSIX_OPENPT in ./pyconfig.h:849
• HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSEFROM_NP in ./pyconfig.h:849
• HAVE_PROCESS_VM_READV in ./pyconfig.h:849
• HAVE_PTSNAME in ./pyconfig.h:957
• HAVE_PTSNAME_R in ./pyconfig.h:957
• HAVE_SOCKLEN_T in ./pyconfig.h:957
• HAVE_SYS_TIMERFD_H in ./pyconfig.h:1406
• HAVE_TIMERFD_CREATE in ./pyconfig.h:1406
• HAVE_UNLOCKPT in ./pyconfig.h:1406
• HAVE___UINT128_T in ./pyconfig.h:1582
• WITH_MIMALLOC in ./pyconfig.h:1867

Linked PRs

• gh-118915: Add/fix docs entries for some new 3.13 C API #124134
• [3.13] gh-118915: Add/fix docs entries for some new 3.13 C API (GH-124134) #124244
• gh-118915: C API: Document frame locals proxies. #127720
• [3.13] gh-118915: C API: Document frame locals proxies. (GH-127720) #127831
• gh-118915: Add document of PY_MONITORING_IS_INSTRUMENTED_EVENT #128026
• gh-118915: Document PyUnstable_InterpreterState_GetMainModule #128483
• [3.13] gh-118915: Document PyUnstable_InterpreterState_GetMainModule (GH-128483) #128677
• gh-118915: C API: Document compiler flag macros #129028
• [3.13] gh-118915: C API: Document compiler flag macros (GH-129028) #129086
• gh-118915: Fix bad link in documentation #129691
• [3.13] gh-118915: Fix bad link in documentation (GH-129691) #129723
• [3.13] gh-118915: Document PY_MONITORING_IS_INSTRUMENTED_EVENT (GH-128026) #131424