Alternatives and similar repositories for optional

Users that are interested in optional are comparing it to the libraries listed below

• ned14 / outcome
  Provides very lightweight outcome<T> and result<T> (non-Boost edition)
  ☆757Updated 3 weeks ago
• foonathan / type_safe
  Zero overhead utilities for preventing bugs at compile time
  ☆1,590Updated 11 months ago
• mpark / variant
  C++17 `std::variant` for C++11/14/17
  ☆698Updated 2 years ago
• joboccara / NamedType
  Implementation of strong types in C++
  ☆803Updated 2 years ago
• gsl-lite / gsl-lite
  ISO C++ Core Guidelines Library implementation for C++98, C++11 up
  ☆952Updated 2 months ago
• mpark / patterns
  This is an experimental library that has evolved to P2688
  ☆677Updated 8 months ago
• TartanLlama / expected
  C++11/14/17 std::expected with functional-style extensions
  ☆1,725Updated last month
• ldionne / dyno
  Runtime polymorphism done right
  ☆1,015Updated 4 years ago
• martinmoene / expected-lite
  expected lite - Expected objects in C++11 and later in a single-file header-only library
  ☆482Updated last month
• serge-sans-paille / frozen
  a header-only, constexpr alternative to gperf for C++14 users
  ☆1,454Updated 3 weeks ago
• Naios / function2
  Improved and configurable drop-in replacement to std::function that supports move only types, multiple overloads and more
  ☆573Updated last month
• cbeck88 / visit_struct
  A miniature library for struct-field reflection in C++
  ☆583Updated 3 weeks ago
• boost-ext / ut
  C++20 μ(micro)/Unit Testing framework
  ☆1,371Updated 3 weeks ago
• eliaskosunen / scnlib
  scanf for modern C++
  ☆1,206Updated 3 weeks ago
• Naios / continuable
  C++14 asynchronous allocation aware futures (supporting then, exception handling, coroutines and connections)
  ☆846Updated last year
• beached / daw_json_link
  Fast, convenient JSON serialization and parsing in C++
  ☆495Updated 3 weeks ago
• foonathan / lexy
  C++ parsing DSL
  ☆1,114Updated this week
• ned14 / llfio
  P1031 low level file i/o and filesystem library for the C++ standard
  ☆972Updated last month
• bfgroup / Lyra
  A simple to use, composable, command line parser for C++ 11 and beyond
  ☆536Updated 2 weeks ago
• standardese / standardese
  A (work-in-progress) nextgen Doxygen for C++
  ☆960Updated last year
• joboccara / pipes
  Pipelines for expressive code on collections in C++
  ☆831Updated 9 months ago
• rollbear / strong_type
  An additive strong typedef library for C++14/17/20
  ☆452Updated 6 months ago
• boost-ext / te
  C++17 Run-time Polymorphism (Type Erasure) library
  ☆485Updated 4 months ago
• boostorg / pfr
  std::tuple like methods for user defined types without any macro or boilerplate code
  ☆1,418Updated last week
• rollbear / trompeloeil
  Header only C++14 mocking framework
  ☆857Updated 3 months ago
• stlab / libraries
  ASL libraries will be migrated here in the stlab namespace, new libraries will be created here.
  ☆674Updated this week
• tcbrindle / span
  Implementation of C++20's std::span for older compilers
  ☆362Updated 2 years ago
• foonathan / memory
  STL compatible C++ memory allocator library using a new RawAllocator concept that is similar to an Allocator but easier to use and write.
  ☆1,555Updated 2 months ago
• martinmoene / optional-lite
  optional lite - A C++17-like optional, a nullable object for C++98, C++11 and later in a single-file header-only library
  ☆409Updated 5 months ago
• andreasbuhr / cppcoro
  A library of C++ coroutine abstractions for the coroutines TS
  ☆406Updated 2 months ago