C++

C++ Online Tools

Compiler Explorer, Wandbox, Quick-Bench, C++ Insights, and cpp.sh — what each does best and which to reach for first.

TL;DR — which to use

Godbolt — assembly inspection, compiler comparison.
Wandbox — full programs, stdin, trunk builds.
Quick-Bench — side-by-side micro-benchmarks.
C++ Insights — template instantiation, lambda desugaring.
cpp.sh — fastest 'does this compile?' check.

Feature comparison

FeatureCompiler ExplorerWandboxQuick C++ BenchmarkC++ Insightscpp.sh
run—
share
multi compiler———
libraries————
asm view————
Compiler Explorer
godbolt.org

Compile any code snippet and see assembly, IR, or optimization output. The #1 tool for understanding what compilers do.

Best for

  • Inspecting generated assembly
  • Comparing -O0 vs -O2 vs -O3 output
  • Comparing GCC vs Clang vs MSVC output
  • Demonstrating code to others (shareable URL)
  • Testing compiler flags in real-time
  • Checking C++ standard conformance
Pro tip: Ctrl+click on a source line highlights the corresponding assembly. Essential for understanding inlining and loop unrolling.
Wandbox
wandbox.org

Full program execution online with stdin support. Covers bleeding-edge trunk builds (GCC/Clang nightly).

Best for

  • Running complete programs (not just snippets)
  • Testing with GCC/Clang trunk (nightly builds)
  • stdin input to programs
  • Quick sharing of multi-file code
  • Checking C++26 features before they ship
Pro tip: Select 'HEAD' compiler for the latest GCC/Clang experimental builds — great for testing C++26 features.
Quick C++ Benchmark
quick-bench.com

Micro-benchmark two code snippets side-by-side in the browser. Powered by Google Benchmark.

Best for

  • Comparing two implementations at a glance
  • Demonstrating performance differences in discussions
  • Quick micro-benchmark prototyping
  • Sharing benchmark results with links
Pro tip: Always benchmark with -O2 or -O3, and use DoNotOptimize() or escape() to prevent the optimizer from eliminating your benchmark.
C++ Insights
cppinsights.io

Shows what the compiler actually sees: expanded templates, range-for loops, lambdas, structured bindings, coroutines.

Best for

  • Understanding template instantiations
  • Seeing lambda desugaring
  • Understanding range-for expansion
  • Teaching C++ internals
  • Debugging complex template errors
Pro tip: Paste a range-for loop to see the exact iterator protocol it expands to. Eye-opening for understanding begin()/end() customization points.
cpp.sh
cpp.sh

Simple, fast C++ runner. Zero friction — paste, run, share. No configuration needed.

Best for

  • Fastest 'does this compile?' check
  • Simple stdin/stdout programs
  • Teaching beginners
Pro tip: The simplest option for quick 'does this compile?' checks. No noise, no config.

Godbolt API

Compiler Explorer exposes a public REST API — the same one powering the Run button on every code snippet on this site.

POST https://godbolt.org/api/compiler/g141/compile
Content-Type: application/json

{
  "source": "#include <cstdio>\nint main() { puts(\"hello\"); }",
  "options": {
    "userArguments": "-O2 -std=c++23",
    "compilerOptions": { "executorRequest": true }
  }
}