Wasmer is powered by WebAssembly (opens in a new tab).

Wasmer supports many different backends, depending on your needs:

• Wasmer Native Backends:
  • Singlepass: incredibly fast compilation times, ideal for Blockchain Smart Contracts (opens in a new tab)
  • Cranelift: normal compilation times, good performance
  • LLVM: slow compilation times, great performance
• Other Runtimes:
  • V8: ideal for iOS, Android and development.
  • Wasmi: ideal for iOS, or any environment where only interpreters can run.
  • WAMR: ideal for IOT devices or any environment where only interpreters with limited memory can run.
  • JavaScriptCore: ideal for macOS. See announcement (opens in a new tab)
  • Browser: to target the web

Each of these backends supports different features and has varying support for operating systems and chipsets.

WebAssembly Features

• Bulk-memory operations: e.g. instructions with behavior similar to C's memmove and memset in WebAssembly;
• Multi-value return: return multiple values from functions making data transfer between host and guest simpler;
• Import & export of mutable globals: adds ability to import and export mutable globals;
• Non-trapping float-to-int conversions: this proposal would establish a convention for saturating operations, to avoid introducing trapping;
• Sign-extension operations: adds five new integer instructions for sign-extending 8-bit, 16-bit, and 32-bit values;
• Reference types: easier and more efficient interop with host environment;
• SIMD: Single Instruction, Multiple data: do heavy number crunching more quickly and/or with lower power usage.
• Threads: adds a new shared linear memory type and some new operations for atomic memory access;

Wasmer features

• Caching: compiled WebAssembly modules can be reused so subsequent runs of a Wasm file will have very little start up time;
• Metering: computation time and other resources can be monitored and limits set to control how the Wasm code runs. This is also known as "gas metering";
• Profiling: generate profiling data for WebAssembly code to analyze performance using tools like Linux perf;

Support of features by backend

WebAssembly features:

• ✅ Supported
• 🔄 In the works
• ❌ Not yet supported (please ping us if you need this feature!)

Wasmer features:

Backend support by Operating System

Backend support by Chipset

CLIRunners