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WebAssembly with Zig

  • WebAssembly support for Zig is excellent.
  • Zig uses LLVM, thus it provides wasm32 target architecture.

Install Zig

To install Zig, follow the instructions here:

Zig Code

Create a simple Zig program that calculates the fibonacci sequence of an integer input:

const std = @import("std");

fn fibonacci(i: u64) u64 {
if (i <= 1) return i;
return fibonacci(i - 1) + fibonacci(i - 2);

fn print_fibonacci(w: anytype, s: []const u8) !void {
const i = try std.fmt.parseUnsigned(u64, s, 10);
try w.print("Fibonacci sequence number at index {d} is {d}\n", .{i, fibonacci(i)});

pub fn main() !void {
const alloc: std.mem.Allocator = std.heap.page_allocator;

var args = try std.process.argsAlloc(alloc);

const stdout =;
defer stdout.close();

const out = stdout.writer();

try out.print("Zig - Fibonacci sequence example\n", .{});

const indexes = args[1..];
if (indexes.len > 0) {
for (indexes) |arg| {
try print_fibonacci(out, arg);
} else {
const stdin =;
defer stdin.close();

try out.print("Enter a non-negative number:\n", .{});
var buf: [19]u8 = undefined;
if (try stdin.reader().readUntilDelimiterOrEof(&buf, '\n')) |arg| {
try print_fibonacci(out, arg);
} else {
std.debug.print("failed to read from stdin", .{});

Access the Zig codex repository for code samples, including the fibonacci example.

Compile the Zig code

zig run main.zig

Compile Zig to Wasm

zig build-exe main.zig -target wasm32-wasi

Run with Enarx

enarx run main.wasm