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JSON Benchmarks

This directory contains benchmarking tools to compare JSON against the standard library encoding/json when compiled to WebAssembly using TinyGo.

Build Script

The build.sh script compiles the WASM binaries with different JSON implementations.

Usage

# Build with JSON (default)
./build.sh

# Build with encoding/json (stdlib)
./build.sh stlib

Run the benchmark server

# Start the local server to serve the compiled WASM
go run ./web/server.go

You can then open http://localhost:6060 in a browser to see the benchmark results.

Output

The compiled WASM binary is output to web/public/main.wasm.

The script will display:

  • Uncompressed binary size
  • Gzipped size (for realistic deployment comparison)

Source Files

Both files implement the same functionality to ensure fair comparison.

Performance Results

Last updated: 2026-03-26

Go Benchmark (go test -bench)

Benchmark tinywasm/json encoding/json Δ allocs
Encode 268 ns/op 144 B/op 2 allocs 253 ns/op 80 B/op 1 allocs +1
Decode 308 ns/op 157 B/op 5 allocs 995 ns/op 376 B/op 8 allocs -3
RoundTrip 632 ns/op 317 B/op 8 allocs 1215 ns/op 376 B/op 8 allocs 0

Run: go test -bench=. -benchmem ./tests/...

WASM Binary Size

Implementation Binary Size (WASM + Gzip)
tinywasm/json ~27 KB
encoding/json (stdlib) ~119 KB

Analysis

tinywasm/json is 77% smaller (~27 KB vs ~119 KB) making it ideal for web apps where bundle size matters. By eliminating the reflect package, it not only significantly reduces the final WASM binary size, but also makes decoding ~3.2x faster and roundtripping ~1.9x faster than the standard library.

Use tinywasm/json when: Bundle size and raw decoding performance are critical, or running in restricted WASM environments. Use Stdlib when: You need to work dynamically with arbitrary unknown schemas (like map[string]any), as tinywasm/json is optimized strictly for predefined structs (fmt.Fielder).

See the main README for detailed benchmark results.