README
¶
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:8080 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
clients/tinyjson/main.go- Implementation using JSONclients/stdlib/main.go- Implementation using encoding/json (stdlib)
Both files implement the same functionality to ensure fair comparison.
Performance Results
Last updated: 2026-07-08
Go Benchmark (go test -bench)
| Benchmark | tinywasm/json | encoding/json | Δ allocs |
|---|---|---|---|
| Encode | 753.2 ns/op 80 B/op 1 allocs | 758.2 ns/op 80 B/op 1 allocs | 0 |
| Decode | 1414 ns/op 125 B/op 5 allocs | 3035 ns/op 376 B/op 8 allocs | -3 |
| RoundTrip | 2459 ns/op 221 B/op 7 allocs | 3673 ns/op 376 B/op 8 allocs | -1 |
Run:
go test -bench=. -benchmem ./tests/...
WASM Binary Size
Compiled with tinygo build -target wasm -no-debug -opt=z.
| Implementation | Uncompressed | Gzipped |
|---|---|---|
| tinywasm/json | 51 KB | 20 KB |
| encoding/json (stdlib) | 270 KB | 118 KB |
Run:
./build.sh(tinywasm/json) and./build.sh stlib(stdlib) from this directory.
Analysis
tinywasm/json is 83% smaller gzipped (20 KB vs 118 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 ~2.1x faster and roundtripping ~1.5x 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.Encodable/fmt.Decodable).
See the main README for detailed benchmark results.
Directories