---
title: "Convert YAML to JSON and back"
url: https://recursiveai.org/oneyaml/go/cookbook/yaml-to-json/
description: "Convert YAML to JSON in Go by reading it with oneyaml and writing it with encoding/json, and convert JSON back to YAML."
version: "1.0.0"
---

# Convert YAML to JSON and back

Turn a YAML file into JSON, or JSON into YAML, with oneyaml and the standard library’s `encoding/json`.

```go
package main

import (
	"encoding/json"
	"fmt"
	"log"

	oneyaml "oneyaml.dev/go"
)

func main() {
	// YAML to JSON: read into any, write with encoding/json.
	var v any
	err := oneyaml.Unmarshal([]byte(`name: web
ports: [80, 443]
tls: true
owner: ~
`), &v)
	if err != nil {
		log.Fatal(err)
	}
	out, err := json.MarshalIndent(v, "", "  ")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(string(out))

	// JSON to YAML: JSON is valid YAML 1.2, so read it and write YAML.
	var w any
	if err := oneyaml.Unmarshal([]byte(`{"name": "web", "ports": [80, 443], "env": {"LOG": "info"}}`), &w); err != nil {
		log.Fatal(err)
	}
	y, err := oneyaml.Marshal(w)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Print(string(y))
}
```

```text
{
  "name": "web",
  "owner": null,
  "ports": [
    80,
    443
  ],
  "tls": true
}
env:
  LOG: info
name: web
ports:
  - 80
  - 443
```

## Good to know

- Read into `any`: a mapping becomes `map[string]any`, a sequence `[]any`, an integer `int`, a float `float64` and `null` `nil`, all of which `encoding/json` writes.
- Go maps have no order, so both `encoding/json` and `Marshal` write their keys sorted. To keep the file’s order, read into a struct instead.
- A mapping with a key that isn’t a string becomes `map[any]any`, which `encoding/json` can’t write. Values JSON can’t hold, such as `.nan`, fail at `json.Marshal`.
- JSON is valid YAML 1.2, so `Unmarshal` reads JSON text directly.
- For typed data, skip `any`: `Unmarshal` into your struct and `json.Marshal` it.