Mock JSON · json.Marshal · Gin · Echo — 3 modes
Convert Go to JSON
Mock data, Marshal
snippets or framework.
Generate mock JSON from a Go struct, get
json.Marshal
snippets for every scenario, or get Gin, Echo and
net/http JSON response patterns.
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Go struct → mock JSON
json.Marshal · NewEncoder snippets
Gin · Echo · net/http patterns
Always free
Go to JSON — 3 modes
100% client-side
Go struct input
Ready
json.Marshal vs json.NewEncoder
Two approaches — choose based on where you need the JSON.
| json.Marshal | json.NewEncoder | |
|---|---|---|
| Output | []byte | Writes to io.Writer directly |
| Best for | Storing in a variable, Redis, strings | HTTP responses, files, buffers |
| Memory | Full buffer in memory | Streams — more efficient for large payloads |
| Pretty | json.MarshalIndent(v, "", " ") | enc.SetIndent("", " ") |
| Newline | No trailing newline | Adds newline after each Encode() call |
Go parsed in your
browser. No compiler needed.
The mock JSON mode uses a field-level regex parser — no need to compile Go. It reads struct field names and types, and generates realistic JSON values. The snippets and framework patterns are generated from your selection — no API call, no server round-trip.
Struct parser
Reads Go struct field names and types — handles json tags for key names and pointer types for nullable fields.
Marshal vs Encoder
Both patterns covered — json.Marshal for byte slices and strings, json.NewEncoder for writers (HTTP, files).
3 frameworks
net/http, Gin and Echo — the three most popular Go web frameworks, each with their idiomatic JSON response pattern.
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Frequently asked questions
How do I convert a Go struct to JSON?
Use json.Marshal: data, err := json.Marshal(myStruct); if err != nil { log.Fatal(err) }. This returns a []byte. Convert to string with string(data). For pretty output: json.MarshalIndent(myStruct, "", " "). Select the Snippets mode for the complete pattern with error handling.
How do I return JSON from a Go HTTP handler?
Set the Content-Type header, then use json.NewEncoder: w.Header().Set("Content-Type", "application/json"); if err := json.NewEncoder(w).Encode(data); err != nil { http.Error(w, err.Error(), 500) }. In Gin: c.JSON(200, data). In Echo: return c.JSON(200, data). Select the Frameworks mode for complete handler examples.
What is the difference between json.Marshal and json.NewEncoder?
json.Marshal encodes to []byte in memory — use when you need JSON as a variable, for Redis/cache, or string conversion. json.NewEncoder writes directly to an io.Writer without a temporary buffer — more efficient for HTTP responses and file output, especially for large payloads.