JSON to Rust Struct

What is JSON to Rust?

This tool converts a JSON sample into Rust structs derived for serde — the de facto standard (de)serialization framework in Rust. Each generated struct derives Debug, Serialize, Deserialize, so it works directly with serde_json::from_str / to_string with no extra glue code.

How it works

Nested JSON objects become their own pub struct, printed child-first. Field names are converted to snake_case, the Rust convention. When that conversion produces a name different from the raw JSON key — isActive becoming is_active — a #[serde(rename = "isActive")] attribute is added above that field so serde still maps to the original wire key. A field whose sample value was null is wrapped in Option<T>. Numbers become i64 or f64 — the generator always picks the widest safe default rather than guessing a smaller type like u32 or f32. A field name that's a Rust keyword (like type or match) is escaped as a raw identifier with r#.

Features

• #[derive(Debug, Serialize, Deserialize)] on every generated struct, ready for serde_json
• Automatic snake_case field renaming with a matching #[serde(rename = "...")] so the JSON wire format is untouched
• Nullable sample values become Option<T>, matching how serde represents absent/null JSON
• Rust keyword field names are escaped with r# raw identifiers instead of producing invalid code
• Struct name collisions with String, Vec, Option, or Box are renamed with a Data suffix

Example

Input: { "id": 101, "username": "alice_dev", "isActive": true, "signupBonus": null, "address": { "city": "Berlin", "zipCode": "10115" }, "tags": ["admin", "beta"] }

Output:

use serde::{Serialize, Deserialize};

#[derive(Debug, Serialize, Deserialize)]
pub struct Address {
    pub city: String,
    #[serde(rename = "zipCode")]
    pub zip_code: String,
}

#[derive(Debug, Serialize, Deserialize)]
pub struct Root {
    pub id: i64,
    pub username: String,
    #[serde(rename = "isActive")]
    pub is_active: bool,
    #[serde(rename = "signupBonus")]
    pub signup_bonus: Option<serde_json::Value>,
    pub address: Address,
    pub tags: Vec<String>,
}

Common errors

A null sample value produces Option<serde_json::Value> — untyped, since there's nothing concrete to infer. Narrow it to a real type once you know the field's actual shape, or the compiler won't help you catch misuse. serde_json::Value requires the serde_json crate as a dependency even when a field's type is otherwise fully typed. An empty sample array has no element to infer from and falls back to Vec<serde_json::Value>.

Best practices

Add #[serde(rename_all = "camelCase")] at the struct level instead of per-field rename attributes if every field in that struct needs the same camelCase-to-snake_case mapping — it's more concise for structs with many renamed fields. Narrow the numeric types (i32, u32, f32) once you know your actual value ranges — the generator defaults to the widest safe types, which cost more memory than necessary for large collections of structs.