Veer

The Inertia.js server-side protocol superset, for Rust.

Build modern single-page apps in React, Vue, or Svelte — without writing a JSON API, a client-side router, or a single fetch. Your Rust handlers return typed props, and the frontend hydrates as if the page was server-rendered. Because it was.

📖 Table of Contents

• ✨ What is Inertia, and why a Rust adapter
• 📦 Installation
• 🚀 Quick Start
• 🍳 Cookbook
• 🎛️ Feature Flags
• 🏗️ Architecture
• ⚠️ Caveats
• 🧪 Example App
• 🗺️ Status & Roadmap
• 🙌 Acknowledgements
• 🧪 Testing
• 📋 Changelog
• 🤝 Contributing
• 🔒 Security Vulnerabilities
• 💖 Support This Project
• ⭐ Star History
• 📄 License

✨ What is Inertia, and why a Rust adapter

Inertia.js is a glue layer that lets a classic server-rendered backend drive a modern SPA frontend. The server returns a page object (component name + props); the official Inertia client adapter for React/Vue/Svelte takes care of mounting the component, hydrating props, intercepting links, and making subsequent navigations into JSON XHRs.

veer is a clean-room Rust implementation of the server side of the Inertia v3 protocol. It targets axum out of the box; the protocol core is framework-agnostic, so adapters for other Rust web frameworks slot in beside it.

   ┌─────────────────────────┐                       ┌─────────────────────────┐
   │  Rust handler           │  ── page object ──▶   │  Inertia client (JS)    │
   │  inertia.render(...)    │       (JSON)          │  React / Vue / Svelte   │
   └─────────────────────────┘                       └─────────────────────────┘
              ▲                                                  │
              └─────────────  navigation XHR  ───────────────────┘

Highlights

• 🦀 Pure Rust server-side implementation of Inertia v3
• ⚡ First-class axum adapter (extractor + tower layer)
• 🧩 Framework-agnostic protocol core — drop new adapters in beside the axum one
• 📦 Partial reloads, deferred props, merge props, encrypted/clear history
• 🖥️ SSR via @inertiajs/server (Node or Bun) with graceful fallback
• ⚙️ Vite dev + production manifest integration that mirrors Laravel's @vite
• 📤 File uploads via typed InertiaForm + a streaming MultipartStream extractor
• ✅ Validation flash for validator and garde, plus a cookie-based session store
• 🪢 End-to-end TypeScript bindings: typed page props + Ziggy-style route helpers, generated from Rust

📦 Installation

Add veer to your Cargo.toml:

[dependencies]
veer = "0.1"

Or with cargo add:

cargo add veer

The default feature set includes the axum adapter. See Feature flags for everything else.

🚀 Quick Start

use axum::{routing::get, Router};
use veer::{Inertia, InertiaConfig, InertiaLayer, MinimalRootView};

#[tokio::main]
async fn main() {
    let cfg = InertiaConfig::new()
        .version(|| "1".into())
        .root_view(
            MinimalRootView::new()
                .title("Acme")
                .vite_entry("/src/main.tsx"),
        );

    let app = Router::new()
        .route("/", get(|inertia: Inertia| async move {
            inertia.render("Home", serde_json::json!({ "msg": "hello" }))
        }))
        .layer(InertiaLayer::new(cfg));

    let listener = tokio::net::TcpListener::bind("0.0.0.0:3000").await.unwrap();
    axum::serve(listener, app).await.unwrap();
}

The Inertia extractor reads the request. render(component, props) returns a builder. The layer handles the rest of the protocol — initial HTML on first load, JSON on XHR navigations, 409 for asset-version mismatches, 303 for POST-redirects, version checks, partial reloads.

🍳 Cookbook

async fn users_create(
    inertia: Inertia,
    InertiaForm(body): InertiaForm<NewUser>,
) -> impl IntoResponse {
    if let Err(errors) = body.validate() {
        return inertia.with_errors(errors).redirect("/users/new");
    }
    create_user(body).await;
    inertia
        .redirect("/users")
        .with_flash("success", serde_json::json!("User created"))
}

InertiaForm accepts application/json, application/x-www-form-urlencoded, and (with the multipart feature) multipart/form-data. The same handler works regardless of how the Inertia client serialized the request.

On the frontend, usePage().props.errors and usePage().props.flash are auto-populated whenever a SessionStore is configured — no extra wiring.

Enable the multipart feature and add UploadedFile fields to your typed struct:

use veer::{InertiaForm, UploadedFile};

#[derive(serde::Deserialize)]
struct CreateAvatar {
    user_id: String,
    avatar: UploadedFile,
}

async fn upload_avatar(
    inertia: Inertia,
    InertiaForm(form): InertiaForm<CreateAvatar>,
) -> impl IntoResponse {
    save_avatar(&form.user_id, &form.avatar.bytes, form.avatar.filename.as_deref()).await;
    inertia.redirect("/profile").with_flash("success", json!("Avatar updated"))
}

Inertia's useForm automatically switches to multipart/form-data when any field is a File or Blob. The same handler accepts JSON when no file is attached and multipart when one is — no separate route required.

For large or unbounded uploads where in-memory buffering isn't acceptable, use MultipartStream instead:

use veer::MultipartStream;

async fn huge_upload(MultipartStream(mut m): MultipartStream) -> impl IntoResponse {
    while let Some(field) = m.next_field().await.unwrap() {
        // pipe field.chunk().await into S3, disk, wherever — no buffering
    }
    // ...
}

async fn oauth_start(inertia: Inertia) -> impl IntoResponse {
    inertia.location("https://accounts.google.com/o/oauth2/v2/auth?...")
}

Returns 409 + X-Inertia-Location. The Inertia client honors this with a hard navigation.

inertia
    .render("Users/Index", serde_json::json!({ "users": users }))
    .lazy("stats", || async { json!({ "hits": load_stats().await }) })
    .deferred("expensive", "dashboard", || async { json!(load_expensive().await) })
    .merge("notifications")

Method	Behavior
lazy(key, closure) (alias optional)	Closure only runs when the client requests this key via a partial reload
deferred(key, group, closure)	First response advertises the key under deferredProps[group]; client then issues a follow-up reload that resolves it
merge(key)	Marks the key so the client merges the value into existing state instead of replacing
encrypt_history() / clear_history()	Set the Inertia v2+ history-state primitives
no_ssr()	Skip SSR for this response only

use veer::shared::shared_props_fn;

let cfg = InertiaConfig::new()
    .shared(shared_props_fn(|_req| async move {
        serde_json::json!({
            "auth": { "user": current_user().await },
            "app": { "name": "Acme" },
        })
    }));

Shared props merge under per-response props (handler props win on key collision).

Enable the ssr feature and point at the SSR service:

use veer::ssr::http::HttpSsrClient;

let cfg = InertiaConfig::new()
    .ssr(HttpSsrClient::new("http://127.0.0.1:13714/render"));

SSR failures fall back to client-side rendering by default. Set ssr_required(true) for hard-fail behavior.

For end-to-end SSR you'll usually combine this with ViteRootView (next entry) — ViteRootView inlines the SSR body verbatim and emits the <script data-page> mount the Inertia v3 client expects.

ViteRootView is a drop-in RootView that mirrors what Laravel's @vite + @viteReactRefresh Blade directives do. Two modes:

Dev — cross-origin script tags pointing at the Vite dev server, plus (opt-in) the React refresh preamble required when the HTML shell is served off-origin:

use veer::ViteRootView;

let cfg = InertiaConfig::new()
    .root_view(
        ViteRootView::dev()
            .title("Acme")
            .entry("frontend/app.tsx")
            .dev_server("http://localhost:5173")
            .react_refresh(true), // needed for @vitejs/plugin-react cross-origin
    );

Production — vite build writes dist/.vite/manifest.json. ViteRootView::production walks it from the entry, emitting the entry script, its CSS, and <link rel="modulepreload"> hints for transitively imported chunks:

use veer::{ViteManifest, ViteRootView};

let manifest = ViteManifest::load("dist/.vite/manifest.json")?;
let version  = manifest.hash(); // changes whenever any chunk hash changes

let cfg = InertiaConfig::new()
    .version(move || version.clone().into()) // bumps client asset cache on rebuild
    .root_view(
        ViteRootView::production()
            .title("Acme")
            .entry("frontend/app.tsx")
            .manifest(manifest)
            .asset_base("/build"),
    );

// Serve the built bundle next to the routes:
// .nest_service("/build", tower_http::services::ServeDir::new("dist"))

Wiring version to manifest.hash() means any rebuild auto-invalidates clients via the Inertia 409 + force-reload protocol — no manual version bumps.

For SSR in production, build the sidecar with vite build --ssr frontend/ssr.tsx and run the resulting bundle (bun dist/ssr/ssr.js or node …). Same :13714/render interface as dev.

Enable the ts feature and the frontend gets an auto-generated gen/ directory containing every page's props type, a discriminated Pages union, and one TypeScript module per controller with method-aware URL builders.

[dependencies]
veer = { version = "0.1", features = ["ts"] }
ts-rs = "10"

Annotate each prop struct and register it as a page:

use serde::Serialize;
use ts_rs::TS;

#[derive(Serialize, TS)]
#[ts(export)]
#[serde(rename_all = "camelCase")]
pub struct UsersIndexProps {
    pub users: Vec<User>,
}
veer::register_page!(UsersIndexProps, "Users/Index");

Then build your router using veer::Router — same fluent API as axum::Router, but every route gets a name and method so the codegen knows about it:

use veer::Method::*;

pub fn router() -> veer::Router<AppState> {
    veer::Router::new()
        .named_route(GET,    "users.index",   "/users",      users_index)
        .named_route(GET,    "users.show",    "/users/:id",  users_show)
        .named_route(GET,    "users.create",  "/users/new",  users_create)
        .named_route(POST,   "users.store",   "/users",      users_store)
        .named_route(PATCH,  "users.update",  "/users/:id",  users_update)
        .named_route(DELETE, "users.destroy", "/users/:id",  users_destroy)
}

// In main():
let app = router().build().with_state(state).layer(InertiaLayer::new(cfg));

build() returns a regular axum::Router, so .with_state / .layer / .merge / anything else just works. Same-path multi-method calls (GET + POST on /users) are merged into a single MethodRouter automatically — no panic on duplicate paths.

ts-rs mirrors #[serde(rename_all)] into the generated TypeScript, so the same struct drives both wire format and type. Route names follow the Laravel resource convention (index/show/create/store/update/destroy) so they don't collide with JavaScript reserved words.

Add a tiny binary that builds the router (so the runtime route registry populates) and then emits the bundle. Drop this in src/bin/gen-bindings.rs inside your app crate — cargo auto-discovers it:

// src/bin/gen-bindings.rs
fn main() {
    let _ = my_app::router().build();   // populate registry
    veer::bindings::generate_split("./frontend/gen").unwrap();
}

Generate with:

cargo run --bin gen-bindings

The codegen has to run inside your app binary (not a standalone CLI), because the route registry is populated at runtime by Router::build() and the page registrations are link-time inventory submissions — both only exist in your compiled crate.

On the frontend, import types and the per-controller action module:

import { usePage, router, Link } from "@inertiajs/react";
import { users, type UsersIndexProps } from "./gen";

export default function Index() {
  const { props } = usePage<UsersIndexProps>();
  return (
    <>
      <Link href={users.create.url()}>New user</Link>
      {props.users.map((u) => (
        <Link key={u.id} href={users.show.url({ id: u.id })}>{u.name}</Link>
      ))}
    </>
  );
}

Each action is a callable with .url and .form helpers:

Call	Returns
users.show({id: 1})	{ url: "/users/1", method: "get" } as const (visit definition)
users.show.url({id: 1})	"/users/1" (just the path string)
users.show.form({id: 1})	{ action: "/users/1", method: "get" } as const (props for <form>)

Generated layout:

frontend/gen/
  index.ts              protocol types, Pages, prop types, action namespace re-exports
  actions/
    users.ts            export const index, show, create, store, update, destroy
    posts.ts            …
    _root.ts            routes without a dotted prefix

Always<T> and Merge<T> collapse to T on the TypeScript side — the protocol's mergeProps / deferredProps arrays in the envelope carry the marker information instead.

Customize the output layout with the Split builder — rename the actions/ subdirectory, add a filename prefix/suffix, or flatten everything into the root:

veer::bindings::Split::new("./frontend/gen")
    .actions_dir("controllers")    // -> frontend/gen/controllers/
    .file_suffix("-controller")    // -> users-controller.ts, posts-controller.ts
    .generate()?;

actions_dir("") writes the controller files directly alongside index.ts; file_prefix is similarly available.

Need a single bundled file instead of the split tree? Use bindings::generate("./frontend/inertia.gen.ts") — same content, one file, with the route tree exposed as a nested routes.users.show(...) namespace.

Auto-regenerate on commit with lefthook. Add this to lefthook.yml at the repo root:

pre-commit:
  commands:
    veer-bindings:
      glob: "*.rs"
      run: cargo run -q --bin gen-bindings
      stage_fixed: true

stage_fixed: true re-adds the regenerated TS files to the commit so they never drift from the Rust source. Run lefthook install once per dev machine. Pair with a CI job that runs cargo run --bin gen-bindings && git diff --exit-code on PRs to fail-fast if someone bypasses the hook.

For apps without an existing session crate:

use veer::session::cookie::CookieSessionStore;

let cfg = InertiaConfig::new()
    .session(CookieSessionStore::new(env_secret()).secure(true));

HMAC-SHA256-signed, constant-time verification, one-shot semantics. For anything more elaborate, implement the SessionStore trait over your existing session crate (axum-login, redis, …) in ~30 lines.

If the app already runs tower-sessions, enable the tower-sessions feature and plug TowerSessionStore into the config. Flash data round-trips through whatever backend (Redis, Postgres, in-memory, …) tower-sessions is configured with.

use time::Duration;
use tower_sessions::{Expiry, MemoryStore, SessionManagerLayer};
use veer::{session::tower::TowerSessionStore, InertiaConfig, InertiaLayer};

let session_layer = SessionManagerLayer::new(MemoryStore::default())
    .with_expiry(Expiry::OnInactivity(Duration::minutes(30)));

let cfg = InertiaConfig::new().session(TowerSessionStore::new());

let app = axum::Router::new()
    // … routes …
    .layer(InertiaLayer::new(cfg))
    .layer(session_layer); // tower-sessions must wrap *outside* InertiaLayer

Flash is stored under a single key (_veer_flash by default; override with TowerSessionStore::new().key("...")).

🎛️ Feature Flags

Flag	Default	Effect
axum	on	Axum extractor + tower layer + InertiaForm body extractor
multipart	off	File upload support (UploadedFile, MultipartStream)
ssr	off	HTTP SSR client (reqwest)
cookie-session	off	Signed-cookie one-shot flash store
tower-sessions	off	Flash store backed by tower-sessions
validator	off	IntoErrorBag impl for validator::ValidationErrors
garde	off	IntoErrorBag impl for garde::Report
ts	off	End-to-end TypeScript bindings codegen (ts-rs + inventory)

Disabling a feature drops its transitive deps entirely.

🏗️ Architecture

┌────────────────────────────────────────────────────────┐
│  axum Router                                           │
│  ┌──────────────────────────────────────────────────┐  │
│  │ InertiaLayer                                     │  │
│  │   ├─ reads flash from SessionStore               │  │
│  │   ├─ injects config into request extensions      │  │
│  │   └─ on response: finalizes InertiaResponse,     │  │
│  │      writes flash, rewrites 302→303 on non-GET   │  │
│  └──────────────────────────────────────────────────┘  │
│                       │                                │
│                       ▼                                │
│        ┌───────────────────────────┐                   │
│        │  Inertia (extractor)      │                   │
│        │  inertia.render(...) →    │                   │
│        │  InertiaResponse builder  │                   │
│        └───────────────────────────┘                   │
└────────────────────────────────────────────────────────┘
              │
              ▼
   ┌──────────────────────────────────────┐
   │  Protocol core (framework-agnostic)  │
   │  • RequestInfo / PageObject          │
   │  • decide() state machine            │
   │  • prop resolver (partial reloads,   │
   │    deferred groups, merge keys)      │
   │  • Pluggable: RootView, SessionStore,│
   │    SsrClient, SharedProps            │
   └──────────────────────────────────────┘

The protocol core has zero I/O and zero framework deps — pure data structures and decision functions, exhaustively unit-tested. Adapters for other Rust frameworks (actix, rocket, salvo) can sit beside the axum one without touching it.

⚠️ Caveats

Always<T> and Merge<T> are detected at any depth and through any serialization path — typed #[derive(Serialize)] structs, serde_json::json!, hand-built Values, mixed maps. Only top-level matches affect the Inertia wire format though, because the protocol has no notion of a "nested merge prop". Wrappers placed deeper are still stripped from the JSON sent to the client; they just don't appear in mergeProps.

🧪 Example App

A complete end-to-end demo lives at examples/axum-react-todo/ — axum backend + React/Vite frontend, with validation, flash messages, and an in-memory todo store.

# Terminal 1 — Rust backend
cargo run -p axum-react-todo

# Terminal 2 — Vite dev server
cd examples/axum-react-todo
bun install
bun dev

🗺️ Status & Roadmap

veer is pre-1.0. The v0.1 protocol surface is complete (all Inertia v3 features: partial reloads, deferred props, merge props, encrypted/clear history, SSR, asset versioning, validation flash). Planned for follow-ups:

• Adapters for actix-web and rocket
• Typed route-param inference (today: string | number; goal: read each handler's Path extractor and emit the matching TS type)

Contributions, bug reports, and protocol-conformance fixtures welcome.

🙌 Acknowledgements

The protocol is Inertia.js by Jonathan Reinink and contributors. veer is an independent server-side implementation for Rust, modeled on the Laravel adapter's behavior.

🧪 Testing

cargo test --all-features

📋 Changelog

Please see CHANGELOG for more information on what has changed recently.

🤝 Contributing

Please see CONTRIBUTING for details. You can also join our Discord server to discuss ideas and get help: Discord Invite.

🔒 Security Vulnerabilities

Please report security vulnerabilities to security@climactic.co.

💖 Support This Project

Veer is free and open source, built and maintained with care. If this crate has saved you development time or helped power your application, please consider supporting its continued development.

🌟 Sponsors

Your logo here — Become a sponsor and get your logo featured in this README and on our website.

Interested in title sponsorship? Contact us at sponsors@climactic.co for premium placement and recognition.

⭐ Star History

📄 License

Dual-licensed under MIT or Apache 2.0 at your option. Please see MIT and APACHE for more information.