diff --git a/Cargo.lock b/Cargo.lock
index 43c9459..c6123fd 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -451,6 +451,22 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
 
+[[package]]
+name = "errno"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f258a7194e7f7c2a7837a8913aeab7fd8c383457034fa20ce4dd3dcb813e8eb8"
+dependencies = [
+ "libc",
+ "windows-sys",
+]
+
+[[package]]
+name = "fastrand"
+version = "2.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "25cbce373ec4653f1a01a31e8a5e5ec0c622dc27ff9c4e6606eefef5cbbed4a5"
+
 [[package]]
 name = "fnv"
 version = "1.0.7"
@@ -806,6 +822,12 @@ dependencies = [
  "vcpkg",
 ]
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.4.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "969488b55f8ac402214f3f5fd243ebb7206cf82de60d3172994707a4bcc2b829"
+
 [[package]]
 name = "lock_api"
 version = "0.4.11"
@@ -1108,6 +1130,19 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"
 
+[[package]]
+name = "rustix"
+version = "0.38.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc99bc2d4f1fed22595588a013687477aedf3cdcfb26558c559edb67b4d9b22e"
+dependencies = [
+ "bitflags 2.4.1",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys",
+]
+
 [[package]]
 name = "rustversion"
 version = "1.0.14"
@@ -1278,13 +1313,13 @@ dependencies = [
  "serde",
  "serde_json",
  "sysinfo",
+ "tempfile",
  "thiserror",
  "time",
  "tokio",
  "tokio-stream",
  "tracing",
  "tracing-subscriber",
- "xshell",
 ]
 
 [[package]]
@@ -1325,6 +1360,19 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "tempfile"
+version = "3.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7ef1adac450ad7f4b3c28589471ade84f25f731a7a0fe30d71dfa9f60fd808e5"
+dependencies = [
+ "cfg-if",
+ "fastrand",
+ "redox_syscall",
+ "rustix",
+ "windows-sys",
+]
+
 [[package]]
 name = "text-size"
 version = "1.1.1"
@@ -1782,18 +1830,3 @@ name = "windows_x86_64_msvc"
 version = "0.48.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ed94fce61571a4006852b7389a063ab983c02eb1bb37b47f8272ce92d06d9538"
-
-[[package]]
-name = "xshell"
-version = "0.2.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ce2107fe03e558353b4c71ad7626d58ed82efaf56c54134228608893c77023ad"
-dependencies = [
- "xshell-macros",
-]
-
-[[package]]
-name = "xshell-macros"
-version = "0.2.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e2c411759b501fb9501aac2b1b2d287a6e93e5bdcf13c25306b23e1b716dd0e"
diff --git a/Cargo.toml b/Cargo.toml
index d351319..5c07c03 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,10 +19,10 @@ rnix = "0.11"
 serde = "1"
 serde_json = "1"
 sysinfo = "0.29"
+tempfile = "3"
 thiserror = "1"
 time = { version = "0.3", features = ["serde"] }
 tokio = { version = "1", features = ["full"] }
 tokio-stream = "0.1"
 tracing = "0.1"
 tracing-subscriber = "0.3"
-xshell = "0.2"
diff --git a/src/http/error.rs b/src/http/error.rs
index aba8bc5..5a55dbe 100644
--- a/src/http/error.rs
+++ b/src/http/error.rs
@@ -13,7 +13,7 @@ pub enum AppError {
     Client {
         status: StatusCode,
         code: &'static str,
-        message: &'static str,
+        message: String,
     },
 
     #[error("docker error: {0}")]
@@ -22,9 +22,6 @@ pub enum AppError {
     #[error("file error: {0}")]
     FileError(#[from] std::io::Error),
 
-    #[error("shell error: {0}")]
-    ShellError(#[from] xshell::Error),
-
     #[error("unexpected internal error: {0}")]
     Internal(#[from] anyhow::Error),
 
@@ -54,11 +51,6 @@ impl IntoResponse for AppError {
                 code: "file-error".to_string(),
                 message: err.to_string(),
             },
-            AppError::ShellError(err) => ErrorInfo {
-                status: StatusCode::INTERNAL_SERVER_ERROR,
-                code: "shell-error".to_string(),
-                message: err.to_string(),
-            },
             AppError::Template(err) => ErrorInfo {
                 status: StatusCode::INTERNAL_SERVER_ERROR,
                 code: "template-error".to_string(),
diff --git a/src/node/error.rs b/src/node/error.rs
index a5d9852..0a49292 100644
--- a/src/node/error.rs
+++ b/src/node/error.rs
@@ -14,7 +14,7 @@ impl From<StackError> for AppError {
             StackError::NotFound => AppError::Client {
                 status: StatusCode::NOT_FOUND,
                 code: "stack-not-found",
-                message: "stack not found",
+                message: "stack not found".to_string(),
             },
         }
     }
diff --git a/src/node/git.rs b/src/node/git.rs
index 1e3e42c..19e18be 100644
--- a/src/node/git.rs
+++ b/src/node/git.rs
@@ -71,12 +71,14 @@ impl ThreadSafeRepository {
         Repository::open(&self.path)
     }
 
-    pub fn commit_file(&self, path: &Path, message: &str) -> Result<()> {
+    pub fn commit_files(&self, paths: &[&Path], message: &str) -> Result<()> {
         let repository = self.repository()?;
 
         // Commit file
         let mut index = repository.index()?;
-        index.add_path(path)?;
+        for path in paths {
+            index.add_path(path)?;
+        }
         let oid = index.write_tree()?;
         let tree = repository.find_tree(oid)?;
         let head = repository.head()?;
diff --git a/src/node/stack.rs b/src/node/stack.rs
index 4c99978..f6bf662 100644
--- a/src/node/stack.rs
+++ b/src/node/stack.rs
@@ -2,17 +2,23 @@ use super::{
     container::ContainerInfo, error::StackError, git::ThreadSafeRepository,
     nix::parse_arion_compose,
 };
-use crate::http::error::Result;
+use crate::http::error::{AppError, Result};
+use axum::http::StatusCode;
 use bollard::{container::ListContainersOptions, service::ContainerSummary, Docker};
+use futures_util::future::try_join;
 use serde::Serialize;
 use std::{
     collections::HashMap,
     path::{Path, PathBuf},
+    process::Command,
 };
+use tempfile::tempdir;
 use tokio::fs;
-use xshell::Shell;
 
 const COMPOSE_FILE: &str = "arion-compose.nix";
+const PACKAGE_FILE: &str = "arion-pkgs.nix";
+const PACKAGE_CONTENTS: &str = r#"import <nixpkgs> { system = "x86_64-linux"; }
+"#;
 
 async fn is_stack(dir: &Path) -> Result<bool> {
     Ok(fs::try_exists(dir.join(COMPOSE_FILE)).await?)
@@ -148,26 +154,108 @@ pub fn commit_compose(
     message: &str,
 ) -> Result<()> {
     let compose_path = format!("{}/{}", stack_name, COMPOSE_FILE);
-    repository.commit_file(&PathBuf::from(compose_path), message)?;
+    repository.commit_files(&[&PathBuf::from(compose_path)], message)?;
     Ok(())
 }
 
+pub async fn create_new(
+    repository: ThreadSafeRepository,
+    stack_name: &str,
+    source: &str,
+) -> Result<()> {
+    // Calculate stack directory and create it
+    let stack_path = repository.path.join(stack_name);
+    fs::create_dir_all(&stack_path).await?;
+
+    // Create package file and compose file
+    try_join(
+        fs::write(stack_path.join(PACKAGE_FILE), PACKAGE_CONTENTS),
+        fs::write(stack_path.join(COMPOSE_FILE), source),
+    )
+    .await?;
+
+    // Commit everything
+    repository.commit_files(
+        &[
+            &PathBuf::from(format!("{}/{}", stack_name, PACKAGE_FILE)),
+            &PathBuf::from(format!("{}/{}", stack_name, COMPOSE_FILE)),
+        ],
+        format!("Created stack {}", stack_name).as_str(),
+    )?;
+
+    Ok(())
+}
+
+pub async fn check_compose(arion_bin: &Path, source: &str) -> Result<()> {
+    // Check that it's a valid nix tree
+    rnix::Root::parse(source)
+        .ok()
+        .map_err(|_| AppError::Client {
+            status: StatusCode::NOT_ACCEPTABLE,
+            code: "failed-nix-parse",
+            message: "The provided source is not valid Nix".to_string(),
+        })?;
+
+    // Create a temporary stack and check that it generates a YAML tree
+    let dir = tempdir()?;
+    let path = dir.path();
+
+    // Create package file and compose file
+    try_join(
+        fs::write(path.join(PACKAGE_FILE), PACKAGE_CONTENTS),
+        fs::write(path.join(COMPOSE_FILE), source),
+    )
+    .await?;
+
+    let cmd = arion(arion_bin, path, StackCommand::Test)?;
+
+    dir.close()?;
+
+    if let CommandStatus::Failure(_, err) = cmd {
+        Err(AppError::Client {
+            status: StatusCode::NOT_ACCEPTABLE,
+            code: "failed-arion-check",
+            message: err,
+        })
+    } else {
+        Ok(())
+    }
+}
+
+pub enum CommandStatus {
+    Success(String, String),
+    Failure(String, String),
+}
+
+fn arion(arion_bin: &Path, path: &Path, action: StackCommand) -> Result<CommandStatus> {
+    let output = Command::new(arion_bin)
+        .args(action.command())
+        .current_dir(path)
+        .output()?;
+
+    // Convert stdout and stderr to String
+    let stdout_str = String::from_utf8_lossy(&output.stdout).to_string();
+    let stderr_str = String::from_utf8_lossy(&output.stderr).to_string();
+
+    if output.status.success() {
+        Ok(CommandStatus::Success(stdout_str, stderr_str))
+    } else {
+        Ok(CommandStatus::Failure(stdout_str, stderr_str))
+    }
+}
+
 pub async fn command(
     base_dir: &Path,
     stack_name: &str,
     arion_bin: &Path,
     action: StackCommand,
-) -> Result<()> {
+) -> Result<CommandStatus> {
     let dir = base_dir.join(stack_name);
     if !is_stack(&dir).await? {
         return Err(StackError::NotFound.into());
     }
 
-    let sh = Shell::new()?;
-    sh.change_dir(dir);
-    sh.cmd(arion_bin).args(action.command()).run()?;
-
-    Ok(())
+    arion(arion_bin, &dir, action)
 }
 
 pub enum StackCommand {
@@ -175,6 +263,7 @@ pub enum StackCommand {
     Start,
     Stop,
     Restart,
+    Test,
 }
 
 impl StackCommand {
@@ -184,6 +273,7 @@ impl StackCommand {
             StackCommand::Start => &["up", "-d"],
             StackCommand::Stop => &["stop"],
             StackCommand::Restart => &["restart"],
+            StackCommand::Test => &["config"],
         }
     }
 }
diff --git a/src/route/stack.rs b/src/route/stack.rs
index 538b98e..fc36157 100644
--- a/src/route/stack.rs
+++ b/src/route/stack.rs
@@ -6,7 +6,8 @@ use crate::{
     node::{
         container::ContainerInfo,
         stack::{
-            command, commit_compose, get_compose, get_containers, write_compose, StackCommand,
+            check_compose, command, commit_compose, create_new, get_compose, get_containers,
+            write_compose, StackCommand,
         },
     },
     AppState,
@@ -63,6 +64,21 @@ async fn new_stack_page() -> impl IntoResponse {
     CreateTemplate {}
 }
 
+#[derive(Deserialize)]
+struct CreateStackForm {
+    name: String,
+    source: String,
+}
+
+async fn create_stack(
+    State(state): State<AppState>,
+    Form(form): Form<CreateStackForm>,
+) -> Result<Redirect, AppError> {
+    create_new(state.repository, &form.name, &form.source).await?;
+
+    Ok(Redirect::to(format!("/stack/{}/", form.name).as_str()))
+}
+
 #[derive(Deserialize)]
 struct EditStackForm {
     source: String,
@@ -84,7 +100,7 @@ async fn edit_stack(
         return Err(AppError::Client {
             status: StatusCode::BAD_REQUEST,
             code: "invalid-source",
-            message: "provided stack source is empty",
+            message: "provided stack source is empty".to_string(),
         });
     };
 
@@ -106,7 +122,15 @@ async fn edit_stack(
     )
     .await?;
 
-    Ok(Redirect::to("./")) as Result<Redirect, AppError>
+    Ok(Redirect::to("./"))
+}
+
+async fn check_stack_file(
+    State(state): State<AppState>,
+    body: String,
+) -> Result<StatusCode, AppError> {
+    check_compose(&state.arion_bin, &body).await?;
+    Ok(StatusCode::NO_CONTENT)
 }
 
 macro_rules! stack_command {
@@ -120,7 +144,8 @@ macro_rules! stack_command {
 
 pub(super) fn router() -> Router<AppState> {
     Router::new()
-        .route("/_/new", get(new_stack_page))
+        .route("/_/new", get(new_stack_page).post(create_stack))
+        .route("/_/check", post(check_stack_file))
         .route(
             "/:stack",
             get(|Path(stack_name): Path<String>| async move {
diff --git a/static/js/ace.mjs b/static/js/ace.mjs
index a191537..d8428e7 100644
--- a/static/js/ace.mjs
+++ b/static/js/ace.mjs
@@ -2,6 +2,8 @@ import "../vendor/ace/ace.js";
 import { findNearestParent } from "./node-utils.mjs";
 
 export default class Editor {
+	editor;
+
 	/**
 	 * Create a new editor
 	 * @param {string} elementID ID of element to replace with the editor
diff --git a/templates/stack/get-one.html b/templates/stack/get-one.html
index 49f0cf5..a66fc36 100644
--- a/templates/stack/get-one.html
+++ b/templates/stack/get-one.html
@@ -41,6 +41,7 @@
 			<div class="row">
 				<input style="flex:1" name="commit_message" type="text"
 					placeholder="What did you change?" />
+				<div id="editor-extra"></div>
 				<button class="wide" type="submit">Deploy</button>
 			</div>
 		</form>
@@ -104,7 +105,27 @@
 <script type="module">
 	import Editor from "/static/js/ace.mjs";
 
-	new Editor("editor");
+	const editor = new Editor("editor");
+
+	/* Add extra buttons */
+	const extraContainer = document.getElementById("editor-extra");
+
+	/* Check button */
+	const checkButton = document.createElement("button");
+	checkButton.appendChild(document.createTextNode("Check"));
+	checkButton.type = "button";
+	checkButton.addEventListener("click", async () => {
+		const body = editor.editor.getValue();
+		const response = await fetch("/stack/_/check", {
+			method: "POST",
+			headers: {
+				"Accept": "application/json",
+				"Content-Type": "text/plain",
+			},
+			body
+		});
+	})
+	extraContainer.appendChild(checkButton);
 </script>
 
 {% endblock %}
\ No newline at end of file
diff --git a/templates/stack/new-form.html b/templates/stack/new-form.html
index 83cb918..a282d1a 100644
--- a/templates/stack/new-form.html
+++ b/templates/stack/new-form.html
@@ -8,11 +8,11 @@
 		<h1>New stack</h1>
 	</header>
 	<section class="editor">
-		<form method="POST" action="./edit" id="editor-form">
+		<form method="POST" id="editor-form">
 			<div class="row">
-				<input style="flex:1" name="name" type="text" placeholder="Stack name" />
+				<input style="flex:1" name="name" type="text" placeholder="Stack name" required />
 			</div>
-			<textarea name="source" id="editor">{}</textarea>
+			<textarea name="source" id="editor" required>{}</textarea>
 			<div class="row">
 				<button type="submit">Create & Deploy</button>
 			</div>
@@ -32,7 +32,7 @@
 <script type="module">
 	import Editor from "/static/js/ace.mjs";
 
-	new Editor("editor");
+	const editor = new Editor("editor");
 </script>
 
 {% endblock %}
\ No newline at end of file