diff --git a/.zed/settings.json b/.zed/settings.json
new file mode 100644
index 0000000..11c3cc2
--- /dev/null
+++ b/.zed/settings.json
@@ -0,0 +1,12 @@
+{
+  "languages": {
+    "XML": {
+      "prettier": {
+        "allowed": true,
+        "plugins": ["@prettier/plugin-xml"]
+      },
+      "format_on_save": "off",
+      "formatter": "prettier"
+    }
+  }
+}
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..a09574e
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,329 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
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+ "unicode-segmentation",
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+
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+ "equivalent",
+ "hashbrown",
+ "serde",
+]
+
+[[package]]
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+[[package]]
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+
+[[package]]
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+
+[[package]]
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+ "unicode-ident",
+]
+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1885c039570dc00dcb4ff087a89e185fd56bae234ddc7f056a945bf36467248d"
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+ "proc-macro2",
+]
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+[[package]]
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+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "56e6fa9c48d24d85fb3de5ad847117517440f6beceb7798af16b4a87d616b8d0"
+
+[[package]]
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+checksum = "5f0e2c6ed6606019b4e29e69dbaba95b11854410e5347d525002456dbbb786b6"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
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+checksum = "5b0276cf7f2c73365f7157c8123c21cd9a50fbbd844757af28ca1f5925fc2a00"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "serde_json"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "30b9eff21ebe718216c6ec64e1d9ac57087aad11efc64e32002bce4a0d4c03d3"
+dependencies = [
+ "itoa",
+ "memchr",
+ "ryu",
+ "serde",
+]
+
+[[package]]
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+version = "1.15.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "67b1b7a3b5fe4f1376887184045fcf45c69e92af734b7aaddc05fb777b6fbd03"
+
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+checksum = "c3e17e880bafaeb362a7b751ec46bdc5b61445a188f80e0606e68167cd540fa3"
+dependencies = [
+ "smallvec",
+]
+
+[[package]]
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+checksum = "17b6f705963418cdb9927482fa304bc562ece2fdd4f616084c50b7023b435a40"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a5f39404a5da50712a4c1eecf25e90dd62b613502b7e925fd4e4d19b5c96512"
+
+[[package]]
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+checksum = "f6ccf251212114b54433ec949fd6a7841275f9ada20dddd2f29e9ceea4501493"
+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+
+[[package]]
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+version = "0.201.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9c7d2731df60006819b013f64ccc2019691deccf6e11a1804bc850cd6748f1a"
+dependencies = [
+ "leb128",
+]
+
+[[package]]
+name = "wasm-metadata"
+version = "0.201.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fd83062c17b9f4985d438603cde0a5e8c5c8198201a6937f778b607924c7da2"
+dependencies = [
+ "anyhow",
+ "indexmap",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "spdx",
+ "wasm-encoder",
+ "wasmparser",
+]
+
+[[package]]
+name = "wasmparser"
+version = "0.201.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "84e5df6dba6c0d7fafc63a450f1738451ed7a0b52295d83e868218fa286bf708"
+dependencies = [
+ "bitflags",
+ "indexmap",
+ "semver",
+]
+
+[[package]]
+name = "wit-bindgen"
+version = "0.22.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "288f992ea30e6b5c531b52cdd5f3be81c148554b09ea416f058d16556ba92c27"
+dependencies = [
+ "bitflags",
+ "wit-bindgen-rt",
+ "wit-bindgen-rust-macro",
+]
+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e85e72719ffbccf279359ad071497e47eb0675fe22106dea4ed2d8a7fcb60ba4"
+dependencies = [
+ "anyhow",
+ "wit-parser",
+]
+
+[[package]]
+name = "wit-bindgen-rt"
+version = "0.22.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fcb8738270f32a2d6739973cbbb7c1b6dd8959ce515578a6e19165853272ee64"
+
+[[package]]
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+dependencies = [
+ "anyhow",
+ "heck",
+ "indexmap",
+ "wasm-metadata",
+ "wit-bindgen-core",
+ "wit-component",
+]
+
+[[package]]
+name = "wit-bindgen-rust-macro"
+version = "0.22.0"
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+checksum = "d376d3ae5850526dfd00d937faea0d81a06fa18f7ac1e26f386d760f241a8f4b"
+dependencies = [
+ "anyhow",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wit-bindgen-core",
+ "wit-bindgen-rust",
+]
+
+[[package]]
+name = "wit-component"
+version = "0.201.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "421c0c848a0660a8c22e2fd217929a0191f14476b68962afd2af89fd22e39825"
+dependencies = [
+ "anyhow",
+ "bitflags",
+ "indexmap",
+ "log",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "wasm-encoder",
+ "wasm-metadata",
+ "wasmparser",
+ "wit-parser",
+]
+
+[[package]]
+name = "wit-parser"
+version = "0.201.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "196d3ecfc4b759a8573bf86a9b3f8996b304b3732e4c7de81655f875f6efdca6"
+dependencies = [
+ "anyhow",
+ "id-arena",
+ "indexmap",
+ "log",
+ "semver",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "unicode-xid",
+ "wasmparser",
+]
+
+[[package]]
+name = "xml"
+version = "0.1.0"
+dependencies = [
+ "zed_extension_api",
+]
+
+[[package]]
+name = "zed_extension_api"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "594fd10dd0f2f853eb243e2425e7c95938cef49adb81d9602921d002c5e6d9d9"
+dependencies = [
+ "serde",
+ "serde_json",
+ "wit-bindgen",
+]
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..5238e58
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "xml"
+version = "0.1.0"
+edition = "2021"
+publish = false
+license = "MIT"
+
+[lib]
+path = "src/xml.rs"
+crate-type = ["cdylib"]
+
+[dependencies]
+zed_extension_api = "0.1.0"
diff --git a/README.md b/README.md
index 9ec7e3b..88fdb44 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,55 @@
 
 XML syntax highlighting for [Zed](https://github.com/zed-industries/zed).
 
+See the official [Zed XML Language Documentation](https://zed.dev/docs/languages/xml).
+
 ## Tree-Sitter
 
 - https://github.com/tree-sitter-grammars/tree-sitter-xml
+
+## Language Server
+
+This extension uses the [eclipse-lemminx/lemminx](https://github.com/eclipse-lemminx/lemminx) language server.  If a `lemminx` binary is found in your PATH that will be used, otherwise the extension will automatically download pre-built `lemminx` binaries for your platform from [redhat-developer/vscode-xml/releases](https://github.com/redhat-developer/vscode-xml/releases).
+
+## Formatter
+
+### Prettier
+
+Use [prettier](https://prettier.io/) with [prettier/plugin-xml](https://github.com/prettier/plugin-xml) to format:
+
+```json
+  "languages": {
+    "XML": {
+      "prettier": {
+        "allowed": true,
+        "plugins": ["@prettier/plugin-xml"]
+      },
+      "formatter": "prettier",
+    }
+  }
+```
+
+### Language Server
+
+Use `lemminx` language server to format documents:
+
+```json
+  "languages": {
+    "XML": {
+      "format_on_save": "on",
+      "formatter": "language_server"
+    }
+  }
+```
+
+### Manual formatting
+
+If you prefer, you can manually use `editor::FormatDocument` (`ctrl-shift-i` on Linux, `cmd-shift-i` on macOS) and disable automatic "Format on Save" with:
+
+```json
+  "languages": {
+    "XML": {
+      "format_on_save": "off"
+    }
+  }
+```
diff --git a/extension.toml b/extension.toml
index 96c0cf6..0e572b9 100644
--- a/extension.toml
+++ b/extension.toml
@@ -1,12 +1,19 @@
 id = "xml"
 name = "XML"
 description = "XML syntax support."
-version = "0.0.8"
+version = "0.1.0"
 schema_version = 1
-authors = ["sweetppro"]
+authors = ["sweetppro", "notpeter"]
 repository = "https://github.com/sweetppro/zed-xml"
 
 [grammars.xml]
 repository = "https://github.com/tree-sitter-grammars/tree-sitter-xml"
 commit = "4b64dd3a03ec002258d6268d712fd93716d6ab57"
 path = "xml"
+
+# Upstream: https://github.com/eclipse-lemminx/lemminx
+# Binaries: https://github.com/redhat-developer/vscode-xml
+[language_servers.lemminx]
+name = "lemminx"
+language = "XML"
+language_ids = { XML = "xml" }
diff --git a/src/xml.rs b/src/xml.rs
new file mode 100644
index 0000000..85cee00
--- /dev/null
+++ b/src/xml.rs
@@ -0,0 +1,117 @@
+use std::fs;
+use zed::LanguageServerId;
+use zed_extension_api::{self as zed, Result};
+
+struct XmlExtension {
+    cached_binary_path: Option<String>,
+}
+
+static LS_NAME: &str = "lemminx";
+
+impl XmlExtension {
+    fn language_server_binary_path(
+        &mut self,
+        language_server_id: &LanguageServerId,
+        worktree: &zed::Worktree,
+    ) -> Result<String> {
+        if let Some(path) = worktree.which(LS_NAME) {
+            return Ok(path);
+        }
+
+        if let Some(path) = &self.cached_binary_path {
+            if fs::metadata(path).map_or(false, |stat| stat.is_file()) {
+                return Ok(path.clone());
+            }
+        }
+
+        zed::set_language_server_installation_status(
+            language_server_id,
+            &zed::LanguageServerInstallationStatus::CheckingForUpdate,
+        );
+        let release = zed::latest_github_release(
+            "redhat-developer/vscode-xml",
+            zed::GithubReleaseOptions {
+                require_assets: true,
+                pre_release: false,
+            },
+        )?;
+
+        let (platform, arch) = zed::current_platform();
+
+        // See: https://github.com/redhat-developer/vscode-xml/releases
+        let artifact = match (platform, arch) {
+            (zed::Os::Mac, zed::Architecture::Aarch64) => "osx-aarch_64",
+            (zed::Os::Mac, zed::Architecture::X8664) => "osx-x86_64",
+            (zed::Os::Linux, zed::Architecture::X8664) => "linux",
+            (zed::Os::Linux, zed::Architecture::Aarch64) => {
+                return Err("unsupported platform: Linux aarch64.\nSee https://github.com/redhat-developer/vscode-xml/issues/930".into())
+            }
+            // TODO: When Windows aarch64 builds are available use those
+            (zed::Os::Windows, _) => "win32",
+            (_, zed::Architecture::X86) => return Err("unsupported architecture: 32bit x86".into()),
+        };
+        let binary_name = format!("{}-{}", LS_NAME, artifact);
+        let asset_name = format!("{}.zip", binary_name);
+
+        let asset = release
+            .assets
+            .iter()
+            .find(|asset| asset.name == asset_name)
+            .ok_or_else(|| format!("no asset found matching {:?}", asset_name))?;
+
+        let version_dir = format!("{}-{}", LS_NAME, release.version);
+        let extension = match platform {
+            zed::Os::Windows => ".exe",
+            _ => "",
+        };
+        let binary_path = format!("{}/{}{}", version_dir, binary_name, extension);
+
+        if !fs::metadata(&binary_path).map_or(false, |stat| stat.is_file()) {
+            zed::set_language_server_installation_status(
+                language_server_id,
+                &zed::LanguageServerInstallationStatus::Downloading,
+            );
+
+            zed::download_file(
+                &asset.download_url,
+                &version_dir,
+                zed::DownloadedFileType::Zip,
+            )
+            .map_err(|e| format!("failed to download file: {e}"))?;
+
+            let entries =
+                fs::read_dir(".").map_err(|e| format!("failed to list working directory {e}"))?;
+            for entry in entries {
+                let entry = entry.map_err(|e| format!("failed to load directory entry {e}"))?;
+                if entry.file_name().to_str() != Some(&version_dir) {
+                    fs::remove_dir_all(entry.path()).ok();
+                }
+            }
+        }
+
+        self.cached_binary_path = Some(binary_path.clone());
+        Ok(binary_path)
+    }
+}
+
+impl zed::Extension for XmlExtension {
+    fn new() -> Self {
+        Self {
+            cached_binary_path: None,
+        }
+    }
+
+    fn language_server_command(
+        &mut self,
+        language_server_id: &LanguageServerId,
+        worktree: &zed::Worktree,
+    ) -> Result<zed::Command> {
+        Ok(zed::Command {
+            command: self.language_server_binary_path(language_server_id, worktree)?,
+            args: Default::default(),
+            env: Default::default(),
+        })
+    }
+}
+
+zed::register_extension!(XmlExtension);